CN116136194A

CN116136194A - Engine compression ratio control method, device and storage medium

Info

Publication number: CN116136194A
Application number: CN202111360099.2A
Authority: CN
Inventors: 罗海鹏; 李林洁; 郭旭阳
Original assignee: Guangzhou Automobile Group Co Ltd
Current assignee: Guangzhou Automobile Group Co Ltd
Priority date: 2021-11-17
Filing date: 2021-11-17
Publication date: 2023-05-19

Abstract

The invention discloses an engine compression ratio control method, a device and a storage medium, wherein the method comprises the following steps: determining an actual compression ratio of the engine and determining a desired compression ratio of the engine; determining a compression ratio evaluation parameter value of the engine according to the expected compression ratio and the actual compression ratio of the engine; determining whether compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value; if the compression ratio of the engine is required to be adjusted, the compression ratio of the engine is subjected to closed-loop adjustment, so that the actual compression ratio of the engine meets the requirement; in the invention, the expected compression ratio and the actual compression ratio are compared and analyzed, and the compression ratio evaluation parameter value is established to correct the compression ratio of the engine in time, so that the responsiveness of compression ratio control is improved, the accurate control of the compression ratio of the engine is realized, the compression ratio of the engine can reach the optimal state, and the engine can work efficiently.

Description

Engine compression ratio control method, device and storage medium

Technical Field

The present invention relates to the field of vehicle control technologies, and in particular, to a method and an apparatus for controlling an engine compression ratio, and a storage medium.

Background

With the increasing demands of users on the dynamics and economy of automobiles, the performance demands of engines, one of the important parts of automobiles, are also increasing. Currently, the application of a variable compression ratio (Variable Compress Ratio, VCR) engine is very wide, and the VCR engine can achieve the purposes of reducing oil consumption and improving emission by controlling the actual compression ratio, thereby improving the dynamic property and economy of the VCR engine.

In the prior art, for compression ratio control of a variable compression ratio engine, the operation condition of a VCR engine is generally divided into regions, and different regions have different operation compression ratios, and during the actual operation of the VCR engine, when the engine condition is operated in a specific region, the compression ratio is maintained at a specific value, for example: the high compression ratio is used when the CR engine operating condition is operating in the low load region and the low compression ratio is used when the CR engine operating condition is operating in the high load region. However, the compression ratio of the VCR engine is not controlled accurately, so that the compression ratio of the VCR engine cannot reach the optimal state, and the working efficiency of the VCR engine is low.

Disclosure of Invention

The invention provides an engine compression ratio control method, an engine compression ratio control device and a storage medium, which are used for solving the problem that in the prior art, the compression ratio of a variable compression ratio engine is controlled inaccurately, so that the working efficiency of the engine is low.

Provided is an engine compression ratio control method including:

determining an actual compression ratio of the engine and determining a desired compression ratio of the engine;

determining a compression ratio evaluation parameter value of the engine according to the expected compression ratio and the actual compression ratio of the engine;

determining whether compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value;

if the compression ratio of the engine needs to be adjusted, the compression ratio of the engine is adjusted in a closed loop mode, so that the actual compression ratio of the engine meets the requirement.

Further, in the process of performing closed-loop adjustment on the compression ratio of the engine, the method further comprises:

monitoring the change rate of the actual compression ratio to determine whether the change rate is within a preset rate range;

if the change rate is within the preset rate range, controlling the engine to normally operate;

and if the actual compression ratio is not in the preset speed range, limiting the rotating speed and the torque of the engine until the engine stops running.

Further, after determining the actual compression ratio of the engine, the method further comprises:

determining whether the actual compression ratio is within a preset compression ratio range;

if the actual compression ratio is within the preset compression ratio range, controlling the engine to normally operate;

And if the actual compression ratio is not in the preset compression ratio range, limiting the rotating speed and the torque of the engine until the engine stops running.

Further, determining an actual compression ratio of the engine and determining a desired compression ratio of the engine includes:

determining an actual rotation speed and an actual load of an engine, and determining a control shaft phase of a compression ratio control shaft;

determining the actual compression ratio of the engine according to first preset data and the control shaft phase, wherein the first preset data is the compression ratio of the engine at different control shaft phase values in the actual working process;

and determining the expected compression ratio of the engine according to second preset data, the actual rotating speed and the actual load, wherein the second preset data is the optimal compression ratio of the engine under different working conditions and calibrated in advance.

Further, determining whether compression ratio adjustment of the engine is required based on the compression ratio evaluation parameter value includes:

when the compression ratio evaluation parameter value is a positive number, determining whether the compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value and the first fluctuation threshold value;

when the compression ratio evaluation parameter value is negative, determining whether the compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value and the magnitude of the second fluctuation threshold value.

Further, the compression ratio of the engine is controlled by a compression ratio hydraulic system including a hydraulic solenoid valve, which performs closed-loop adjustment of the compression ratio of the engine so that the actual compression ratio of the engine satisfies the requirement, including:

determining a target duty ratio of the hydraulic solenoid valve according to third preset data and an expected compression ratio, wherein the third preset data comprises different engine compression ratios and the corresponding hydraulic solenoid valve duty ratio of the engine compression ratios;

controlling a hydraulic solenoid valve according to a target duty ratio to perform PID control on the compression ratio of the engine;

in the PID control process, determining whether a compression ratio difference between a desired compression ratio and an actual compression ratio meets a preset condition;

and if the compression ratio difference value meets the preset condition, determining that the actual compression ratio of the engine meets the requirement.

Further, before determining the actual compression ratio of the engine, the method further comprises:

determining whether the compression ratio hydraulic system fails;

if the compression ratio hydraulic system does not have faults, acquiring the actual compression ratio of the engine;

if the compression ratio hydraulic system fails, determining whether the compression ratio hydraulic system has a physical locking function;

If the compression ratio hydraulic system has a physical locking function, when a user has a vehicle demand, the compression ratio of the engine is controlled according to fourth preset data, and the compression ratio of the engine under different working conditions in a fourth preset data fault mode is controlled.

Provided is an engine compression ratio control apparatus including:

a first determination module for determining an actual compression ratio of the engine and determining a desired compression ratio of the engine;

a second determining module for determining a compression ratio evaluation parameter value of the engine according to the expected compression ratio and the actual compression ratio of the engine;

the third determining module is used for determining whether compression ratio adjustment is needed to be carried out on the engine according to the compression ratio evaluation parameter value;

and the adjusting module is used for carrying out closed-loop adjustment on the compression ratio of the engine if the compression ratio of the engine is required to be adjusted, so that the actual compression ratio of the engine meets the requirement.

There is provided an engine compression ratio control apparatus comprising a memory, a processor and a computer program stored in the memory and operable on the processor, the processor executing the computer program to perform the steps of the engine compression ratio control method described above.

There is provided a readable storage medium storing a computer program which, when executed by a processor, implements the steps of the engine compression ratio control method described above.

In one scheme provided by the method, the device and the storage medium for controlling the engine compression ratio, the actual compression ratio of the engine is determined, the expected compression ratio of the engine is determined, then the compression ratio evaluation parameter value of the engine is determined according to the expected compression ratio and the actual compression ratio of the engine, whether the engine needs to be subjected to compression ratio adjustment or not is determined according to the compression ratio evaluation parameter value, and if the engine needs to be subjected to compression ratio adjustment, the compression ratio of the engine is subjected to closed-loop adjustment so that the actual compression ratio of the engine meets the requirement; in the invention, the expected compression ratio and the actual compression ratio are compared and analyzed, and the compression ratio evaluation parameter value is established to correct the compression ratio of the engine in time, so that the responsiveness of compression ratio control is improved, the accurate control of the compression ratio of the engine is realized, the compression ratio of the engine can reach the optimal state, and the engine can work efficiently.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments of the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort to a person skilled in the art.

FIG. 1 is a schematic diagram of an engine compression ratio control system according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method for controlling the compression ratio of an engine according to an embodiment of the invention;

FIG. 3 is another flow chart of a method of controlling engine compression ratio in accordance with an embodiment of the present invention;

FIG. 4 is a flowchart illustrating an implementation of step S40 in FIG. 2;

FIG. 5 is a schematic view showing a structure of an engine compression ratio control apparatus according to an embodiment of the present invention;

fig. 6 is another structural diagram of an engine compression ratio control apparatus in an embodiment of the invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The engine compression ratio control method provided by the embodiment of the invention can be applied to an engine compression ratio control system shown in fig. 1, wherein the engine compression ratio control system comprises a compression ratio hydraulic system 1 and an engine compression ratio control device 2, and the compression ratio hydraulic system 1 is communicated with the engine compression ratio control device 2 through a vehicle bus.

In the present embodiment, the compression ratio hydraulic system 1 includes an engine 11, a hydraulic solenoid valve 12, a hydraulic limiter 13, a compression ratio control shaft 14, and a multiple link structure 15. The engine 11 is a variable compression ratio engine; the hydraulic solenoid valve 13 is used to adjust and maintain the compression ratio of the engine 11; the hydraulic solenoid valve 12 is used for distributing the flow of the hydraulic limiter 13; the compression ratio control shaft 14 is an execution device for adjusting the compression ratio of the engine 11 in cooperation with the hydraulic limiter 13, and the compression ratio control shaft 14 adjusts the compression ratio of the engine 11 through the multi-link structure 15; the multiple connecting rod structure 15 is a part of the engine 11, and is composed of multiple connecting rods and a crankshaft. The engine compression ratio control device 2 may be an electronic control unit (Electronic Control Unit, ECU) on the engine 11, and in other embodiments, the engine compression ratio control device 2 may also be other control devices on the vehicle, which will not be described here.

After the vehicle is powered on, the ECU determines the actual compression ratio of the engine and determines the desired compression ratio of the engine; then, according to the expected compression ratio and the actual compression ratio of the engine, determining a compression ratio evaluation parameter value of the engine; determining whether the compression ratio of the engine is required to be adjusted according to the compression ratio evaluation parameter value, and if the compression ratio of the engine is required to be adjusted, performing closed-loop adjustment on the compression ratio of the engine so that the actual compression ratio of the engine meets the requirement; by comparing and analyzing the expected compression ratio and the actual compression ratio, a compression ratio evaluation parameter value is established to correct the compression ratio of the engine in time, the responsiveness of compression ratio control is improved, the accurate control of the compression ratio of the engine is realized, the compression ratio of the engine can reach the optimal state, and therefore the engine can work stably and efficiently, and the power performance and the economic performance of the engine are improved.

In this embodiment, the engine compression ratio control system includes a compression ratio hydraulic system and an engine compression ratio control device, the compression ratio hydraulic system includes an engine, a hydraulic solenoid valve, a hydraulic limiter, a compression ratio control shaft and a multi-link structure, which are all only illustrated by way of example, and in other embodiments, the engine compression ratio control system and the compression ratio hydraulic system may also include other structures, such as a phase sensor, which will not be described herein.

In one embodiment, as shown in fig. 2, an engine compression ratio control method is provided, and the method is applied to the engine compression ratio control apparatus in fig. 1, and includes the following steps:

s10: an actual compression ratio of the engine is determined, and a desired compression ratio of the engine is determined.

After the vehicle is powered on, an engine compression ratio control device (ECU) needs to monitor the actual compression ratio of the engine in the compression ratio hydraulic system in real time to determine the actual compression ratio of the engine, and at the same time, also needs to determine the desired compression ratio of the engine to perform adjustment control on the compression ratio of the engine according to the relationship between the actual compression ratio and the desired compression ratio of the engine.

In the compression ratio hydraulic system, the phase of the compression ratio control shaft is adjusted to change the phase of the compression ratio control shaft and the phase of a multi-link structure of the engine, so that the compression ratio of the engine is adjusted, the phase of the compression ratio control shaft (the phase of the control shaft) and the compression ratio of the engine are in one-to-one correspondence, the phase of the multi-link structure and the compression ratio of the engine are also in one-to-one correspondence, and the actual compression ratio of the engine can be determined by controlling the phase of the shaft or the phase of the multi-link structure. Therefore, in this embodiment, a phase sensor may be installed at the compression ratio control shaft or the multi-link structure, and when the vehicle is powered on, the ECU is powered on and starts to collect the control shaft phase or the phase of the multi-link structure to determine the actual compression ratio of the engine.

Wherein the expected compression ratio of the engine is the optimal compression ratio of the engine under the current working condition. The desired compression ratio of the engine is determined by the current operating conditions of the engine.

S20: a compression ratio evaluation parameter value of the engine is determined based on a desired compression ratio and an actual compression ratio of the engine.

After determining the actual compression ratio of the engine and determining the desired compression ratio of the engine, it is necessary to determine the compression ratio evaluation parameter value of the engine based on the desired compression ratio and the actual compression ratio of the engine.

In this embodiment, in order to facilitate calculation to reduce the calculation amount of the ECU and increase the compression ratio response speed, the compression ratio evaluation parameter value of the engine may be a compression ratio difference between the desired compression ratio and the actual compression ratio of the engine, where the calculation formula is as follows:

Δε＝ε _t -ε _c ；

wherein Deltaepsilon is the compression ratio evaluation parameter value of the engine _t Epsilon for the desired compression ratio of the engine _c Is the actual compression ratio of the engine.

In the present embodiment, the compression ratio evaluation parameter value of the engine, which is the compression ratio difference between the desired compression ratio and the actual compression ratio of the engine, is merely an exemplary illustration, and in other embodiments, the compression ratio evaluation parameter value of the engine may be determined in other manners. For example, an average value of the compression ratio difference between the desired compression ratio and the actual compression ratio of the engine over a preset period is taken as the compression ratio evaluation parameter value of the engine to improve the accuracy of the compression ratio evaluation parameter value, thereby reducing frequent adjustment of the compression ratio of the engine. Or after the vehicle is electrified, the compression ratio difference between the expected compression ratio and the actual compression ratio of the engine is integrated, and the integrated result is used as a compression ratio evaluation parameter value, so that the accuracy of the compression ratio evaluation parameter value is further improved.

The actual compression ratio of the engine is dynamically changed in real time, and the expected compression ratio of the engine is changed along with the change of the real-time working condition of the engine, so that the compression ratio evaluation parameter value of the engine is also data of the real-time dynamic change.

S30: and determining whether the compression ratio of the engine is required to be adjusted according to the compression ratio evaluation parameter value.

After the compression ratio evaluation parameter value of the engine is determined according to the desired compression ratio and the actual compression ratio of the engine, the actual compression ratio is judged according to the magnitude of the compression ratio evaluation parameter value to determine whether the compression ratio adjustment of the engine is required.

After determining whether the compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value, if the compression ratio adjustment of the engine is not required, controlling the compression ratio hydraulic system to enter a normal mode to respond to the normal power demand of the vehicle.

S40: if the compression ratio of the engine needs to be adjusted, the compression ratio of the engine is adjusted in a closed loop mode, so that the actual compression ratio of the engine meets the requirement.

After determining whether the compression ratio of the engine needs to be adjusted according to the compression ratio evaluation parameter value, if the compression ratio of the engine needs to be adjusted, the difference between the actual compression of the current engine and the expected compression ratio is too large, and the actual compression of the current engine does not meet the requirement.

The steps S10-S30 are repeated, that is, in the adjusting process, the desired compression ratio and the actual compression ratio of the engine are required to be obtained in real time, then the real-time compression ratio evaluation parameter value is determined, then the circulation judgment is performed according to the real-time compression ratio evaluation parameter value to determine whether the compression ratio of the engine needs to be adjusted, if the compression ratio of the engine needs to be adjusted, the position of the hydraulic limiter is changed by changing the duty ratio of the hydraulic solenoid valve, so that the phase of the compression ratio control shaft matched with the hydraulic limiter is changed, and then the phase of the multi-link structure is changed, so that the compression ratio adjustment of the engine is realized until the adjusted actual compression ratio meets the requirement.

In the embodiment, the optimal compression ratio (expected compression ratio) of the engine under the current working condition is determined, then the compression ratio is compared with the actual compression ratio of the engine which is measured in real time, a compression ratio evaluation parameter value is established to correct the compression ratio of the engine in time, the change of the actual compression ratio is monitored according to the iterative analysis of the compression ratio evaluation parameter value, the actual compression ratio is subjected to closed-loop control and adjustment based on the hydraulic electromagnetic valve, the responsiveness of the compression ratio control is improved, and the accurate and efficient control of the compression ratio of the engine is realized.

In the present embodiment, the desired compression ratio of the engine is determined by the actual compression ratio of the engine; then, according to the expected compression ratio and the actual compression ratio of the engine, determining a compression ratio evaluation parameter value of the engine; determining whether the compression ratio of the engine is required to be adjusted according to the compression ratio evaluation parameter value, and if the compression ratio of the engine is required to be adjusted, performing closed-loop adjustment on the compression ratio of the engine so that the actual compression ratio of the engine meets the requirement; by comparing and analyzing the expected compression ratio and the actual compression ratio, a compression ratio evaluation parameter value is established to correct the compression ratio of the engine in time, the responsiveness of compression ratio control is improved, the accurate control of the compression ratio of the engine is realized, the compression ratio of the engine can reach the optimal state, and therefore the engine can work stably and efficiently, and the power performance and the economic performance of the engine are improved.

In one embodiment, in step S10, the actual compression ratio of the engine is determined, and the desired compression ratio of the engine is determined, specifically including the steps of:

s11: an actual rotational speed and an actual load of the engine are determined, and a control shaft phase of the compression ratio control shaft is determined.

After the vehicle is powered up, the ECU needs to determine the actual rotational speed and the actual load of the engine and determine the control shaft phase of the compression ratio control shaft in the compression ratio hydraulic system.

In this embodiment, the ECU includes a function of monitoring the phase of the compression ratio control shaft, the actual rotational speed of the engine, and the actual load, and the ECU can monitor and collect the phase of the control shaft of the compression ratio control shaft, the actual rotational speed of the engine, and the actual load in real time after the ECU is powered on.

S12: and determining the actual compression ratio of the engine according to the first preset data and the control shaft phase.

After the vehicle is powered on, the ECU also needs to acquire first preset data. The first preset data are compression ratios of the engine at different control shaft phase values in the actual working process. The first preset data are data calibrated according to the design structure of the compression ratio hydraulic system. When the compression ratio hydraulic system is designed, the actual compression ratio of the engine changes along with the change of the phase of the control shaft, and the phase value of the control shaft corresponds to the compression ratio of the engine one by one. In order to ensure the accuracy of the data, after the engine is assembled, a compression ratio test can be performed on the engine to obtain the compression ratio of the engine at different control shaft phase values, so that the pre-calibrated first preset data are calibrated. The first preset data comprise compression ratios of the engine at different control shaft phase values, and the control shaft phase values correspond to the compression ratios of the engine one by one.

After determining a control shaft phase of a compression ratio control shaft in a compression ratio hydraulic system, an actual compression ratio of the engine is determined based on the first preset data and the control shaft phase.

After the control shaft phase of the compression ratio control shaft is determined, the compression ratio of the engine corresponding to the control shaft phase is inquired in the first preset data, and the compression ratio is used as the compression ratio of the engine, so that the method is quick, simple and high in accuracy. In this embodiment, the compression ratio of the engine can be actively controlled by the compression ratio control shaft, so that the compression ratio of the engine is determined by using the control shaft phase, and the accuracy is higher.

S13: and determining the expected compression ratio of the engine according to the second preset data, the actual rotating speed and the actual load.

After the vehicle is powered up, the ECU also needs to acquire second preset data. The second preset data are calibrated in advance, and the engine is expected to have the optimal compression ratio under different working conditions (different rotating speeds and different loads). The second preset data are obtained by testing compression ratios of the engine under different working conditions, and data accuracy is ensured. The engine has different optimal compression ratios under different rotation speeds and loads, so that the expected compression ratio of the engine can be determined according to the second preset data, the actual rotation speed and the actual load when the actual rotation speed and the actual load of the engine are determined. And searching the optimal compression ratio corresponding to the actual rotation speed and the actual load at the same time in the second preset data, and taking the optimal compression ratio as the expected compression ratio of the engine.

In other embodiments, after the first preset data and the second preset data are obtained, the first preset data and the second preset data may be made into maps, respectively, a first Map (Map _θ ) Second Map (Map _ε ) Then Map is made _θ 、 Map _ε Built-in the memory of the ECU. In obtaining the actual rotation speed and the actual rotation speed of the engineAfter the inter-load is determined and the control shaft phase of the compression ratio control shaft is determined, the control shaft phase is directly controlled at Map _θ Searching the actual compression ratio, and directly locating the actual compression ratio on Map according to the actual rotation speed and the actual load _ε The expected compression ratio is searched, the data processing capacity is reduced, the data determination speed is improved, and the subsequent compression ratio adjustment response speed is improved.

In this embodiment, by determining the actual rotation speed and the actual load of the engine and determining the control shaft phase of the compression ratio control shaft in the compression ratio hydraulic system, then determining the actual compression ratio of the engine according to the first preset data and the control shaft phase, and simultaneously determining the desired compression ratio of the engine according to the second preset data, the actual rotation speed and the actual load, the specific process of determining the actual compression ratio of the engine in the compression ratio hydraulic system and determining the desired compression ratio of the engine is clarified, the data processing is fast, and the accuracy of the data is ensured.

In one embodiment, as shown in fig. 3, after step S10, i.e. after determining the actual compression ratio of the engine, the method further specifically includes the steps of:

s101: it is determined whether an actual compression ratio of the engine is within a preset compression ratio range.

After the actual compression ratio of the engine in the compression ratio hydraulic system is determined, the actual compression ratio of the engine needs to be monitored, so that when the actual compression ratio of the engine exceeds a safe compression ratio range, the engine is limited to a certain extent, and the driving safety is ensured.

That is, after determining the actual compression ratio of the engine in the compression ratio hydraulic system, it is necessary to determine whether the actual compression ratio of the engine is within a preset compression ratio range. The preset compression ratio range is a pre-calibrated allowed engine compression ratio range, the maximum value of the preset compression ratio range is an allowed engine compression ratio upper limit value, and the minimum value of the preset compression ratio range is an allowed engine compression ratio lower limit value.

To ensure the running safety of the vehicle, it is necessary to control the actual compression ratio of the engine to be within a preset compression ratio range, that is, to determine whether the actual compression ratio is within the preset compression ratio range by:

Determining whether an actual compression ratio of an engine is greater than an upper limit epsilon of the compression ratio of the engine _cmax And determining whether the actual compression ratio of the engine is less than the lower limit value epsilon of the compression ratio of the engine _cmin The method comprises the steps of carrying out a first treatment on the surface of the If the actual compression ratio of the engine is smaller than or equal to the upper limit value of the compression ratio of the engine and the actual compression ratio of the engine is larger than or equal to the lower limit value of the compression ratio of the engine, the actual compression ratio of the engine is determined to be in a preset compression ratio range, the actual compression ratio of the engine is controlled normally, and the engine is controlled according to a normal control logic, so that the engine runs normally. If the actual compression ratio of the engine is larger than the upper limit value of the compression ratio of the engine or the actual compression ratio of the engine is smaller than the lower limit value of the compression ratio of the engine, the actual compression ratio of the engine is determined to be not in a preset compression ratio range, the actual compression ratio of the engine is abnormal, the compression ratio hydraulic system is likely to fail, and the engine is required to be limited to stop the engine and stop running of the vehicle in order to ensure running safety.

S101: and if the actual compression ratio is in the preset compression ratio range, controlling the engine to normally operate.

After determining whether the actual compression ratio of the engine is within the preset compression ratio range, if the actual compression ratio is within the preset compression ratio range, the actual compression ratio of the engine is normally controllable, and the engine is controlled according to the normal control logic to control the engine to normally operate.

S101: and if the actual compression ratio is not in the preset compression ratio range, limiting the rotating speed and the torque of the engine until the engine stops running.

After determining whether the actual compression ratio of the engine is within the preset compression ratio range, if the actual compression ratio is not within the preset compression ratio range, the actual compression ratio of the engine is abnormal, and the compression ratio hydraulic system may malfunction, so that the engine is prevented from being damaged, driving safety is ensured, and the rotation speed and torque of the engine need to be limited until the engine stops running, thereby enabling the vehicle to stop running safely. Meanwhile, the engine needs to be controlled to give an alarm so that a user can know the actual compression ratio in time to perform corresponding processing.

In this embodiment, after determining the actual compression ratio of the engine, by determining whether the actual compression ratio of the engine is within a preset compression ratio range, if the actual compression ratio is within the preset compression ratio range, the engine is controlled to operate normally; if the actual compression ratio is not in the preset compression ratio range, limiting the rotating speed and the torque of the engine until the engine stops running; the actual compression ratio of the engine is monitored in real time in the running process of the engine, so that the engine is timely subjected to speed and torque limiting when the actual compression ratio of the engine is abnormal, and the engine is stopped, so that the safety of the engine and the driving safety are ensured.

In one embodiment, step S30, i.e. determining whether the compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value, specifically includes the following steps:

s31: when the compression ratio evaluation parameter value is positive, determining whether the compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value and the magnitude of the first fluctuation threshold value.

In the present embodiment, the compression ratio evaluation parameter value of the engine is described as an example of the compression ratio difference between the desired compression ratio and the actual compression ratio of the engine, that is, Δε=ε _t -ε _c For example, for subsequent computation, the data throughput is reduced.

After determining the compression ratio evaluation parameter value of the engine, it is determined whether the compression ratio evaluation parameter value of the engine is greater than 0, that is, whether the desired compression ratio of the engine is greater than the actual compression ratio. If the compression ratio evaluation parameter value of the engine is larger than 0, the compression ratio evaluation parameter value is a positive number, and the expected compression ratio of the engine is larger than the actual compression ratio; if the compression ratio evaluation parameter value of the engine is smaller than 0, the compression ratio evaluation parameter value is negative, which means that the expected compression ratio of the engine is smaller than the actual compression ratio, and different judgment logics are executed according to different determination results.

When the compression ratio evaluation parameter value of the engine is positive (greater than 0), it is indicated that the desired compression ratio of the engine is greater than the actual compression ratio, and at this time, it is necessary to determine whether or not compression ratio adjustment of the engine is necessary, based on the magnitude of the compression ratio evaluation parameter value and the first fluctuation threshold value. The first fluctuation threshold value is a fluctuation lower limit threshold value of a pre-calibrated engine compression ratio. The first fluctuation threshold value is obtained according to the calibration of the engine compression ratio test result, and is the minimum difference between the allowable expected compression ratio and the actual compression ratio of the engine.

Determining whether compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value of the engine and the magnitude of the first fluctuation threshold value comprises the following steps: acquiring a first fluctuation threshold delta epsilon _llimit Determining whether the compression ratio evaluation parameter value is greater than a first fluctuation threshold; if the compression ratio evaluation parameter value is less than or equal to the first fluctuation threshold value, namely delta epsilon is less than or equal to delta epsilon _llimit The compression ratio evaluation parameter value delta epsilon meets the fluctuation requirement, and the compression ratio difference value between the expected compression ratio and the actual compression ratio of the engine is considered to be within the allowable deviation, so that the compression ratio adjustment of the engine is not needed, and the hydraulic electromagnetic valve does not need to be replaced; if the compression ratio evaluation parameter value is greater than the first fluctuation threshold, i.e., Δε > Δε _llimit If the compression ratio evaluation parameter Δε does not satisfy the fluctuation demand and the compression ratio difference between the desired compression ratio and the actual compression ratio of the engine is considered to be small, the compression ratio of the engine needs to be adjusted, that is, the hydraulic solenoid valve needs to be controlled to operate so as to increase the actual compression ratio of the engine.

S31: when the compression ratio evaluation parameter value is negative, determining whether the compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value and the magnitude of the second fluctuation threshold value.

When the compression ratio evaluation parameter value of the engine is negative (less than 0), it is indicated that the desired compression ratio of the engine is smaller than the actual compression ratio, and at this time, it is necessary to determine whether the compression ratio adjustment of the engine is necessary according to the magnitudes of the compression ratio evaluation parameter value and the second fluctuation threshold value. The second fluctuation threshold value is a fluctuation upper limit threshold value of the pre-calibrated engine compression ratio. The second fluctuation threshold value is obtained according to the calibration of the engine compression ratio test result and is the maximum difference between the allowable expected compression ratio and the actual compression ratio of the engine.

Determining whether compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value of the engine and the magnitude of the second fluctuation threshold value comprises the following steps: obtaining a second fluctuation threshold Deltaepsilon _ulimit Determining whether an absolute value of the compression ratio evaluation parameter value is greater than a first fluctuation threshold; if the absolute value of the compression ratio evaluation parameter value is less than or equal to the first fluctuation threshold value, i.e., |Deltaε|is less than or equal to Deltaε _ulimit The compression ratio evaluation parameter delta epsilon meets the fluctuation requirement, and the compression ratio difference value between the expected compression ratio and the actual compression ratio of the engine is considered to be within the allowable deviation, so that the compression ratio adjustment of the engine is not needed, and the hydraulic electromagnetic valve does not need to be replaced; if the absolute value of the compression ratio evaluation parameter value is greater than the second fluctuation threshold, i.e., |Deltaε| > Deltaε _ulimit If the compression ratio evaluation parameter Δε does not satisfy the fluctuation demand, it is considered that the difference between the desired compression ratio and the actual compression ratio of the engine is large, the compression ratio of the engine needs to be adjusted, that is, the hydraulic solenoid valve needs to be controlled to operate, so as to reduce the actual compression ratio of the engine.

In this embodiment, when the compression ratio evaluation parameter value is a positive number, whether the compression ratio adjustment of the engine is required is determined according to the compression ratio evaluation parameter value and the magnitude of the first fluctuation threshold; when the compression ratio evaluation parameter value is negative, determining whether the compression ratio adjustment is needed for the engine according to the compression ratio evaluation parameter value and the second fluctuation threshold value, determining whether the compression ratio adjustment is needed for the engine according to the compression ratio evaluation parameter value, judging whether the actual compression ratio of the engine needs to be adjusted according to the compression ratio evaluation parameter value, adopting different evaluation threshold values according to different compression ratio evaluation parameter values, and guaranteeing the accuracy of a determination result, thereby guaranteeing the accuracy of the follow-up compressor control for the engine.

In one embodiment, in step S40, the compression ratio of the engine is controlled by a compression ratio hydraulic system, which includes a hydraulic solenoid valve, that is, the compression ratio of the engine is closed-loop adjusted so that the actual compression ratio of the engine meets the requirement, and specifically includes the following steps:

s41: and determining a target duty ratio of the hydraulic solenoid valve according to the third preset data and the expected compression ratio.

After it is determined that the compression ratio adjustment of the engine is required based on the compression ratio evaluation parameter value, third preset data is required. The third preset data are data calibrated in advance according to the structure of the hydraulic system, the third preset data comprise different engine compression ratios and hydraulic solenoid valve duty ratios corresponding to the engine compression ratios, and the engine compression ratios and the hydraulic solenoid valve duty ratios correspond to each other one by one.

After the third preset data are acquired, the duty ratio of the hydraulic solenoid valve corresponding to the expected compression ratio of the current engine is searched in the third preset data and is used as the target duty ratio of the hydraulic solenoid valve.

The third preset data can be converted into a Map to obtain a third Map, then the third Map is built in the ECU, and after the compression ratio adjustment of the engine is determined to be needed, the target duty ratio of the hydraulic solenoid valve is directly determined at the third Map according to the current expected compression ratio, so that the data processing amount is reduced, and the acquisition speed of the target duty ratio of the hydraulic solenoid valve is improved.

S42: the hydraulic solenoid valve is controlled according to the target duty ratio to perform PID control on the compression ratio of the engine.

After the target duty ratio of the hydraulic solenoid valve is determined, the hydraulic solenoid valve is controlled according to the target duty ratio to perform PID control on the compression ratio of the engine. PID control, namely Proportional, integral and Differential control, is operated according to the input deviation value (namely the compression ratio difference between the expected compression ratio and the actual compression ratio) according to the functional relation of proportion, integral and Differential, and the operation result is used for controlling output, so that the PID control has higher data control precision.

The target duty ratio can be directly sent to the hydraulic electromagnetic valve, so that PID control on the compression ratio of the engine is realized through control of the hydraulic electromagnetic valve, and the actual compression ratio of the engine is quickly close to the expected compression ratio.

In an embodiment, after determining the target duty cycle of the hydraulic solenoid valve, the working duty cycle of the current hydraulic solenoid valve may also be obtained, and then duty cycle control information is generated according to the working duty cycle and the target duty cycle, where the duty cycle control information is composed of a plurality of duty cycles from the working duty cycle to the target duty cycle; and finally, controlling the hydraulic electromagnetic valve according to the duty ratio control information to perform PID control on the compression ratio of the engine, so that the actual compression ratio of the engine gradually approaches to the expected compression ratio, the fluctuation condition of the compression ratio of the engine is reduced, and the running stability of the engine is ensured.

For example, when the current duty cycle of the hydraulic solenoid valve is 10% and the target duty cycle is 20%, the duty cycle control information includes a plurality of duty cycles such as 12%, 14%, 16%, 18%, 20%, and the like, and after the duty cycle control information is obtained, the ECU sequentially transmits the duty cycles such as 12%, 14%, 16%, 18%, 20%, and the like to the hydraulic solenoid valve, so that the actual compression ratio of the engine gradually approaches the desired compression ratio after a plurality of changes, thereby achieving the compression ratio adjustment requirement.

In this embodiment, the duty cycle control information includes a plurality of duty cycles such as 12%, 14%, 16%, 18%, 20% and the like, and is merely illustrative, and in other embodiments, the duty cycle of the current hydraulic solenoid valve and the duty cycle target may be other values, and the duty cycle control information includes a plurality of duty cycles that may be other values, which are not described herein.

S43: in the PID control process, it is determined whether or not a compression ratio difference between a desired compression ratio and an actual compression ratio satisfies a preset condition.

In the process of PID control of the compression ratio of the engine, the actual rotation speed and the actual load of the engine are required to be obtained in real time, the control shaft phase of the compression ratio control shaft is required to be obtained in real time, the expected compression ratio of the current engine is determined according to the actual rotation speed and the actual load of the engine, the actual compression ratio of the engine is determined according to the control shaft phase, and then the compression ratio difference between the expected compression ratio and the actual compression ratio of the current engine is determined, whether a preset condition is met or not, namely whether the actual compression ratio of the engine is adjusted to be close to the expected compression ratio is determined. In this embodiment, if the compression ratio evaluation parameter value is the compression ratio difference between the desired compression ratio and the actual compression ratio of the engine is Δε, that is, if the compression ratio evaluation parameter value satisfies the preset condition in the PID control process, it may be determined.

Wherein determining whether the compression ratio difference Δε between the desired compression ratio and the actual compression ratio of the current engine meets a preset condition comprises:

a. when Δε is greater than 0, and determining whether Δε is greater than a first fluctuation threshold Δε _llimit The method comprises the steps of carrying out a first treatment on the surface of the If delta epsilon is less than or equal to the first fluctuation threshold delta epsilon _llimit I.e. Δε < 0 and Δε.ltoreq.Δε _llimit When the actual compression ratio of the engine is adjusted to be close to the expected compression ratio, the compression ratio difference between the expected compression ratio and the actual compression ratio of the engine meets a preset condition, and the hydraulic solenoid valve is maintained to work at the current duty ratio; if Δε is greater than the first threshold, i.e., Δε < 0 and Δε > Δε _llimit When the compression ratio difference between the expected compression ratio and the actual compression ratio of the engine does not meet the preset condition, the actual compression ratio of the engine is not regulated to be close to the expected compression ratio, and the duty ratio of the hydraulic solenoid valve needs to be continuously changed by taking the target duty ratio as a target until delta epsilon is less than or equal to delta epsilon _llimit 。

b. When Δε is less than 0, it is determined whether the absolute value of Δε is greater than a second fluctuation threshold Δε _ulimit The method comprises the steps of carrying out a first treatment on the surface of the If the absolute value of Δε is less than or equal to the second fluctuation threshold, i.e., Δε < 0 and |Δε| Δε _ulimit When the compression ratio difference between the expected compression ratio and the actual compression ratio of the engine meets a preset condition, the actual compression ratio of the engine is regulated to be close to the expected compression ratio, and the hydraulic solenoid valve is maintained to work at the current duty ratio at the moment; if the absolute value of delta epsilon is greater than that of the second The fluctuation threshold, i.e. Δε < 0 and |Δε| > Δε _ulimit When the difference between the expected compression ratio and the actual compression ratio of the engine does not meet the preset condition, the actual compression ratio of the engine is not regulated to be close to the expected compression ratio, and the duty ratio of the hydraulic solenoid valve needs to be continuously changed by taking the target duty ratio as a target until the absolute delta epsilon is less than or equal to the absolute delta epsilon _ulimit 。

The steps a and b define a specific process of determining whether the compression ratio difference value between the expected compression ratio and the actual compression ratio of the engine meets the preset condition, and execute different judgment strategies according to different compression ratio difference values, so that the accuracy of the judgment result is ensured, and the compression ratio of the engine can be kept in an optimal state.

S44: and if the compression ratio difference value meets the preset condition, determining that the actual compression ratio of the engine meets the requirement.

After determining whether a compression ratio difference between the expected compression ratio and the actual compression ratio meets a preset condition, if the compression ratio difference meets the preset condition, the actual compression ratio of the engine is determined to be close to the expected compression ratio, the engine is in an optimal compression ratio state, the actual compression ratio of the engine is determined to meet the requirement, a process of performing closed-loop regulation on the engine is exited, a normal operation mode of the engine is entered, and the actual compression ratio of the engine needs to respond according to normal requirements of a vehicle.

In this embodiment, according to the third preset data and the desired compression ratio, the target duty ratio of the hydraulic solenoid valve is determined, then the hydraulic solenoid valve is controlled according to the target duty ratio to perform PID control on the compression ratio of the engine, and in the PID control process, it is determined whether the compression ratio difference between the desired compression ratio and the actual compression ratio meets the preset condition, if the compression ratio difference meets the preset condition, it is determined that the actual compression ratio of the engine meets the requirement, and it is determined that the compression ratio of the engine is subjected to closed-loop adjustment, so that the actual compression ratio of the engine meets the specific process of the requirement, PID adjustment on the compression ratio of the engine is achieved based on the duty ratio of the hydraulic solenoid valve, and accurate and efficient control on the compression ratio of the engine is achieved.

In one embodiment, as shown in fig. 4, in the process of executing step S40, that is, in the process of performing closed-loop adjustment on the compression ratio of the engine, the method further specifically includes the following steps:

s401: the rate of change of the actual compression ratio is monitored to determine whether the rate of change is within a preset rate range.

In the process of performing closed-loop adjustment on the compression ratio of the engine, the actual compression ratio of the engine needs to be acquired in real time so as to monitor the change rate of the actual compression ratio, thereby determining whether the change rate is within a preset rate range.

The preset speed range is the allowable speed range of the compression ratio change of the engine under the current engine working condition; the maximum value of the preset speed range is the allowable maximum compression ratio change speed threshold delta epsilon r under the current engine working condition _max The minimum value of the preset speed range is the minimum compression ratio change speed threshold delta epsilon r allowed under the current engine working condition _min . The preset speed ranges under different engine working conditions are different, namely different speed ranges are provided under different rotating speeds and loads, namely the preset speed ranges are determined according to the real-time rotating speed and the actual load of the engine.

If the change rate of the actual compression ratio is greater than or equal to the minimum compression ratio change rate threshold value delta epsilon r _min And the change rate of the actual compression ratio is less than or equal to the maximum compression ratio change rate threshold value delta epsilon r _max Indicating that the rate of change of the actual compression ratio is within a safe range, there is no need to limit the rotational speed and torque of the engine. If the change rate of the actual compression ratio is smaller than the minimum compression ratio change rate threshold delta epsilon r _min Obtaining that the change rate of the actual compression ratio is larger than the maximum compression ratio change rate threshold delta epsilon r _max Determining that the change rate of the actual compression ratio is not in a safety range, wherein the change rate of the actual compression ratio is too fast, and possibly knocking and other safety risks occur, and limiting the rotating speed and the torque of the engine to stop the engine for ensuring the safety and the driving safety of the engine; at the same time, the engine needs to be controlled to give an alarm so as to enable users and users to And knowing the change condition of the actual compression ratio so as to perform corresponding processing.

S402: and if the change rate is in the preset rate range, controlling the engine to normally operate.

After monitoring the change rate of the actual compression ratio to determine whether the change rate is within a preset rate range, if the change rate is within the preset rate range, which means that the change rate of the actual compression ratio is within a safe range, the engine is controlled to normally operate without limiting the rotation speed and the torque of the engine, and the operation of closed-loop adjustment of the compression ratio of the engine is continuously performed until the closed-loop adjustment process is completed.

S403: and if the actual compression ratio is not in the preset speed range, limiting the rotating speed and the torque of the engine until the engine stops running.

After monitoring the change rate of the actual compression ratio to determine whether the change rate is within a preset rate range, if the actual compression ratio is not within the preset rate range, the change rate of the actual compression ratio is too fast, and safety risks such as knocking are possibly caused, and in order to ensure the safety and the driving safety of the engine, the rotation speed and the torque of the engine are required to be limited until the engine stops running, so that the driving safety is ensured.

In this embodiment, to reduce the data processing amount during the monitoring, it is necessary to monitor the rate of change of the actual compression ratio every interval period t (for example, 1 engine cycle). The calculation formula of the change rate of the actual compression ratio is as follows:

Δεr _n+1 ＝ε _n+1 -ε _n ；

wherein, deltaεr _n+1 The actual compression ratio determined for the n+1th cycle (e.g., n+1 engine cycles), i.e., the actual compression ratio of the current engine; epsilon _n The actual compression ratio determined for the nth cycle (e.g., n engine cycles), i.e., the actual compression ratio of the engine of the last cycle.

Taking the interval period t as 1 engine cycle as an example, in the current engine cycle, if the actual compression ratio changes at a rate of delta epsilon r _n+1 Greater than or equal to delta epsilon r _min And delta epsilon r _n+1 Less than or equal to delta epsilon r _max Indicating that the actual compression ratio change rate in the current engine cycle is in a safe range, and controlling the engine to normally operate without limiting the rotation speed and torque of the engine. If the actual compression ratio is changed at a rate of delta epsilon r _n+1 Less than delta epsilon r _min Or delta epsilon r _n+1 Equal to delta epsilon r _max The actual compression ratio is not in the preset rate range, which means that the change rate of the actual compression ratio is too fast, and that safety risks such as knocking can occur, and in order to ensure the safety of the engine and the driving safety, the rotation speed and the torque of the engine are required to be limited until the engine stops running.

The change rate of the actual compression ratio is monitored in each engine cycle to determine whether the change rate is within a preset rate range, and further different engine control strategies are executed according to the determination result so as to ensure driving safety.

In the embodiment, in the process of performing closed-loop adjustment on the compression ratio of the engine, the change rate of the actual compression ratio is monitored to determine whether the change rate is in a preset rate range, and if the change rate is in the preset rate range, the engine is controlled to normally operate; if the actual compression ratio is not in the preset speed range, limiting the rotation speed and torque of the engine until the engine stops running, monitoring the change speed of the actual compression ratio to determine whether the change speed is in the preset speed range, and executing different engine control strategies according to the determination result to ensure driving safety.

In an embodiment, before step S10, i.e. before determining the actual compression ratio of the engine, the method further specifically comprises the steps of:

s01: it is determined whether the compression ratio hydraulic system is malfunctioning.

After the vehicle is powered up, the ECU needs to determine whether the compression ratio hydraulic system has failed to implement an engine protection strategy based on the failure condition.

Wherein determining whether the compression ratio hydraulic system is malfunctioning comprises: after the vehicle is powered on, it is necessary to determine whether a phase sensor on a compression ratio control shaft in a compression ratio hydraulic system has failed and whether a hydraulic solenoid valve in the compression ratio hydraulic system has failed. If any device in the phase sensor and the hydraulic electromagnetic valve on the compression ratio control shaft fails, determining that the compression ratio hydraulic system fails; if the phase sensor and the hydraulic solenoid valve on the compression ratio control shaft are not faulty, the compression ratio hydraulic system is determined to be not faulty. When a phase sensor on the compression ratio control shaft fails, the accurate actual compression ratio of the engine cannot be obtained; when the hydraulic solenoid valve breaks down, the compression ratio of the engine cannot be controlled through the hydraulic solenoid valve, so that when any one of the phase sensor on the compression ratio control shaft and the hydraulic solenoid valve breaks down, the actual condition of the engine cannot be determined, and in order to ensure the safety of the engine and the driving safety, the compression ratio control system of the engine needs to be controlled to enter a fault mode, and the engine needs to be controlled to give an alarm, so that a user can know the fault condition of the compression ratio hydraulic system in time.

The method comprises the following steps of determining whether a phase sensor on a compression ratio control shaft in a compression ratio hydraulic system fails or not, wherein the body process is as follows: the ECU acquires the control shaft phase of the compression ratio control shaft after each power-on, and judges whether the acquired control shaft phase is normal or not; if the control shaft phase is smaller than the preset phase value, the control shaft phase is larger than the preset phase value, the control shaft phase is abnormal in value (such as no phase value) and other anomalies are generated, the phase sensor is determined to have an unreasonable signal fault. When the phase sensor fails unreasonably, the phase sensor is determined to fail, the engine cannot judge the phase condition of the current control shaft through the sensor, namely the current compression ratio state cannot be judged, the safety risk exists, the engine alarms, and meanwhile, the engine compression ratio control system enters a failure mode.

The method comprises the following steps of determining whether a hydraulic electromagnetic valve in a compression ratio hydraulic system fails or not, wherein the whole process is as follows: the ECU is electrified each time to carry out self-checking on the hydraulic electromagnetic valve, and judges whether the hydraulic electromagnetic valve is normal, if any fault such as hardware damage, incapability of electrifying, unreasonable signal and the like occurs on the electromagnetic valve, the hydraulic electromagnetic valve breaks down, the hydraulic electromagnetic valve can not receive an execution command fed back by the ECU to carry out phase maintaining and switching actions on the compression ratio control shaft, namely the compression ratio of the engine can not be maintained and switched, safety risks exist, the engine alarms, and meanwhile, the engine compression ratio control system enters a fault mode.

In the embodiment, the fault detection is performed on the hydraulic solenoid valve and the phase sensor on the compression ratio control shaft, so that whether the compression ratio hydraulic system breaks down or not is determined according to the fault detection results of the hydraulic solenoid valve and the phase sensor, the specific process of determining whether the compression ratio hydraulic system breaks down or not is clarified, and an accurate basis is provided for the follow-up engine control.

S02: and if the compression ratio hydraulic system does not have faults, acquiring the actual compression ratio of the engine.

After determining whether the compression ratio hydraulic system fails, if the compression ratio hydraulic system fails, the compression ratio of the engine can be regulated normally through the compression ratio hydraulic system, the actual compression ratio of the engine is obtained, a compression ratio evaluation parameter value is determined according to the actual compression ratio and the expected compression ratio, and the compression ratio of the engine is regulated according to the compression ratio evaluation parameter value.

S03: if the compression ratio hydraulic system fails, it is determined whether the compression ratio hydraulic system has a physical lock function.

After determining whether the compression ratio hydraulic system fails, if the compression ratio hydraulic system fails, the compression ratio of the engine cannot be adjusted through the compression ratio hydraulic system, and the engine has a safety risk, a fault prompt is sent to a user, and whether the compression ratio hydraulic system has a physical locking function is determined, so that different engine control strategies are executed according to a physical locking function judging result.

Wherein, determining whether the compression ratio hydraulic system has a physical locking function is performed by acquiring F of the vehicle _lock Signal value determination, F _lock Signal value under compressionAssignment is completed when the compression ratio mechanism of the ratio hydraulic system is completed. If F _lock Equal to 1, indicating that the compression ratio hydraulic system has a physical locking function; if F _lock Equal to 0 indicates that the compression ratio hydraulic system does not have a physical lock function.

S04: and if the compression ratio hydraulic system has a physical locking function, when a user has a vehicle demand, the compression ratio of the engine is controlled according to fourth preset data.

After determining that the compression ratio hydraulic system fails and determining whether the compression ratio hydraulic system has a physical locking function, if the compression ratio hydraulic system has the physical locking function, indicating that the compression ratio hydraulic system is still in a controllable state, sending confirmation information to a user so as to report the failure condition to the user and confirm whether the vehicle needs to be used continuously or not, if receiving a command of the user to continue to use the vehicle, determining that the user needs to acquire fourth preset data, and controlling the compression ratio of the engine according to the fourth preset data, so that the vehicle can safely run while the user needs to use the vehicle is met, and the safety of the user is ensured.

The fourth preset data are compression ratios of the fault mode engine under different working conditions, and the fourth preset data are calibrated in advance according to test data.

S05: if the compression ratio hydraulic system does not have the physical locking function, the engine stop operation is performed by limiting the rotation speed and torque of the engine.

After determining that the compression ratio hydraulic system fails and determining whether the compression ratio hydraulic system has a physical locking function, if the compression ratio hydraulic system does not have the physical locking function, the engine of the compression ratio hydraulic system is still in a controllable state, the rotation speed and the torque of the engine are limited through the control of parameters such as oil injection ignition, timing phase and the like, and finally the engine is smoothly stopped so as to avoid the damage of the engine and even safety accidents.

In the present embodiment, before determining the actual compression ratio of the engine, it is necessary to determine whether a malfunction occurs in the compression ratio hydraulic system; if the compression ratio hydraulic system does not have faults, acquiring the actual compression ratio of the engine; if the compression ratio hydraulic system fails, determining whether the compression ratio hydraulic system has a physical locking function; if the compression ratio hydraulic system has a physical locking function, when a user has a vehicle demand, the compression ratio control is carried out on the engine according to fourth preset data, the analysis processing process of the compression ratio of the engine in a fault mode is clarified, and when the compression ratio hydraulic system fails, a safe driving strategy is executed, so that the engine can be ensured to run safely or stop smoothly, safety accidents caused by vehicles and vehicle staff are avoided, and driving safety is ensured.

It should be understood that the sequence numbers of the steps in the above embodiments do not mean the order of execution, and the execution order of the processes should be determined by the functions and the internal logic, and should not be construed as limiting the implementation process of the embodiments of the present invention.

In one embodiment, an engine compression ratio control apparatus is provided, which corresponds to the engine compression ratio control method in the above embodiment one by one. As shown in fig. 5, the engine compression ratio control apparatus includes a first determination module 501, a second determination module 502, a third determination module 503, and an adjustment module 504. The functional modules are described in detail as follows:

a first determination module 501 for determining an actual compression ratio of the engine and determining a desired compression ratio of the engine;

a second determining module 502 for determining a compression ratio evaluation parameter value of the engine according to a desired compression ratio and an actual compression ratio of the engine;

a third determining module 503, configured to determine whether compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value;

the adjusting module 504 is configured to perform closed-loop adjustment on the compression ratio of the engine if the compression ratio of the engine needs to be adjusted, so that the actual compression ratio of the engine meets the requirement.

Further, in the process of performing closed-loop adjustment on the compression ratio of the engine, the adjustment module 504 is specifically further configured to:

Further, after determining the actual compression ratio of the engine, the first determination module 501 is further configured to:

Further, the first determining module 501 is specifically configured to:

Further, the second determining module 503 is specifically configured to:

Further, the compression ratio of the engine is controlled by a compression ratio hydraulic system comprising a hydraulic solenoid valve, the adjustment module 504 being specifically configured to:

Further, before determining the actual compression ratio of the engine, the first determination module 501 is specifically further configured to:

determining whether the compression ratio hydraulic system fails;

The specific limitation of the engine compression ratio control apparatus may be referred to as limitation of the engine compression ratio control method hereinabove, and will not be described in detail herein. The respective modules in the above-described engine compression ratio control apparatus may be implemented in whole or in part by software, hardware, or a combination thereof. The above modules may be embedded in hardware or may be independent of a processor in the computer device, or may be stored in software in a memory in the computer device, so that the processor may call and execute operations corresponding to the above modules.

In one embodiment, an engine compression ratio control apparatus is provided that includes a processor, a memory, and a database connected by a system bus. Wherein the processor of the engine compression ratio control apparatus is configured to provide computing and control capabilities. The memory of the engine compression ratio control device comprises a storage medium and an internal memory. The storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the storage media. The database of the engine compression ratio control device is used for storing first preset data, second preset data, third preset data, fourth preset data and the like. The computer program is executed by a processor to implement a method of controlling an engine compression ratio.

In one embodiment, as shown in fig. 6, there is provided an engine compression ratio control apparatus including a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the engine compression ratio control method described above when executing the computer program.

In one embodiment, a readable storage medium is provided having a computer program stored thereon, which when executed by a processor, implements the steps of the engine compression ratio control method described above.

Those skilled in the art will appreciate that implementing all or part of the above-described methods may be accomplished by way of a computer program stored in a computer-readable storage medium, which when executed, may comprise the steps of the above-described embodiments of the methods. Any reference to memory, storage, database, or other medium used in the various embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functions may be allocated to different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to complete all or part of the above-described functions.

The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.

Claims

1. An engine compression ratio control method, characterized by comprising:

determining an actual compression ratio of an engine and determining a desired compression ratio of the engine;

Determining a compression ratio evaluation parameter value of the engine according to a desired compression ratio and an actual compression ratio of the engine;

and if the compression ratio of the engine is required to be adjusted, performing closed-loop adjustment on the compression ratio of the engine so that the actual compression ratio of the engine meets the requirement.

2. The engine compression ratio control method according to claim 1, characterized in that in the process of performing closed-loop adjustment of the compression ratio of the engine, the method further comprises:

3. The engine compression ratio control method according to claim 1, characterized in that after the determination of the actual compression ratio of the engine, the method further comprises:

and if the actual compression ratio is not in the preset compression ratio range, limiting the rotation speed and the torque of the engine until the engine stops running.

4. The engine compression ratio control method according to claim 1, characterized in that the determining an actual compression ratio of an engine and determining a desired compression ratio of the engine includes:

determining an actual rotational speed and an actual load of the engine, and determining a control shaft phase of a compression ratio control shaft;

determining an actual compression ratio of the engine according to first preset data and the control shaft phase, wherein the first preset data is the compression ratio of the engine at different control shaft phase values in the actual working process;

5. The engine compression ratio control method according to claim 1, wherein the determining whether compression ratio adjustment of the engine is required or not based on the compression ratio evaluation parameter value includes:

When the compression ratio evaluation parameter value is a positive number, determining whether compression ratio adjustment is required to be performed on the engine according to the compression ratio evaluation parameter value and the first fluctuation threshold value;

and when the compression ratio evaluation parameter value is negative, determining whether the compression ratio adjustment of the engine is required according to the compression ratio evaluation parameter value and the second fluctuation threshold value.

6. The engine compression ratio control method according to any one of claims 1 to 5, characterized in that the compression ratio of the engine is controlled by a compression ratio hydraulic system including a hydraulic solenoid valve, the closed-loop adjustment of the compression ratio of the engine being made so that the actual compression ratio of the engine satisfies a demand, comprising:

determining a target duty ratio of the hydraulic solenoid valve according to third preset data, the expected compression ratio and the actual compression ratio, wherein the third preset data comprises different engine compression ratios and the corresponding hydraulic solenoid valve duty ratio of the engine compression ratio;

controlling the hydraulic solenoid valve according to the target duty ratio to perform PID control on the compression ratio of the engine;

In the PID control process, determining whether a compression ratio difference between the expected compression ratio and the actual compression ratio meets a preset condition;

7. The engine compression ratio control method according to any one of claims 1 to 5, characterized in that before the determination of the actual compression ratio of the engine, the method further comprises:

determining whether the compression ratio hydraulic system fails;

if the compression ratio hydraulic system does not have a fault, acquiring the actual compression ratio of the engine;

if the compression ratio hydraulic system has a physical locking function, when a user has a vehicle demand, the compression ratio of the engine is controlled according to fourth preset data, wherein the fourth preset data is the compression ratio of the engine under different working conditions in a fault mode.

8. An engine compression ratio control apparatus, characterized by comprising:

a first determination module to determine an actual compression ratio of an engine and to determine a desired compression ratio of the engine;

A second determination module that determines a compression ratio evaluation parameter value of the engine from a desired compression ratio and an actual compression ratio of the engine;

a third determination module configured to determine whether compression ratio adjustment of the engine is required based on the compression ratio evaluation parameter value;

9. An engine compression ratio control apparatus comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the engine compression ratio control method according to any one of claims 1 to 7 when executing the computer program.

10. A readable storage medium storing a computer program, characterized in that the computer program when executed by a processor implements the steps of the engine compression ratio control method according to any one of claims 1 to 7.