CN118306920A - Control system and control method of hydraulic traction machine - Google Patents

Abstract

The invention relates to a control system and a control method of a hydraulic tractor, which regulate and control the starting, working and stopping processes of the hydraulic tractor, and when an equipment operator pulls an operating handle to start traction operation, no matter how fast the operating handle is opened and how large the actual opening is, no matter how large the load born on a winding drum is, the hydraulic pump can stably start with load, and can provide sufficient power, so that the severe fluctuation of the pressure at the moment of starting is avoided, and the phenomenon of the instant rollback of the winding drum caused by the load is avoided; in the traction operation process, when the opening of the operating handle is kept unchanged, the traction machine can keep constant-speed traction and is not influenced by external load change; when the traction operation is stopped, no matter how fast the operation handle is reset, the safe stopping operation without impact can be realized, and the situation of severe pressure impact caused by too fast braking of the brake or reel slipping caused by too slow braking of the brake is avoided.

Description

Control system and control method of hydraulic traction machine

Technical Field

The invention relates to the technical field of hydraulic control, in particular to a control system and a control method of a hydraulic tractor.

Background

The hydraulic traction machine generally adopts a combined transmission mode of a hydraulic closed system and an open hydraulic system, and the hydraulic power system mainly comprises an engine, an electric proportion bidirectional hydraulic pump, a hydraulic motor, an electromagnetic reversing valve and the like, wherein the hydraulic motor drives a winding drum to bidirectionally rotate through a speed reducer and a gear pair, and reliable braking is realized through a brake connected to the speed reducer. When the traction operation is needed, the hydraulic pump works, the brake is opened, the hydraulic motor is driven to drive the winding drum to rotate, when the traction operation is stopped, the hydraulic pump is controlled to stop working, the hydraulic motor stops rotating, meanwhile, the brake is combined, external load is borne by the brake, and the winding drum is ensured to be in a safe stop state. From the above description working conditions, the working of the hydraulic pump and the hydraulic motor and the opening and closing of the brake are shown in linkage relation, and from the practical use requirement, the two actions need to be matched accurately, and the pulling control of the corresponding control handle is adopted to realize stable, safe and reliable traction operation or stop braking operation.

There are two problems with conventional tractors:

When the tractor starts to draw, a certain load is possibly brought when the tractor stops working last time, and the situation that the instantaneous pressure is severely fluctuated and the winding drum slides back easily due to insufficient starting power, and even flameout is caused due to insufficient power, so that certain potential safety hazard exists;

When the tractor is stopped, the brake is braked prematurely, so that certain pressure impact is caused to the brake; the brake is braked too late, so that the condition of reel back slip can occur.

Disclosure of Invention

Therefore, the invention aims to solve the technical problems of the prior art when the tractor starts, works and stops working, and provides a control system and a control method for the hydraulic tractor, which regulate and control the starting, working and stopping processes of the hydraulic tractor, ensure that the hydraulic tractor can start stably, draw at a constant speed and stop working safely.

In order to solve the technical problems, the invention provides a control method of a hydraulic tractor, which comprises the following steps:

starting traction operation:

S1, operating a handle from a middle position to a traction position at any opening degree and at any pulling speed, controlling the displacement of a hydraulic pump by using a variable current value I1, gradually increasing the variable current value I1 in a calibrated time-dependent incremental mode, gradually increasing the working pressure of the hydraulic pump at the moment, and starting a pre-pressurizing process;

S2, acquiring a real-time pressure value C of the hydraulic pump in the process of gradually increasing the pressure of the hydraulic pump, comparing the pressure value C with a pressure calibration value C2 in a nonvolatile memory, and controlling a brake electromagnetic valve to be electrified when the pressure value C is greater than or equal to the pressure calibration value C2, opening a brake, and starting the hydraulic motor to rotate and gradually accelerate;

S3, acquiring a real-time rotating speed n of the hydraulic motor in the process of gradually increasing the rotating speed of the hydraulic motor, comparing the real-time rotating speed n with a calibrated motor stable working rotating speed n1 of the hydraulic motor, and when the real-time rotating speed n is larger than or equal to a rotating speed calibration value n1, completing a stable starting process by a traction system, wherein the control current of the hydraulic pump is switched from a variable current value I1 to a hydraulic pump control current I2 corresponding to the opening of a current handle;

Continuous constant speed traction operation:

S4, proportionally calculating a target traction speed V1 from the opening of a current handle as a target value, proportionally calculating the actual rotation speed measured by a rotation speed sensor to obtain the current traction speed V as a feedback value, calculating the deviation of V1 and V, dynamically adjusting a hydraulic pump control current I2 by adopting a PID (proportion integration differentiation) regulation closed-loop control mode to enable the deviation of V1 and V to approach 0, wherein the tractor is in a constant-speed traction state, and repeating the above processes when an operator changes the opening of a control handle, and re-realizing constant-speed traction operation according to the changed opening of the handle;

stopping the traction operation:

s5, operating the handle to return to the middle position at any opening degree and at any pulling speed, and recovering the control current of the hydraulic pump to 0, wherein the hydraulic pump stops outputting hydraulic oil at the moment, the rotating speed of the hydraulic motor is gradually reduced, and the speed of the reduction is related to the load of the current winding drum;

S6, when the handle closing switch is triggered, acquiring a real-time pressure value C of the hydraulic pump, writing the pressure value C into a nonvolatile memory to obtain a stored value C1, and calculating according to the stored value C1 to obtain a pressure calibration value C2 in the nonvolatile memory when the hydraulic pump is started next time;

And S7, acquiring the real-time rotating speed n of the hydraulic motor in the process of gradually reducing the rotating speed of the hydraulic motor, comparing the real-time rotating speed n with a steady stopping rotating speed calibration value n2 of the hydraulic motor, and controlling the brake electromagnetic valve to lose electricity when the real-time rotating speed n is smaller than or equal to the rotating speed calibration value n2, so that the brake is braked steadily.

In one embodiment of the invention, when the traction operation is started, after the handle is started at any opening, an engine throttle rotation speed value E1 is calculated and controlled according to a pressure calibration value C2 in a nonvolatile memory, the throttle rotation speed value E1 is sent to an engine controller through a CAN bus, so that the engine provides a rotation speed matched with the pressure calibration value C2 in the nonvolatile memory, after a brake is opened, the engine rotation speed is positively related to the opening proportion of the handle, and as the pulling angle of the handle is gradually increased, the engine rotation speed proportion is increased, and the rotation speed of a winding drum is matched and adjusted.

In one embodiment of the invention, when the traction stopping operation is executed, after the handle is reset, the throttle rotating speed value E1 of the engine is calculated according to the recalculated pressure calibration value C2 in the nonvolatile memory, the throttle rotating speed value E1 is sent to the engine controller through the CAN bus, the engine is reduced to the rotating speed matched with the pressure calibration value C2 in the nonvolatile memory, after the brake is braked, the rotating speed of the engine is reduced to the standby rotating speed, and the standby rotating speed is regulated through the throttle potentiometer.

In one embodiment of the present invention, in step S1, the handle is used as an input of a traction operation control signal, and one voltage proportion signal and two direction signals are provided as inputs, wherein the direction signals are switching value signals for controlling operation, stopping and operation directions, and the voltage proportion signal is adjusted according to the change of the opening degree of the handle.

In one embodiment of the invention, in step S2 and step S6, a pressure sensor is used to obtain a real-time pressure value C of the hydraulic system.

In one embodiment of the invention, in step S3 and step S7, a speed sensor is used to obtain the real-time speed n of the hydraulic motor.

In one embodiment of the present invention, in step S3, the process of dynamically adjusting the output current value is: PWM current reference value I2 is calculated according to parameters of handle opening, engine rotating speed and equipment transmission ratio, and meanwhile, the difference between target traction speed V1 and actual traction speed V is used as a target value and a feedback value of PID regulation, and hydraulic pump control current I2 is dynamically regulated to enable deviation of V1 and V to approach 0.

In one embodiment of the invention, the on-off of an oil way in the brake is controlled through an electromagnetic valve, the electromagnetic valve is electrified, the oil way is conducted, the brake is opened, and the winding drum can rotate; the electromagnetic valve is powered off, the oil way is closed, the brake is combined, and the winding drum cannot rotate.

In one embodiment of the present invention, when performing a constant-speed traction operation, a traction preset value is set by a traction preset potentiometer, and a corresponding pressure value C3 is calculated according to the preset value; in the traction process, if the traction force suddenly decreases, the traction machine continues to run at a target traction speed V1 calculated by the opening degree of the handle; if the traction force suddenly increases, when the real-time pressure value C measured by the pressure sensor is greater than the preset pressure value C3, steps S5 to S7 are performed.

In order to solve the technical problem, the invention also provides a control system of the hydraulic tractor, which can complete the control method, and comprises the following steps:

A controller capable of executing the above control method;

The hydraulic pump is an electric proportional variable pump, is integrated with a bidirectional proportional electromagnetic valve, and can control the opening of the electromagnetic valve through proportional current input to realize different displacement adjustment of the hydraulic pump;

the hydraulic motor is connected with the winding drum through a speed reducer and a gear pair and drives the winding drum to rotate;

the engine is connected with the hydraulic pump, and is used for converting the work of the hydraulic pump into the pressure energy of the hydraulic system by driving the hydraulic pump to rotate so as to provide energy supply for the hydraulic system;

The brake is used for transferring the external load on the winding drum to a mechanical structural part of the equipment, and when the brake brakes reliably, the hydraulic pump is in a low-pressure standby state;

The electromagnetic valve is a two-position three-way electromagnetic reversing valve and is used for controlling the on-off of an oil path of a brake so as to control the opening and the closing of the brake, and after the brake is opened, the external load on the winding drum is born and driven by a hydraulic motor to realize the traction or wire feeding operation of the tractor;

the pressure sensor is arranged at a working oil port of the hydraulic pump and is used for measuring the real-time pressure of the hydraulic pump, and the pressure measured by the pressure sensor is positively correlated with the external load born by the winding drum at present;

The rotating speed sensor is arranged on the hydraulic motor and is connected with the controller through a cable and is used for measuring the real-time rotating speed of the hydraulic motor;

The handle is used as an input element of a traction operation control signal, is connected with the controller through a cable, provides input of a voltage proportion signal and two direction signals, and the direction signals are switching value signals and are used for controlling operation, stopping and operation directions;

The throttle potentiometer is connected with the controller through a cable and is used for setting the rotating speed of the engine;

and the traction preset potentiometer is connected with the controller through a cable and is used for setting the maximum traction of the equipment.

Compared with the prior art, the technical scheme of the invention has the following advantages:

the control method of the hydraulic tractor regulates and controls the starting, working and stopping processes of the hydraulic tractor, ensures that the hydraulic tractor can start stably and draw at a constant speed under the condition of completely not depending on the working experience and the control mode of operators, and can stop working safely and stably without impact.

When traction operation is started, setting a controlled initial current value which is started at a fixed value and is increased gradually along with time to control the displacement of the hydraulic pump, so that no matter how the handle is operated at an opening, the pressure of the hydraulic pump is controlled to be gradually increased by a current which changes along with the current operation state of the equipment, the rapidity and the stability of the hydraulic pump are independent of the actual operation mode of an operator based on the control capability of the controller, the pressure value of the hydraulic pump is collected in real time in the process of gradually increasing the pressure, the pressure value is compared with the pressure calibration value in a nonvolatile memory, the pressure calibration value in the nonvolatile memory is calculated according to the load pressure value of the last stop, the brake is controlled to be opened only when the pressure value is larger than the pressure calibration value, the pressure of the hydraulic system can be accurately matched with the current load of a winding drum at the moment, and severe impact caused by the instant transfer of the heavy load to the hydraulic system by the equipment frame is avoided;

After the brake is opened, in order to ensure that the opening of the handle can be matched with the speed of the hydraulic motor, the real-time rotating speed of the hydraulic motor is acquired in the process that the rotating speed of the hydraulic motor is gradually increased, the real-time rotating speed is compared with a rotating speed calibration value of the hydraulic motor, the rotating speed calibration value is set according to the actual requirement of the tractor, when the real-time rotating speed is larger than the rotating speed calibration value, the tractor is indicated to finish stable starting, at the moment, the output current value is stably switched to a calculated value corresponding to the opening of the handle, and closed-loop control is formed by combining the deviation of the target speed and the feedback speed, so that the rotating speed of the hydraulic motor is consistent with the traction speed target value.

Under the control logic, no matter how the opening of the operating handle is, no matter how large the load is borne on the winding drum, the load can be stably started, the hydraulic system can provide sufficient and timely power, the severe fluctuation of the pressure at the moment of starting cannot be caused, the phenomenon that the winding drum slips back because the response of the hydraulic system is delayed and the load cannot be matched in time cannot be caused, and in the continuous traction operation process, no matter the load changes, the traction speed always ensures that the target traction speed corresponding to the opening of the handle tends to be consistent.

When traction operation is carried out, the control system reasonably configures the working rotating speed of the diesel engine based on the current storage value in the nonvolatile memory and the opening of the real-time handle, and dynamically adjusts the output current value to control the displacement of the hydraulic pump, so that the actual traction speed always tends to be consistent with a traction speed target value given by the control handle, constant-speed traction is automatically maintained without being influenced by load change, and when an operator changes the opening of the handle, the adjustment method is repeated, and the hydraulic pump rapidly responds according to the new opening and reenters constant-speed traction;

When the traction operation is stopped, the brake is closed at the first time when the handle is restored to the middle position, the reel stops rotating, but the control current of the hydraulic pump is reduced rapidly according to the zeroing of the handle proportion, after the hydraulic pump is stopped, the rotating speed of the hydraulic motor is reduced rapidly under the action of an external load, the real-time rotating speed of the hydraulic motor is obtained in the process, the rotating speed calibration value is close to zero compared with the steady braking rotating speed calibration value of the hydraulic motor, the test calibration can be carried out according to equipment with specific specifications, and when the real-time rotating speed is smaller than or equal to the rotating speed calibration value, the brake is controlled to brake, so that the completely impact-free safe stop operation can be realized no matter whether an operator operates the handle or operates the handle severely, and the reel slip caused by the pressure impact caused by too fast braking of the brake or the too slow braking of the brake is avoided.

Drawings

In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which:

FIG. 1 is a step diagram of a method of controlling a hydraulic traction machine of the present invention;

FIG. 2 is a flow chart of the hydraulic tractor of the present invention initiating a traction operation;

fig. 3 is a flow chart of the hydraulic traction machine of the present invention stopping the traction operation.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.

Example 1

When the hydraulic traction machine is controlled to work, three working conditions mainly exist, namely: the invention discloses a control method of a hydraulic tractor, which comprises the following steps of starting the tractor, carrying out constant-speed traction operation and stopping the tractor, wherein the control method comprises the following steps of:

starting traction operation:

S1, operating a handle from a middle position to a traction position at any opening degree and at any pulling speed, controlling the displacement of a hydraulic pump by a variable current value I1, wherein the value of I1 is between an Imin and an Imax, the Imin is an initial value which can be responded and operated by the hydraulic pump, the displacement of the hydraulic pump corresponding to the Imax can ensure that the pressure is built up, the corresponding reel rotating speed is larger than a calibrated motor stable working rotating speed n1, the value of I1 starts from the Imin, and gradually increases according to a calibrated time-related increasing mode, and the working pressure of the hydraulic pump gradually rises to start a pre-pressurizing process.

S2, acquiring a real-time pressure value C of the hydraulic pump through a pressure sensor in the process of gradually increasing the pressure of the hydraulic pump, comparing the pressure value C with a pressure calibration value C2 in a nonvolatile memory (the C2 is calibrated to be 0 when the program is downloaded for the first time), controlling a brake electromagnetic valve to be electrified when the pressure value C is greater than or equal to the pressure calibration value C2, opening a brake, and starting the hydraulic motor to rotate and gradually accelerate.

S3, acquiring a real-time rotating speed n of the hydraulic motor through a rotating speed sensor in the process of gradually increasing the rotating speed of the hydraulic motor, comparing the real-time rotating speed n with a calibrated motor stable working rotating speed n1 of the hydraulic motor, and finishing a stable starting process of the traction system when the real-time rotating speed n is greater than or equal to a rotating speed calibration value n1, wherein the control current of the hydraulic pump is stably and rapidly switched from I1 to a hydraulic pump control current I2 corresponding to the opening of the current handle.

Continuous constant speed traction operation:

S4, the target traction speed V1 can be proportionally calculated from the opening of the current handle as a target value, the actual rotation speed measured by the rotation speed sensor can be proportionally calculated to obtain the current traction speed V as a feedback value, the deviation of V1 and V is calculated, the hydraulic pump control current I2 is dynamically adjusted by adopting PID regulation or other feasible closed-loop control modes, the deviation of V1 and V approaches 0, at the moment, the tractor is in a constant-speed traction state, when an operator changes the opening of the control handle, the process is repeated, and the constant-speed traction operation is realized again according to the changed opening of the handle.

Stopping the traction operation:

S5, operating the handle to return to the middle position at any opening degree and at any pulling speed, triggering the middle position switch, changing the corresponding switching value from TRUE to FALSE, and controlling the current to be restored to 0 by the hydraulic pump, wherein the hydraulic pump stops outputting the hydraulic oil at the moment, the rotating speed of the hydraulic motor is gradually reduced, and the speed of the reduction is related to factors such as the load of the current winding drum.

S6, when the handle closing switch is triggered, acquiring a real-time pressure value C of the hydraulic pump, writing the pressure value C into a nonvolatile memory (replacing the original stored 0 value), namely a stored value C1, calculating according to the stored value C1 to obtain a pressure calibration value C2 in the nonvolatile memory when the hydraulic pump is started next time, wherein the pressure calibration value C2 is generally less than or equal to C1, the difference value (C1-C2) of the pressure calibration value is positively correlated with the opening value of the current handle, and the pressure calibration value can be optimized and finally determined by combining different machine debugging.

And S7, acquiring the real-time rotating speed n of the hydraulic motor in the process of gradually reducing the rotating speed of the hydraulic motor, comparing the real-time rotating speed n with a steady stopping rotating speed calibration value n2 (n 2 is close to 0) of the hydraulic motor, and controlling the brake electromagnetic valve to lose electricity when the real-time rotating speed n is smaller than or equal to the rotating speed calibration value n2, so that the brake is braked steadily.

When the tractor in the prior art is operated, the positions and the speeds of the pulling handles of the tractor are different due to different operation habits, and some operators can slowly pull the handles slightly, so that the tractor can be slowly started; the handle can be pulled by someone and an operator rapidly and greatly, at the moment, the pressure of the traction machine fluctuates violently at the moment of starting, so that the starting impact of the traction machine can be caused, in addition, when the traction machine is stopped each time, the winding drum can bear a certain degree of load, when the traction operation is carried out again, if the hydraulic pump is not controlled, the hydraulic pump is likely to be started to have insufficient power, the winding drum is caused to slip, and even the situation of flameout caused by insufficient power exists, so that certain potential safety hazards exist.

With reference to fig. 2, after the control method of the present invention is modified, when the traction operation is started, the pressure of the hydraulic pump and the rotation speed of the hydraulic motor are adjusted at the same time:

On the one hand: when the handle is operated from the middle position to the traction position at any opening degree and at any pulling speed, a certain initial current value I1 is set to control the displacement of the hydraulic pump no matter how the handle is pulled, so that no matter how the handle is operated at any opening degree, the hydraulic pump pressure is controlled to be gradually increased by a current which is dynamically adjusted in real time, different hydraulic pump displacement can not be provided according to the opening degree of the handle pushed by an operator, the pressure value C of the hydraulic pump is collected in real time through a pressure sensor in the process of gradually increasing the pressure, compared with a pressure calibration value C2 in a nonvolatile memory, the calibration value C2 is calculated according to the load pressure value when the operation is stopped last time, the brake is controlled to be opened only when the pressure value C is larger than the pressure calibration value C2, the hydraulic system can provide enough power to resist the load when the operation is stopped last time, the hydraulic system can provide enough power no matter how the opening degree of the operation handle is opened, the load born on a winding drum can be smoothly started, the hydraulic system can provide enough power, the phenomenon of rolling phenomenon that the load is violent in starting moment is not caused, and the phenomenon of rolling of the winding drum is not caused by fluctuation of the load.

In the process that the rotating speed of the hydraulic motor is gradually increased, acquiring the real-time rotating speed n of the hydraulic motor through a rotating speed sensor, comparing the real-time rotating speed n with the calibrated motor stable working rotating speed n1 of the hydraulic motor, and when the real-time rotating speed n is larger than or equal to a rotating speed calibration value n1, completing a stable starting process by a traction system, wherein the control current of the hydraulic pump is stably and rapidly switched to a hydraulic pump control current I2 corresponding to the opening of a current handle from I1;

Specifically, in order to ensure that the opening of the handle can be matched with the speed of the hydraulic motor, in the process of gradually increasing the rotating speed of the hydraulic motor, the real-time rotating speed N of the hydraulic motor is obtained, the real-time rotating speed N is compared with a rotating speed calibration value N1 of the hydraulic motor, the rotating speed calibration value N1 is set according to the actual requirement of the tractor, when the real-time rotating speed N is larger than the rotating speed calibration value N1, the traction speed required by the tractor can be completed, the output current value is dynamically regulated to control the displacement of the hydraulic pump, the rotating speed of the hydraulic motor is consistent with the traction speed target value N, and in the process of using the tractor subsequently, the actual traction speed can be regulated according to the opening of the handle.

On the other hand, when the constant-speed traction operation is continued, after the handle is pulled away from the neutral position, a target traction speed V1 is proportionally calculated from the current handle opening as a target value, an actual rotation speed measured from the rotation speed sensor is proportionally calculated to obtain a current traction speed V as a feedback value, and a deviation of V1 and V is calculated, wherein: the handle opening and the target traction speed V1 can be obtained by referring to a comparison table, the actual rotation speed and the current traction speed V have a fixed proportion calculation relationship, and the hydraulic pump control current I2 is dynamically regulated by adopting PID regulation or other feasible closed-loop control modes, so that the deviation of V1 and V approaches 0.

In this embodiment, the reference current I2 is calculated according to parameters such as the handle opening (the target traction speed V1 can be correspondingly obtained), the real-time pressure C of the hydraulic pump, the engine speed E, the equipment transmission ratio, etc., and the calculation process is divided into the following steps:

(1) Determining an accelerator rotating speed value E1 of an engine according to real-time pressure C of a hydraulic pump, wherein the value of E1 and C are in a direct proportional relation, namely E1=K1×C, and a proportionality constant K1 is related to an actual power output power curve of the engine;

(2) As the handle opening increases, the engine speed E varies between E1 and Emax, emax being the highest speed of the engine;

(3) Reference current i2=k2× (V1/E) at a certain handle opening, and proportionality constant K2 is related to parameters such as maximum displacement of the main pump, proportional relation between actual displacement of the main pump and current, motor displacement, equipment transmission ratio, and the like.

And on the basis of the reference current I2, the target traction speed V1 is compared with the actual traction speed V fed back by a speed sensor in real time by adopting a PID (proportion integration differentiation) regulation or other feasible closed-loop control modes, the hydraulic pump control current I2 is dynamically regulated, so that the deviation between V1 and V approaches to 0, the traction speed is completely consistent with the speed V1 corresponding to the opening degree of the handle, and the traction machine can maintain the speed to be the target value V1 for constant-speed operation.

In the present embodiment, the process of controlling the rotation speed of the hydraulic motor by the engine is: when the traction operation is started, after the handle is started at any opening, the throttle rotating speed value E1 is the same as the method, and because the brake is not started at the moment, the real-time pressure C of the hydraulic pump is replaced by the pressure calibration value C2 in the nonvolatile memory during calculation, namely E1=K1×C2, the throttle rotating speed value E1 is sent to the engine controller, after the brake is opened, the storage value C2 in the nonvolatile memory is replaced by the real-time pressure C of the hydraulic pump, the engine rotating speed is positively related to the opening proportion of the handle, and the engine rotating speed proportion is increased and matched with the rotating speed of the winding drum along with the gradual increase of the pulling angle of the handle.

Referring to fig. 3, the present invention discloses two processes of stopping the traction operation, one is a process of normally stopping the traction operation, i.e., actively stopping the traction operation, and the other is a process of abnormally stopping the traction operation, i.e., passively stopping the traction operation.

Specifically, when the traction operation is actively stopped, the operating handle returns to the neutral position from any opening, the current pressure value measured by the pressure sensor at the moment is written into the nonvolatile memory of the controller and recorded as a stored value C1, the stored value C1 represents the corresponding current load value before braking, and the pressure calibration value C2 in the nonvolatile memory at the next starting time is calculated according to the stored value C1, wherein: c2 The value of the delta C is related to the response time of the hydraulic system, the calibration setting can be carried out through an equipment setting test, and the overshoot phenomenon can be effectively avoided by reasonably setting the delta C; meanwhile, the control current of the hydraulic pump becomes 0, the hydraulic pump stops outputting, the pressure gradually decreases, and the speed of the hydraulic motor gradually decreases;

In the process that the rotating speed of the hydraulic motor is gradually reduced, the rotating speed measured by the rotating speed sensor is used for judging, the real-time rotating speed of the hydraulic motor is obtained, and compared with the rotating speed calibration value n2 of the hydraulic motor, when the real-time rotating speed is smaller than the rotating speed calibration value n2, the brake is controlled to brake, so that the operation handle can be operated from the middle position to the traction position at any opening degree and at any pulling speed, the safe stopping operation without impact can be realized completely, and the pressure impact caused by too fast brake and the brake damage or the rollback condition caused by too slow brake are avoided.

When the traction stopping operation is executed, after the handle is reset, an engine throttle rotation speed value E1 is calculated and controlled according to a pressure calibration value C2 in the nonvolatile memory, the throttle rotation speed value E1 is sent to the engine controller, the engine is reduced to a rotation speed matched with the pressure calibration value C2 in the nonvolatile memory, and after the brake is braked, the engine rotation speed is reduced to a standby rotation speed.

Another is an abnormal stop traction operation, in particular, when a constant speed traction operation is continued, if an unexpected situation occurs, for example: the traction force is suddenly increased due to abnormal operation states such as unexpected clamping of the materials to be towed, and the traction operation is passively stopped in order to ensure the construction safety.

After the traction operation is passively stopped, the handle needs to be restored to the middle position from the angle of the handle before the protection state is triggered, at the moment, the processor receives a signal that the handle returns to the middle position, the equipment jumps out of the protection state, and the equipment returns to normal.

Specifically, in this embodiment, the handle is used as an input of a traction operation control signal, and provides an input of a voltage proportion signal and two direction signals, wherein the direction signals are switching value signals for controlling operation, stopping and operation directions, and the voltage proportion signal is adjusted according to the change of the opening of the handle.

In the embodiment, the opening and closing of the brake are controlled by the electromagnetic valve; the traction preset potentiometer is arranged for setting the maximum traction of the equipment.

Example 2

On the basis of the above embodiment 1, in order to implement the method of the above embodiment 1, the present invention further provides a control system of a hydraulic tractor, including:

A controller capable of executing the above control method;

the hydraulic pump is an electric proportional variable pump, a bidirectional proportional electromagnetic valve is integrated with the hydraulic pump, and the opening of the electromagnetic valve is regulated through proportional current input to realize the displacement regulation of the hydraulic pump;

the hydraulic motor is connected with the winding drum through a speed reducer and a gear pair and drives the winding drum to rotate;

the engine is connected with the hydraulic pump, and is used for converting the work of the hydraulic pump into the pressure energy of the hydraulic system by driving the hydraulic pump to rotate so as to provide energy supply for the hydraulic system;

the brake is used for transferring the external load on the winding drum to a mechanical structural part of the equipment, a control oil port is arranged on the brake, when the control oil port is communicated with the pressure oil loop, an internal piston overcomes the pressing force of a spring and acts, the friction resistance of a brake pad disappears, and the brake is in an open state and no braking torque is generated any more; when the control oil port and the pressure oil loop are disconnected, the piston is reset under the action of spring force, the brake pad generates enough friction resistance, the brake is in a braking state, and the hydraulic system is in a low-pressure standby state;

The electromagnetic valve is a two-position three-way electromagnetic reversing valve and is used for controlling the on-off of a pressure oil way of the brake so as to control the brake to be opened and closed, and after the brake is opened, the external load on the winding drum is born and driven by a hydraulic motor, so that the traction or wire feeding operation of the tractor is realized;

the pressure sensor is arranged at a working oil port of the hydraulic pump and is used for measuring the real-time working pressure of the hydraulic system;

The rotating speed sensor is arranged on the hydraulic motor and is connected with the controller through a cable and is used for measuring the real-time rotating speed of the motor;

The handle is used as an input element of a traction operation control signal, is connected with the controller through a cable, provides input of a voltage proportion signal and two direction signals, and the direction signals are switching value signals and are used for controlling operation, stopping and operation directions;

The throttle potentiometer is connected with the controller through a cable and is used for setting the rotating speed of the engine;

and the traction preset potentiometer is connected with the controller through a cable and is used for setting the maximum traction of the equipment.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims (10)

1. A method of controlling a hydraulic traction machine, comprising the steps of:

starting traction operation:

S1, operating a handle from a middle position to a traction position at any opening degree and at any pulling speed, controlling the displacement of a hydraulic pump by using a variable current value I1, gradually increasing the variable current value I1 in a calibrated time-dependent incremental mode, gradually increasing the working pressure of the hydraulic pump at the moment, and starting a pre-pressurizing process;

S2, acquiring a real-time pressure value C of the hydraulic pump in the process of gradually increasing the pressure of the hydraulic pump, comparing the pressure value C with a pressure calibration value C2 in a nonvolatile memory, and controlling a brake electromagnetic valve to be electrified when the pressure value C is greater than or equal to the pressure calibration value C2, opening a brake, and starting the hydraulic motor to rotate and gradually accelerate;

S3, acquiring a real-time rotating speed n of the hydraulic motor in the process of gradually increasing the rotating speed of the hydraulic motor, comparing the real-time rotating speed n with a calibrated motor stable working rotating speed n1 of the hydraulic motor, and when the real-time rotating speed n is larger than or equal to a rotating speed calibration value n1, completing a stable starting process by a traction system, wherein the control current of the hydraulic pump is switched from a variable current value I1 to a hydraulic pump control current I2 corresponding to the opening of a current handle;

Continuous constant speed traction operation:

S4, proportionally calculating a target traction speed V1 from the opening of a current handle as a target value, proportionally calculating the actual rotation speed measured by a rotation speed sensor to obtain the current traction speed V as a feedback value, calculating the deviation of V1 and V, dynamically adjusting a hydraulic pump control current I2 by adopting a PID (proportion integration differentiation) regulation closed-loop control mode to enable the deviation of V1 and V to approach 0, wherein the tractor is in a constant-speed traction state, and repeating the above processes when an operator changes the opening of a control handle, and re-realizing constant-speed traction operation according to the changed opening of the handle;

stopping the traction operation:

s5, operating the handle to return to the middle position at any opening degree and at any pulling speed, and recovering the control current of the hydraulic pump to 0, wherein the hydraulic pump stops outputting hydraulic oil at the moment, the rotating speed of the hydraulic motor is gradually reduced, and the speed of the reduction is related to the load of the current winding drum;

S6, when the handle closing switch is triggered, acquiring a real-time pressure value C of the hydraulic pump, writing the pressure value C into a nonvolatile memory to obtain a stored value C1, and calculating according to the stored value C1 to obtain a pressure calibration value C2 in the nonvolatile memory when the hydraulic pump is started next time;

And S7, acquiring the real-time rotating speed n of the hydraulic motor in the process of gradually reducing the rotating speed of the hydraulic motor, comparing the real-time rotating speed n with a steady stopping rotating speed calibration value n2 of the hydraulic motor, and controlling the brake electromagnetic valve to lose electricity when the real-time rotating speed n is smaller than or equal to the rotating speed calibration value n2, so that the brake is braked steadily.

2. The control method of a hydraulic traction machine according to claim 1, characterized in that: when the traction operation is started, after the handle is started at any opening, an engine throttle rotation speed value E1 is calculated and controlled according to a pressure calibration value C2 in a nonvolatile memory, the throttle rotation speed value E1 is sent to an engine controller through a CAN bus, so that the engine provides a rotation speed matched with the pressure calibration value C2 in the nonvolatile memory, after a brake is opened, the engine rotation speed is positively related to the opening proportion of the handle, and the rotation speed of a winding drum is matched and adjusted along with the gradual increase of the pulling angle of the handle and the increase of the engine rotation speed proportion.

3. The control method of a hydraulic traction machine according to claim 1, characterized in that: when the traction stopping operation is executed, after the handle is reset, a throttle rotating speed value E1 of the engine is calculated according to a recalculated pressure calibration value C2 in the nonvolatile memory, the throttle rotating speed value E1 is sent to the engine controller through the CAN bus, the engine is reduced to a rotating speed matched with the pressure calibration value C2 in the nonvolatile memory, after the brake is braked, the engine rotating speed is reduced to a standby rotating speed, and the standby rotating speed is regulated through the throttle potentiometer.

4. The control method of a hydraulic traction machine according to claim 1, characterized in that: in step S1, the handle is used as an input of a traction operation control signal, and one voltage proportion signal and two direction signals are provided as inputs of a switching value signal, wherein the direction signals are used for controlling operation, stopping and operation directions, and the voltage proportion signal is adjusted according to the change of the opening degree of the handle.

5. The control method of a hydraulic traction machine according to claim 1, characterized in that: in step S2 and step S6, a pressure sensor is used to obtain a real-time pressure value C of the hydraulic system.

6. The control method of a hydraulic traction machine according to claim 1, characterized in that: in step S3 and step S7, the real-time rotational speed n of the hydraulic motor is acquired using a rotational speed sensor.

7. The control method of a hydraulic traction machine according to claim 1, characterized in that: in step S3, the process of dynamically adjusting the output current value is: PWM current reference value I2 is calculated according to parameters of handle opening, engine rotating speed and equipment transmission ratio, and meanwhile, the difference between target traction speed V1 and actual traction speed V is used as a target value and a feedback value of PID regulation, and hydraulic pump control current I2 is dynamically regulated to enable deviation of V1 and V to approach 0.

8. The control method of a hydraulic traction machine according to claim 1, characterized in that: the on-off of an oil way in the brake is controlled through an electromagnetic valve, the electromagnetic valve is electrified, the oil way is conducted, the brake is opened, and the winding drum can rotate; the electromagnetic valve is powered off, the oil way is closed, the brake is combined, and the winding drum cannot rotate.

9. The control method of a hydraulic traction machine according to claim 1, characterized in that: when constant-speed traction operation is executed, a traction preset value is set through a traction preset potentiometer, and a corresponding pressure value C3 is calculated according to the preset value; in the traction process, if the traction force suddenly decreases, the traction machine continues to run at a target traction speed V1 calculated by the opening degree of the handle; if the traction force suddenly increases, when the real-time pressure value C measured by the pressure sensor is greater than the preset pressure value C3, steps S5 to S7 are performed.

10. A control system for a hydraulic traction machine capable of implementing the control method according to any one of the preceding claims 1 to 9, characterized in that: comprising the following steps:

A controller capable of executing the above control method;

The hydraulic pump is an electric proportional variable pump, is integrated with a bidirectional proportional electromagnetic valve, and can control the opening of the electromagnetic valve through proportional current input to realize different displacement adjustment of the hydraulic pump;

the hydraulic motor is connected with the winding drum through a speed reducer and a gear pair and drives the winding drum to rotate;

the engine is connected with the hydraulic pump, and is used for converting the work of the hydraulic pump into the pressure energy of the hydraulic system by driving the hydraulic pump to rotate so as to provide energy supply for the hydraulic system;

The brake is used for transferring the external load on the winding drum to a mechanical structural part of the equipment, and when the brake brakes reliably, the hydraulic pump is in a low-pressure standby state;

The electromagnetic valve is a two-position three-way electromagnetic reversing valve and is used for controlling the on-off of an oil path of a brake so as to control the opening and the closing of the brake, and after the brake is opened, the external load on the winding drum is born and driven by a hydraulic motor to realize the traction or wire feeding operation of the tractor;

the pressure sensor is arranged at a working oil port of the hydraulic pump and is used for measuring the real-time pressure of the hydraulic pump, and the pressure measured by the pressure sensor is positively correlated with the external load born by the winding drum at present;

The rotating speed sensor is arranged on the hydraulic motor and is connected with the controller through a cable and is used for measuring the real-time rotating speed of the hydraulic motor;

The handle is used as an input element of a traction operation control signal, is connected with the controller through a cable, provides input of a voltage proportion signal and two direction signals, and the direction signals are switching value signals and are used for controlling operation, stopping and operation directions;

The throttle potentiometer is connected with the controller through a cable and is used for setting the rotating speed of the engine;

and the traction preset potentiometer is connected with the controller through a cable and is used for setting the maximum traction of the equipment.