CN111271438A

CN111271438A - Hydraulic system for electric drive module of vehicle and control method

Info

Publication number: CN111271438A
Application number: CN202010075100.6A
Authority: CN
Inventors: 郝庆军; 陆中华; 耿建涛; 方伟; 王加乐; 陆诸军
Original assignee: Capotech Suzhou Co Ltd
Current assignee: Capotech Suzhou Co Ltd
Priority date: 2020-01-22
Filing date: 2020-01-22
Publication date: 2020-06-12

Abstract

The invention provides a hydraulic system, which relates to the technical field of cooling and lubrication, and is used for an electric drive module of a new energy vehicle, and the hydraulic system comprises an oil tank, an oil pump with bidirectional flow, a first control oil path and a second control oil path, wherein the first control oil path is connected with oil in the oil tank through a filter, the second control oil path distributes the oil to corresponding elements of the electric drive module after passing through an oil cooler, and the elements can be lubricated and cooled in real time under the full working condition state of the vehicle by controlling the rotation of the oil pump through a motor of the electric drive module; in addition, a control method based on the hydraulic system is further provided, the oil flow of each element can be dynamically adjusted by taking the flow area of the throttle valve, the differential pressure of the throttle valve and the oil density as relevant factors and configuring corresponding flow coefficients, and the lubricating and cooling efficiencies are improved.

Description

Hydraulic system for electric drive module of vehicle and control method

Technical Field

The invention relates to the technical field of lubrication and cooling, in particular to a hydraulic system for lubricating and cooling an electric drive module of a vehicle, and correspondingly relates to a control method for the hydraulic system.

Background

In recent years, with the global sales of new energy vehicles in an accelerated penetration state, the trend of electric driving is gradually clear, and a driving system of an electric driving module integrated by a motor and a gearbox is a key part of the new energy vehicles, and the driving system becomes a research focus in the industrial chain.

Generally, after a motor of a vehicle transmits power to a gearbox, in the power transmission process of the gearbox, a gear meshing point, gear oil stirring and bearing operation inside the gearbox generate certain power loss, so that the overall oil temperature of the gearbox or the local surface temperature of a shell is increased, and in order to ensure reliable operation of the gearbox and ensure that the highest operation temperature of the gearbox is within a design requirement value, the power loss point needs to be lubricated and cooled.

Chinese patent publication No. CN108626366A discloses a cooling and lubricating system for an automatic transmission including a three-way solenoid actuated valve, the system including a three-way solenoid actuated valve, at least one pump, a first fluid circuit for supplying oil to a first sub-system of the automatic transmission, and a second fluid circuit for supplying oil to a second sub-system of the automatic transmission, the two systems performing independent proportional flow control through the three-way solenoid actuated valve, but it has a disadvantage that it is only applicable to conventional internal combustion engine vehicles, a new energy vehicle drives the transmission to operate by mainly using different rotational directions through a motor in forward and reverse directions, while the conventional vehicle provides a fixed rotational direction through an engine, which makes the scheme inapplicable to the new energy vehicle, such that there may be a technical problem, in the reverse operating mode, the pump needs to be stopped, especially for commercial vehicles, which are often in a complex operating mode, and are often exposed to one or more of the following conditions: a) backing a car frequently; b) backing a car for a long distance; c) when the vehicle is started and backed after being stopped for a long time, the bearings, gears and the like of the electric drive module are worn and failed due to the fact that sufficient lubrication cannot be obtained, and therefore safety threats are caused to personnel.

German patent DE102013222752.3 discloses a fluid assembly which proposes a fluid pump having a first feed direction and a second feed direction, the fluid pump having two fluid pumps, each controlling a respective clutch assembly, which has the disadvantage that it only enables cooling of the clutch parts, and that it requires 3 different suction ports for the reservoir, which increases the complexity of the gearbox construction, and in addition the hydraulic control means according to the system will become very complex, otherwise oil blow-by is easy.

Disclosure of Invention

Aiming at the problem that full-working-condition lubrication and cooling cannot be realized for a new energy automobile in the prior art, the invention provides a hydraulic system for a vehicle electric drive module, which realizes forced lubrication and cooling of the vehicle electric drive module by driving an oil pump to act through a motor, and also provides a control method based on the hydraulic system.

A hydraulic system for an electric drive module of a new energy vehicle, comprising: an oil sump for collecting oil; the first end of the oil pump is connected with one end of the first control oil path, the second end of the oil pump is connected with one end of the second control oil path, and the oil pump provides power through a motor of the electric drive module; the first control oil path is provided with a filter, and the other end of the first control oil path extends into the oil groove; and the second control oil path is provided with an oil cooler, and the other end of the second control oil path is communicated with an element of the electric drive module.

Further, the device also comprises an electronic pump, wherein the electronic pump provides driving force through a small motor; the part of the first control oil path between the oil pump and the filter is provided with a first access point, the part of the second control oil path between the oil pump and the oil cooler is provided with a second access point, and the electronic pump is connected between the first access point and the second access point through a pipeline, wherein a first valve is arranged between the second access point and the electronic pump and used for limiting the oil to flow back to the electronic pump.

The oil filter further comprises a second valve connected with the filter in parallel on the first control oil path, one end of the second valve is connected between the first access point and the filter, and the other end of the second valve is connected between the filter and the tail end of the first control oil path.

Further, the end of the second control oil path is provided with a plurality of sub-lines, each sub-line is communicated with a corresponding element, and at least part of the sub-lines are provided with throttle valves.

A control method for a hydraulic system, during high speed travel in a vehicle, comprising the steps of: s1: a motor in the electric drive module rotates forwards to drive the oil pump to work, and oil is distributed to different elements through the filter, the oil pump and the oil cooler; s2: and a motor in the electric drive module rotates reversely to drive the oil pump to work, and oil passes through the filter, the oil pump and the oil cooler and is distributed to different elements.

Further, during the low-speed running process of the vehicle, the method also comprises the following steps: s3: in step S1 or S2, the small motor drives the electronic pump to operate, and provides auxiliary power to deliver the oil to the second control oil passage.

Further, the flow rate of the throttle is dynamically adjusted by a function Q ═ f (C, a, P, ρ), where C is the flow coefficient, a is the throttle flow area, P is the differential pressure of the throttle, and ρ is the oil density.

Further, the flow through function of the throttle valve

Regulation was performed where P1 is the throttle inlet pressure and P2 is the throttle outlet pressure.

Preferably, said C has a value of between 0.6 and 0.7.

Preferably, the value of C is 0.65.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects:

the hydraulic control system provided by the invention drives the oil pump to work by combining with a motor of the electric drive module, so that the oil pump can absorb oil in real time in the running process of a vehicle, and the oil pump is filtered by the filter and then is subjected to heat exchange by the oil cooler and then is provided to corresponding elements in the electric drive module, so that the lubricating requirements of the vehicle in any mode in the advancing and backing processes can be met.

Drawings

The above and other features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

fig. 1 is a schematic diagram of a hydraulic control system according to a first embodiment of the present invention.

Fig. 2 is a schematic view of another hydraulic control system disclosed in the first embodiment of the present invention.

Fig. 3 is a schematic diagram of a hydraulic control system according to a second embodiment of the present invention.

Detailed Description

The present invention will be described in more detail below with reference to the accompanying drawings, which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

As shown in fig. 1, the hydraulic control system provided by the present invention is suitable for the lubrication and cooling requirements of a new energy vehicle in a low-speed environment, and particularly, in any working mode that the vehicle realizes forward movement and reverse movement under a low-speed and high-torque condition, the new energy vehicle has a motor, the motor obtains electric energy from a battery and converts the electric energy into mechanical energy to provide power for vehicle driving, the motor is connected with a transmission, the transmission usually adopts a reduction gearbox or a multi-gear transmission, and the transmission and the motor can be distributed or integrated, but the transmission and the motor need to provide forward movement or reverse movement power for the vehicle depending on forward rotation (or clockwise rotation) and reverse rotation (or counterclockwise rotation) of the motor.

The motor or the transmission case has a rotating part such as a bearing, a gear, etc. on which a power transmission path is formed by rotation of the gear, and relative movement of the mutually connected parts is provided by rotation of the bearing, and in the present embodiment, such a part that can rotate during power transmission of the vehicle is referred to as an element.

In fig. 1, which discloses a sump 1, the sump 1 is located in the gearbox, typically arranged at the bottom of the gearbox, and the sump 1 contains oil for lubricating and cooling the elements in the gearbox.

Still include oil pump 2, fluid is in two-way flow can carry out in oil pump 2, oil pump 2 is the common device among the prior art, does not do further elaboration here to its self theory of operation. The oil pump 2 is connected with a driving shaft, the driving shaft is connected with the motor, namely, the motor rotates to drive the driving shaft to rotate, and then the oil pump 2 works.

One end of the oil pump 2 is connected with a first control oil path 21, and the terminal of the first control oil path 21 extends into the oil groove 1 and is contacted with oil in the oil groove 1; the other end of the oil pump 2 is connected with a second control oil path 22, and the oil pump 2 can pump oil in the oil groove 1 by driving of the motor, and corresponding elements are pumped into the oil groove through the first control oil path 21 and the second control oil path 22 so as to lubricate and cool the elements.

In order to ensure that the oil sucked into the first control oil passage 21 reaches a certain degree of cleanliness, the first control oil passage 21 is provided with a filter 4, the oil flowing through the first control oil passage 21 can be effectively filtered through the filter 4, and impurities in the oil of the whole hydraulic system can be reduced through the filter 4, so that the safety of the whole hydraulic system is protected.

In practice, since the filter 4 is likely to be clogged after a long-term use, at this time, the flow rate of the first control oil passage 21 becomes small, and in order to prevent the oil pump 2 and the electronic pump 3 from being damaged, a bypass valve 6 is connected to the first control oil passage 21, and specifically, one end of the bypass valve 6 is connected between the first connection point and the filter 4, and the other end is connected between the filter 4 and the end of the first control oil passage 21, so that the bypass valve 6 and the filter 4 are connected in parallel on the first control oil passage, and preferably, as shown in fig. 1, one end of the bypass valve 6 is directly connected to the first connection point, so that when the filter 4 is clogged or the flow rate becomes small, the communication of the oil can be achieved by opening the bypass valve 6.

Further, fig. 1 also discloses an electronic pump 3, the electronic pump 3 is connected with a small motor 31, one end of the electronic pump 3 is connected with the first control oil path 21, and the other end is connected with the second control oil path 22, specifically, a first access point is arranged at a portion of the first control oil path 21 between the oil pump 2 and the filter 4, and an inlet of the electronic pump 3 is connected to the first access point through a first branch; the second control oil path 22 is provided with a second access point, an outlet of the electronic pump 3 is connected to the second access point through a second branch, when the motor and the small motor 31 operate together, the oil filtered by the filter 4 can distribute a part of the oil to the electronic pump 3 on the first control oil path 21, and is injected into the second control oil path 22 through pressurization of the electronic pump 3, so that the oil pressure in the second control oil path 22 is increased.

Install oil cooler 5 on the second control oil circuit 22, oil cooler 5 is located the low reaches position of second access point, electronic pump 3 and/or oil pump 2 will fluid pump income extremely behind the second control oil circuit 22, through during oil cooler 5, oil cooler 5 can utilize the coolant liquid carries out the heat exchange with fluid to take away the heat in the fluid, realize the cooling treatment to fluid, utilize an oil cooler 5 can realize simultaneously in this embodiment to come from electronic pump 3 with the fluid of oil pump 2 carries out the processing of cooling down jointly, guarantees fluid on the second control oil circuit 22 is in uniformly low temperature state.

Fig. 2 shows a diagram of a hydraulic control system of the present invention, wherein fig. 2 exemplarily discloses elements requiring lubrication inside a motor and a transmission, which are respectively a plurality of gears (e.g., a meshing gear 1, a meshing gear 2, a meshing gear 3) and a plurality of bearings (a bearing 1, a bearing 2, a bearing 3), each gear and each bearing have a corresponding pipeline, inlet sides of the pipelines are commonly connected with an end of the second control oil path 22, oil passing through a pressurizing and cooling outlet path is distributed to each pipeline by the second control oil path 22 to realize lubrication and cooling of the elements, after lubricating and cooling the elements, the high temperature generated by the elements can be sucked away and flows back to the oil groove 1 through an oil passage in the gearbox or the motor, therefore, the circulation lubrication and cooling can be realized, and the condition that the motor and elements in the gearbox are always in a temperature controllable state is ensured.

In the embodiment, the working characteristics of the new energy automobile are researched, the new energy automobile and the oil pump 2 are skillfully combined, namely, the oil pump 2 is driven to act by the forward rotation energy and the reverse rotation energy of the motor, so that forced lubrication of the vehicle in the existing hydraulic system can be realized in the working mode of backing the vehicle, the whole system does not need to adopt a redundant design, a control circuit is simple and effective, and thus in the environment with the same oil, the first control oil way 21 and the second control oil way 22 have shorter paths and have lower pressure on the oil pump 2, namely, compared with the traditional oil pump 2, the oil pump 2 with smaller volume or lower price can be selected in the embodiment, thereby being beneficial to reducing the volume of a speed change system and lowering the system cost.

Certainly, the vehicle backs a car under the low-speed state, especially backs a car continuously when starting, and its requirement to lubrication and cooling is extremely high, and the work that only relies on oil pump 2 at this moment obviously can not satisfy the demand of system, though can solve some problems by increasing the volume of oil pump 2 or selecting higher performance oil pump 2, its design demand that does not accord with the gearbox nevertheless, its reason lies in that whole car manufacturer has the severe restriction to the volume of gearbox, therefore need consider how to promote oil circuit pressure under the prerequisite of using the very little oil pump 2 of volume.

In this embodiment, combine fig. 1, it chooses for use electronic pump 3 to provide auxiliary pressure, and it is important electronic pump 3 with oil pump 2 parallel operation can carry out the cooperation, specifically, in this embodiment electronic pump 3 with oil pump 2 is parallel state, and its advantage still lies in can realizing safe effect, can guarantee that system lubrication and cooling function can not lose in the twinkling of an eye when wherein arbitrary device breaks down, reduces the safety risk of whole car.

However, the auxiliary boosting by the electronic pump 3 alone is not reliable, mainly because the output power of the electronic pump 3 is significantly limited compared to the oil pump 2, and the transmission itself does not have extra space to accommodate the electronic pump 3 with a larger volume, and if the electronic pump 3 is operated only in parallel with the oil pump 2, there is a problem that: under the low temperature operating mode, fluid viscosity can the grow, and the resistance in the hydraulic control system can sharp grow, and electronic pump 3 can't carry out high-efficient work under this kind of operating mode, and the fault rate is higher moreover.

In this embodiment, the check valve 32 is disposed on the second branch, the electronic pump 3 can be isolated from the first control oil path 21 and the second control oil path 22 by the check valve 32, when the vehicle is started and the temperature of the oil rises to a certain value, the electronic pump 3 is started to operate, and at this time, the oil can be pressurized and injected into the second control oil path 22 through the check valve 32, so that the dynamic cooling adjustment function of the vehicle under the low-speed and high-torque working condition can be realized, and in addition, the check valve 32 can prevent the oil of the oil pump 2 from flowing back to the electronic pump 3.

As shown in fig. 3, a hydraulic control system according to a second embodiment of the present invention is adapted to the lubrication and cooling requirements of new energy vehicles in medium and high speed environments, and in accordance with the first embodiment, fig. 3 also shows an oil sump 1, wherein the oil sump 1 is located in the transmission, and is generally arranged at the bottom of the transmission, and the oil sump 1 contains oil for lubricating and cooling the components in the transmission.

Likewise, an oil pump 2 is further included, and the oil can flow bidirectionally in the oil pump 2. The oil pump 2 is connected with a driving shaft, the driving shaft is connected with the motor, namely the driving shaft can be driven to rotate through the rotation of the motor, the driving shaft can rotate forwards or backwards, the oil pump 2 can automatically adjust the eccentric distance direction of an inner rotor and an outer rotor, and therefore the positions of an oil inlet and an oil outlet of the oil pump 2 are kept unchanged.

In practice, since the filter 4 is likely to be clogged after a long-term use, the flow rate of the first control oil passage 21 is reduced, and in order to prevent the oil pump 2 from being damaged, a bypass valve 6 is connected to the first control oil passage 21, specifically, one end of the bypass valve 6 is connected between the first connection point and the filter 4, and the other end is connected between the filter 4 and the end of the first control oil passage 21, so that the bypass valve 6 and the filter 4 are connected in parallel on the first control oil passage, and preferably, as shown in fig. 2, one end of the bypass valve 6 is directly connected to the first connection point, so that when the filter 4 is clogged or when the flow rate is reduced, the bypass valve 6 is opened to allow the oil to be conducted

Install oil cooler 5 on the second control oil circuit 22, oil cooler 5 is located the low reaches position of second access point, fluid through the suction and through the pressure boost enter into behind the second control oil circuit 22, the rethread during oil cooler 5, oil cooler 5 can utilize coolant liquid and fluid carry out the heat exchange to take away the heat in the fluid, realize the cooling treatment to fluid, guarantee fluid on the second control oil circuit 22 is in low temperature state uniformly.

With reference to fig. 2, the elements requiring lubrication inside the motor and the transmission are exemplarily disclosed, and there are a plurality of gears (e.g., the meshing gear 1, the meshing gear 2, the meshing gear 3) and a plurality of bearings (e.g., the bearing 1, the bearing 2, the bearing 3), each gear and each bearing has a corresponding pipeline, inlet sides of the pipelines are commonly connected to an end of the second control oil path 22, the oil passing through the pressurization and cooling outlet is distributed to each pipeline by the second control oil path 22, so as to lubricate and cool the elements, and after lubricating and cooling the elements, the oil can suck high temperature generated by the elements and flow back to the oil groove 1 through the transmission or the oil path inside the motor, so as to achieve cyclic lubrication and cooling, and ensure that the motor and the elements inside the transmission are always in a temperature controllable state.

In summary, the vehicle can lubricate and cool the elements of the gearbox and the motor in real time under different working modes whether the vehicle is in a low speed state or a medium-high speed state.

In order to further improve the lubricating and cooling effects, the invention also provides a hydraulic control method, wherein the pipelines at the terminal of the second control oil path 22 are provided with throttle valves 7, each throttle valve 7 corresponds to a corresponding element, and the hydraulic control is carried out by adopting the following method in the first embodiment:

s1: a motor in the electric drive module rotates forwards to drive the oil pump 2 to work, and oil is distributed to different elements through the filter 4, the oil pump 2 and the oil cooler 5; s2: a motor in the electric drive module rotates reversely to drive the oil pump 2 to work, and oil is distributed to different elements through the filter 4, the oil pump 2 and the oil cooler 5; during the low-speed running process of the vehicle, the method further comprises the following steps: s3: in step S1 or S2, the small electric motor 31 drives the electronic pump 3 to operate, and provides auxiliary power to deliver the oil to the second control oil passage 22.

In a second embodiment, the following method is used for hydraulic control: s1: a motor in the electric drive module rotates forwards to drive the oil pump 2 to work, and oil is distributed to different elements through the filter 4, the oil pump 2 and the oil cooler 5; s2: the motor in the electric drive module rotates reversely to drive the oil pump 2 to work, and oil passes through the filter 4, the oil pump 2 and the oil cooler 5 to be distributed to different elements.

In practice, due to the temperature disparity between different components, the desired lubrication and cooling effect may not be achieved by using an equal distribution, for example, the temperature of the meshing gears and bearings during operation may be different, the cooling and lubrication requirements may also be different, and the cooling and lubrication requirements may also be different when the same component is installed at different positions.

The present embodiment establishes the relevant function according to the characteristics of the throttle valve 7: q ═ f (C, a, P, ρ), where C is the flow coefficient, a is the flow area of the throttle valve 7, P is the differential pressure of the throttle valve 7, and ρ is the oil density, i.e., the flow coefficient, the flow area of the throttle valve 7, the differential pressure of the throttle valve 7, and the oil density are taken into consideration to effect control of the throttle valve 7.

Further, the flow rate of the throttle valve 7 passes through a function

The regulation is carried out, wherein P1 is the pressure at the inlet of the throttle valve 7, and P2 is the pressure at the outlet of the throttle valve 7, so that each throttle valve 7 can dynamically output the required oil according to the considered factors, and the elements are ensured to meet the preset temperature requirement respectively.

In one embodiment, the flow coefficient C may be a two-dimensional table based on the relationship between temperature and coefficient, such as:

TABLE 1 two-dimensional table of temperature and coefficient

Temperature of	Corresponding flow coefficient
		＜10℃	0.60
10℃～20℃	0.62
		20℃～30℃	0.65
30℃～40℃	0.67
		＞40℃	0.70

The required flow coefficient can be inquired in real time by establishing the relation between the temperature and the coefficient, and the output flow can be corrected and adjusted.

In the same way, the linear relation between the temperature and the coefficient can be established for dynamic correction and adjustment, and the accuracy of output is ensured.

In addition, in this embodiment, because of the pressure at the inlet side and the outlet side of the flow valve 7 according to the pressure difference, the conditions such as the temperature of the current element can be further fed back from the angle of the pressure, and the required flow rate can be simulated, which is equivalent to the confirmation and dynamic adjustment of the condition of the current element from the angle of the dual action of the flow rate coefficient and the pressure difference, and the precision of lubrication and cooling is further ensured.

In practice, the conventional lubricating oil may be counted and tested according to the two-dimensional table, in this embodiment, a plurality of lubricating oils are tested and the average value is determined, and then the lubricating oil may be adjusted by a fixed value, for example, 0.65 is used as a fixed adjustment coefficient.

In a word, through above technical scheme, can carry out accurate control to the flow to carry out the developments according to the operating mode of reality and adjust the flow, make different components all can be in reasonable temperature interval.

It will be appreciated by those skilled in the art that the invention can be embodied in many other specific forms without departing from the spirit or scope of the invention. Although embodiments of the present invention have been described, it is to be understood that the present invention should not be limited to those embodiments, and that changes and modifications may be made by one skilled in the art within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A hydraulic system for an electric drive module of a new energy vehicle, comprising: an oil sump for collecting oil; it is characterized by also comprising:

the first end of the oil pump is connected with one end of the first control oil path, the second end of the oil pump is connected with one end of the second control oil path, and the oil pump provides power through a motor of the electric drive module;

the first control oil path is provided with a filter, and the other end of the first control oil path extends into the oil groove;

and the second control oil path is provided with an oil cooler, and the other end of the second control oil path is communicated with an element of the electric drive module.

2. The hydraulic system as recited in claim 1 further comprising an electronic pump providing a driving force through a small electric motor; the part of the first control oil path between the oil pump and the filter is provided with a first access point, the part of the second control oil path between the oil pump and the oil cooler is provided with a second access point, the electronic pump is connected between the first access point and the second access point through a pipeline, a first valve is arranged between the second access point and the electronic pump, and the first valve limits oil to flow back to the electronic pump.

3. The hydraulic system as claimed in claim 2, further comprising a second valve connected in parallel with the filter on the first control oil path, wherein one end of the second valve is connected between the first connection point and the filter, and the other end of the second valve is connected between the filter and the end of the first control oil path.

4. A hydraulic system according to claim 1 or 2, wherein the second control circuit is provided at its end with a plurality of sub-circuits, each communicating with a corresponding component, and at least some of the sub-circuits are provided with a throttle.

5. A control method of a hydraulic system according to any one of claims 1-4, characterized by comprising the steps of:

s1: a motor in the electric drive module rotates forwards to drive the oil pump to work, and oil is distributed to different elements through the filter, the oil pump and the oil cooler;

s2: and a motor in the electric drive module rotates reversely to drive the oil pump to work, and oil passes through the filter, the oil pump and the oil cooler and is distributed to different elements.

6. The control method according to claim 5, characterized by further comprising the steps of:

s3: in step S1 or S2, the small motor drives the electronic pump to operate, and provides auxiliary power to deliver the oil to the second control oil passage.

7. The control method according to claim 5 or 6, characterized in that the flow rate of the throttle is dynamically adjusted by a function Q ═ f (C, a, P), where C is the flow coefficient, a is the throttle flow area, P is the differential pressure of the throttle, and P is the oil density.

8. The control method of claim 7, wherein the flow through function of the throttle valve

9. Control method according to claim 8, characterized in that the value of C is between 0.6 and 0.7.

10. The control method according to claim 9, wherein the value of C is 0.65.