A forklift gearbox assembly and hydraulic shift control system based on electromagnetic proportional valve

Abstract

This invention discloses a forklift gearbox assembly and hydraulic shift control system based on an electromagnetic proportional valve, comprising: a micro-motion-reverse gear lookup module, a micro-motion-forward gear lookup module, a micro-motion pedal angle lookup module, a first selection switch, a second selection switch, and a third selection switch; the gearbox oil pan temperature input interface is connected to the input ports of the micro-motion-reverse gear lookup module and the micro-motion-forward gear lookup module; the micro-motion pedal input interface is connected to the input terminal of the micro-motion pedal angle lookup module, and the output terminal of the micro-motion pedal angle lookup module is connected to the micro-motion-reverse gear lookup module and the micro-motion-forward gear lookup module, respectively. The module's input port is connected; the reverse gear input interface and the output of the micro-switch-reverse gear lookup module are connected to the input of the first selector switch; the forward gear input interface and the output of the micro-switch-forward gear lookup module are connected to the input of the second selector switch; the output of the second selector switch is connected to the input of the first selector switch; and the output of the first selector switch is connected to the input of the third selector switch. The output of the third selector switch outputs the electromagnetic proportional valve control current value. This invention makes the gear engagement, reversing, and micro-switch function more precise and smooth, reducing shift shock.

Description

Technical Field

[0001] This invention relates to the field of hydraulic shifting system technology, specifically to a forklift gearbox assembly and hydraulic shifting control system based on an electromagnetic proportional valve. Background Technology

[0002] The operating scenarios dictate that forklifts require frequent gear shifting and reversing operations during actual work. In certain situations, micro-motion functions are also frequently needed. Traditional hydraulic transmission forklifts typically use mechanical switching valves or multi-position solenoid valves to achieve gear shifting and reversing, and additional micro-motion valves are required to realize the micro-motion function. Due to their inherent characteristics, traditional mechanical structures or solenoid valves inevitably generate shifting shocks during gear engagement or reversal. Furthermore, the driver's experience can influence the transmission clutch, causing additional impact wear and affecting vehicle performance, reliability, and lifespan.

[0003] In the prior art, such as the invention patent with patent publication number CN117869488A, a clutch control device and clutch control method are disclosed. In this patent, the shift control valve is a solenoid valve. The shift control valve replaces the traditional pilot-operated switching solenoid valve. It can directly adjust the oil pressure in the control oil chamber of the clutch by adjusting the current of the shift control valve, so as to reduce shift shock and improve shift response speed. However, it cannot accurately control the micro-motion function. Summary of the Invention

[0004] The technical problem to be solved by this invention is to achieve precise hydraulic control of the micro-motion function of forklifts.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A control system for a forklift gearbox assembly based on an electromagnetic proportional valve includes: a micro-motion reverse gear lookup module 10, a micro-motion forward gear lookup module 20, a micro-motion pedal angle lookup module 30, a first selection switch 41, a second selection switch 42, and a third selection switch 43.

[0007] Among them, the transmission oil pan temperature input interface 51 is connected to the input ports of the micro-reverse gear lookup table module 10 and the micro-forward gear lookup table module 20;

[0008] The micro pedal input interface 52 is connected to the input end of the micro pedal angle lookup table module 30, and the output end of the micro pedal angle lookup table module 30 is connected to the input ports of the micro pedal reverse gear lookup table module 10 and the micro pedal forward gear lookup table module 20, respectively.

[0009] The output of the reverse gear input interface 53 and the micro-motion-reverse gear lookup table module 10 are connected to the input of the first selection switch 41;

[0010] The forward gear input interface 54 and the output terminal of the micro-motion-forward gear lookup module 20 are connected to the input terminal of the second selection switch 42;

[0011] The output terminal of the second selector switch 42 is connected to the input terminal of the first selector switch 41; and the output terminal of the first selector switch 41 is connected to the input terminal of the third selector switch 43, the output terminal of the third selector switch 43 outputs the electromagnetic proportional valve control current value.

[0012] In one embodiment of the present invention, the micro-pedal angle lookup module 30 is associated with an angle and voltage curve table compiled based on the characteristics of the angle sensor, and outputs the pedal opening corresponding to the oil pressure.

[0013] In one embodiment of the present invention, the micro-motion-reverse gear lookup module 10 includes a first first-order lookup module 11 and a first second-order lookup module 12;

[0014] The output of the micro pedal angle lookup module 30 is connected to the input of the first-order lookup module 11; the gearbox oil pan temperature input interface 51 and the output of the first-order lookup module 11 are connected to the input of the first-order lookup module 12, and the output of the first-order lookup module 12 is connected to the input of the first selection switch 41.

[0015] The first-order lookup module 11 is associated with the curve of the micro pedal opening voltage and the hydraulic system oil pressure compiled based on the experiment, and outputs the system oil pressure corresponding to the reverse gear position.

[0016] The first and second order lookup table module 12 is associated with the curves corresponding to oil temperature, oil pressure and output current, compiled based on experiments and the characteristics of the electromagnetic proportional valve, and outputs the control current of the electromagnetic proportional valve corresponding to the reverse gear position.

[0017] In one embodiment of the present invention, the micro-motion forward gear lookup module 20 includes a second first-order lookup module 21 and a second second-order lookup module 22;

[0018] The output of the micro pedal angle lookup module 30 is connected to the input of the second first-order lookup module 21; the gearbox oil pan temperature input interface 51 and the output of the second first-order lookup module 21 are connected to the input of the second second-order lookup module 22, and the output of the second second-order lookup module 22 is connected to the input of the second selection switch 42.

[0019] The second-order lookup module 21 is associated with the curve of the micro pedal opening voltage and the hydraulic system oil pressure compiled based on the experiment, and outputs the system oil pressure corresponding to the forward gear.

[0020] The second-order lookup table module 22 is associated with the curves corresponding to oil temperature, oil pressure and output current, compiled based on experiments and the characteristics of the electromagnetic proportional valve, and outputs the forward gear corresponding to the electromagnetic proportional valve control current.

[0021] In one embodiment of the present invention, the control system of the forklift gearbox assembly further includes a calibration and overshoot mode current loop module 61 and a calibration and overshoot mode input module 62; and the calibration and overshoot mode current loop module 61 and the calibration and overshoot mode input module 62 are connected to the input terminal of the third selection switch 43.

[0022] In one embodiment of the present invention, the control logic route for the reversing micro-motion condition is as follows:

[0023] The angle sensor connected to the micro pedal converts the driver's needs into an electrical signal; the micro pedal angle lookup module 30 finds the voltage value corresponding to the micro pedal opening degree, and then the first-order lookup module 11 finds the system oil pressure value corresponding to the reverse gear at the corresponding micro pedal opening degree; the temperature sensor collects the real-time oil pan temperature value and combines it with the system oil pressure value output by the first-order lookup module 11, and the first-second-order lookup module 12 finds the electromagnetic proportional valve control current value corresponding to the reverse gear.

[0024] At this time, the reverse gear signal corresponding to the first selection switch 41 is set to "1", the forward gear signal corresponding to the second selection switch 42 is set to "0", and the calibration and overshoot mode corresponding to the third selection switch 43 is set to "0". After the second selection switch 42 judges, the logic flow goes down path; after the first selection switch 41 judges, the logic flow goes up path; after the third selection switch 43 judges, the logic flow goes down path.

[0025] In one embodiment of the present invention, the forward micro-motion control logic route is as follows:

[0026] The angle sensor connected to the micro pedal converts the driver's needs into an electrical signal; the micro pedal angle lookup module 30 finds the voltage value corresponding to the micro pedal opening degree, and then the second first-order lookup module 21 finds the system oil pressure value corresponding to the forward gear at the corresponding micro pedal opening degree; the temperature sensor collects the real-time oil pan temperature value and combines it with the system oil pressure value output by the second first-order lookup module 21, and then the second second-order lookup module 22 finds the electromagnetic proportional valve control current value corresponding to the forward gear.

[0027] At this time, the forward gear signal corresponding to the second selection switch 42 is set to "1", the reverse gear signal corresponding to the first selection switch 41 is set to "0", and the calibration and overshoot mode corresponding to the third selection switch 43 is set to "0". After the second selection switch 42 determines, the logic flow goes up path; after the first selection switch 41 determines, the logic flow goes down path; and after the third selection switch 43 determines, the logic flow goes down path.

[0028] In one embodiment of the present invention, the calibration and overshoot mode control logic route is as follows:

[0029] At this time, the calibration and overshoot mode is entered. The reverse signal corresponding to the first selection switch 41 is set to "0", the forward signal corresponding to the second selection switch 42 is set to "0", the calibration and overshoot mode input module 62 is set to "1", the logic flow is driven by the first selection switch 41, the logic flow is driven by the second selection switch 42, and the logic flow is driven by the third selection switch 43.

[0030] The calibration and overshoot mode input module 62 outputs calibration and overshoot current according to the current curve preset in the calibration and overshoot mode current loop module 61, and outputs it through the third selection switch 43. At this time, the electromagnetic proportional valve works according to the current curve preset in the calibration and overshoot mode current loop module 61.

[0031] A forklift hydraulic shift control system, which applies the control system of the forklift gearbox assembly based on the electromagnetic proportional valve described above, includes: an oil reservoir 1, a filter 2, an oil supply pump 3, an electromagnetic proportional valve 4, a forward gear clutch 5, a reverse gear clutch 6, and a main pressure regulating valve 7.

[0032] The control system of the forklift gearbox assembly based on the electromagnetic proportional valve is communicatively connected to the electromagnetic proportional valve 4.

[0033] The oil in the oil tank 1 is filtered by the filter 2, and then the transmission oil is pressurized by the oil supply pump 3 and divided into two paths at the outlet; after being pressured by the main pressure regulating valve 7, it is input into the oil inlet passage at the bottom of the electromagnetic proportional valve 4.

[0034] The control system of the forklift gearbox assembly based on the electromagnetic proportional valve precisely controls the movement of the electromagnetic proportional valve 4 by outputting the current, thereby controlling the oil pressure of the forward gear clutch 5 and the reverse gear clutch 6 to realize the functions of each gear and micro-motion.

[0035] In one embodiment of the present invention, in neutral, the electromagnetic proportional valve 4 does not work, the valve core of the electromagnetic proportional valve 4 is in the neutral position, and there is no oil pressure on both the forward and reverse clutches, so they are not engaged.

[0036] In forward gear, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the gear position signal, increases the current of the electromagnetic coil at the S1 end of the electromagnetic proportional valve 4 proportionally, the valve core moves to the S1 end, the main oil circuit is connected to the forward gear clutch chamber, the oil pressure is established proportionally, the forward gear clutch 5 engages, and the forward gear power transmission is realized.

[0037] If the micro pedal is pressed at this time, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the electrical signal converted from the opening of the micro pedal, releases the current of the electromagnetic coil at the S1 end proportionally, the valve core moves to the neutral position, reduces or cuts off the oil circuit between the main oil circuit and the forward gear clutch chamber, the forward gear clutch chamber is depressurized, and the micro function in the forward gear mode is realized. If the micro pedal is released at this time, the forward gear is restored.

[0038] In reverse gear, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the gear signal, increases the current of the electromagnetic coil at the S2 end of the electromagnetic proportional valve 4 proportionally, the valve core moves to the S2 end, the main oil circuit is connected to the reverse gear clutch chamber, the oil pressure is established proportionally, the reverse gear clutch engages, and the reverse gear power transmission is realized.

[0039] If the micro pedal is pressed at this time, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the electrical signal converted from the opening of the micro pedal, releases the current of the electromagnetic coil at the S2 end proportionally, the valve core moves to the neutral position, reduces or cuts off the oil circuit between the main oil circuit and the reverse gear clutch chamber, the reverse gear clutch chamber is depressurized, and the micro function in reverse gear mode is realized. If the micro pedal is released at this time, reverse gear is restored.

[0040] Compared with the prior art, the beneficial effects of the present invention are: addressing the shortcomings of the existing hydraulic transmission shifting system for small-tonnage forklifts, a three-position four-way electromagnetic proportional valve is used to replace the traditional micro-motion valve, buffer valve, and gear position valve to realize the functions of shifting and micro-motion, and a proportional valve control unit is used to control the electromagnetic valve to achieve more precise hydraulic control.

[0041] This invention replaces the gear-positioning pressure valve, buffer valve, reversing solenoid valve, and micro valve in the traditional structure with an electromagnetic proportional valve, which greatly reduces the number of hardware components, making the entire system structure more streamlined and compact in size, and facilitating vehicle layout.

[0042] This invention uses an electromagnetic proportional valve to make gear engagement, reversing, and micro-motion functions more precise and smooth, reducing shift shock, minimizing friction plate wear and the risk of potential friction plate burning, extending the service life of components, reducing overall vehicle economic losses and operational risks, and improving overall vehicle operability and comfort.

[0043] The control system of the forklift gearbox assembly based on electromagnetic proportional valve has various connection and communication modes with the vehicle, which can be adapted to different vehicle configurations. It has strong versatility, and the addition of the control module enables the vehicle to achieve a higher level of intelligent control, which greatly improves the informatization and intelligence of the vehicle.

[0044] The invention allows for the calibration of the proportional valve pressure adjustment curve and the micro-motion pedal opening for different working conditions and usage scenarios, enabling the vehicle to achieve efficient and comfortable operation under various working conditions and scenarios. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of a control system for a forklift gearbox assembly based on an electromagnetic proportional valve, according to an embodiment of the present invention.

[0046] Figure 2 This is a schematic diagram of the control logic for the reversing micro-motion operation in an embodiment of the present invention.

[0047] Figure 3 This is a circuit diagram of the calibration and overshoot mode control logic in an embodiment of the present invention.

[0048] Figure 4 This is a diagram of a forklift hydraulic shifting control system according to an embodiment of the present invention. Detailed Implementation

[0049] To facilitate understanding of the technical solution of the present invention by those skilled in the art, the technical solution of the present invention will now be further described in conjunction with the accompanying drawings.

[0050] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0051] Please see Figures 1 to 3 As shown, the present invention provides a control system for a forklift gearbox assembly based on an electromagnetic proportional valve, comprising: a micro-motion reverse gear lookup table module 10, a micro-motion forward gear lookup table module 20, a micro-motion pedal angle lookup table module 30, a first selection switch 41, a second selection switch 42, and a third selection switch 43.

[0052] In this embodiment, the transmission oil pan temperature input interface 51 is connected to the input ports of the micro-reverse gear lookup module 10 and the micro-forward gear lookup module 20. The micro pedal input interface 52 is connected to the input terminal of the micro pedal angle lookup module 30, and the output terminal of the micro pedal angle lookup module 30 is connected to the input ports of the micro-reverse gear lookup module 10 and the micro-forward gear lookup module 20, respectively. The reverse gear input interface 53 and the output terminal of the micro-reverse gear lookup module 10 are connected to the input terminal of the first selector switch 41. The forward gear input interface 54 and the output terminal of the micro-forward gear lookup module 20 are connected to the input terminal of the second selector switch 42. The output terminal of the second selector switch 42 is connected to the input terminal of the first selector switch 41; and the output terminal of the first selector switch 41 is connected to the input terminal of the third selector switch 43, the output terminal of the third selector switch 43 outputs the electromagnetic proportional valve control current value.

[0053] In this embodiment, the first selection switch 41 has a "0" position and a "1" position, where a "0" position indicates the lower path and a "1" position indicates the upper path. That is, the reverse gear goes up when a signal is received, and the lower path goes down when no signal is received. The second selection switch 42 has a "0" position and a "1" position, where a "0" position indicates the lower path and a "1" position indicates the upper path. That is, the forward gear goes up when a signal is received, and the lower path goes down when no signal is received. And the third selection switch 43 has a "0" position and a "1" position, where a "0" position indicates the lower path and a "1" position indicates the upper path. That is, the calibration and overshoot mode signals go up when received, and the lower path goes down when no signal is received.

[0054] In one embodiment of the present invention, the micro-pedal angle lookup module 30 is associated with an angle and voltage curve table compiled based on the characteristics of the angle sensor, and outputs the pedal opening corresponding to the oil pressure.

[0055] In one embodiment of the present invention, the micro-motion reverse gear lookup module 10 includes a first-order lookup module 11 and a first-second-order lookup module 12. The output terminal of the micro-motion pedal angle lookup module 30 is connected to the input terminal of the first-order lookup module 11. The transmission oil pan temperature input interface 51, the output terminal of the first-order lookup module 11, and the input terminal of the first-second-order lookup module 12 are connected. The output terminal of the first-second-order lookup module 12 is connected to the input terminal of the first selection switch 41. The first-order lookup module 11 is associated with a curve corresponding to the micro-motion pedal opening voltage and the hydraulic system oil pressure, compiled based on experiments, and outputs the reverse gear position corresponding to the system oil pressure. The first-second-order lookup module 12 is associated with a curve corresponding to the oil temperature, oil pressure, and output current, compiled based on experiments and the characteristics of the electromagnetic proportional valve, and outputs the reverse gear position corresponding to the electromagnetic proportional valve control current.

[0056] In one embodiment of the present invention, the micro-motion forward gear lookup module 20 includes a second first-order lookup module 21 and a second second-order lookup module 22. The output terminal of the micro-motion pedal angle lookup module 30 is connected to the input terminal of the second first-order lookup module 21. The transmission oil pan temperature input interface 51, the output terminal of the second first-order lookup module 21, and the input terminal of the second second-order lookup module 22 are connected, and the output terminal of the second second-order lookup module 22 is connected to the input terminal of the second selection switch 42. The second first-order lookup module 21 is associated with a curve corresponding to the micro-motion pedal opening voltage and the hydraulic system oil pressure, compiled based on experiments, and outputs the forward gear corresponding to the system oil pressure. The second second-order lookup module 22 is associated with a curve corresponding to the oil temperature, oil pressure, and output current, compiled based on experiments and the characteristics of the electromagnetic proportional valve, and outputs the forward gear corresponding to the electromagnetic proportional valve control current.

[0057] In one embodiment of the present invention, the control system of the forklift gearbox assembly further includes a calibration and overshoot mode current loop module 61 and a calibration and overshoot mode input module 62. The calibration and overshoot mode current loop module 61 and the calibration and overshoot mode input module 62 are connected to the input terminal of the third selection switch 43.

[0058] In one embodiment of the present invention, the control system of the forklift gearbox assembly further includes a current filtering module 70 and an electromagnetic proportional valve current output interface 55. The input terminal of the current filtering module 70 is connected to the output terminal of the third selector switch 43 to prevent current fluctuations from affecting the system. The current filtered by the current filtering module 70 passes through the electromagnetic proportional valve current output interface 55 to control the opening degree of the electromagnetic proportional valve in the forklift hydraulic shift control system.

[0059] In one embodiment of the present invention, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve can be connected to the relevant systems of the vehicle via a CAN line or a hard wire. The received gear position signal is converted into a current signal of the electromagnetic proportional valve to realize gear position control, and the received micro pedal opening is converted into a current signal of the electromagnetic proportional valve to realize micro control.

[0060] In one embodiment of the present invention, such as Figure 1 As shown, the control logic route for the forward micro-motion condition is as follows:

[0061] The angle sensor connected to the micro pedal converts the driver's input into an electrical signal. The micro pedal angle lookup module 30 finds the voltage value corresponding to the micro pedal opening degree, and then the second-order lookup module 21 finds the system oil pressure value corresponding to the forward gear at that micro pedal opening degree. The temperature sensor collects the real-time oil pan temperature value and combines it with the system oil pressure value output from the second-order lookup module 21. The second-order lookup module 22 then finds the electromagnetic proportional valve control current value corresponding to the forward gear.

[0062] At this time, the forward signal corresponding to the second selection switch 42 is set to "1", the reverse signal corresponding to the first selection switch 41 is set to "0", and the calibration and overshoot mode corresponding to the third selection switch 43 is set to "0". Based on the judgment of the second selection switch 42, the logic flow proceeds to the up path; based on the judgment of the first selection switch 41, the logic flow proceeds to the down path; based on the judgment of the third selection switch 43, the logic flow proceeds to the down path. At this time, the logic operation is as follows: Figure 1 As shown, the solenoid valve operating current corresponding to the forward gear output by the second-order lookup table module 22 is input to the current filtering module 70 via the second selection switch 42, the first selection switch 41, and the third selection switch 43. After filtering, it is output to the solenoid proportional valve through the solenoid proportional valve current output interface 55. Figures 1 to 3 The dashed line in the middle represents the data flow.

[0063] In one embodiment of the present invention, such as Figure 2 As shown, the control logic route for the reversing micro-motion condition is as follows:

[0064] The angle sensor connected to the micro pedal converts the driver's input into an electrical signal. The micro pedal angle lookup module 30 finds the voltage value corresponding to the micro pedal opening degree, and then the first-order lookup module 11 finds the system oil pressure value corresponding to the reverse gear position at the corresponding micro pedal opening degree. The temperature sensor collects the real-time oil pan temperature value and combines it with the system oil pressure value output from the first-order lookup module 11. The first-second-order lookup module 12 then finds the electromagnetic proportional valve control current value corresponding to the reverse gear position.

[0065] At this time, the reverse gear signal corresponding to the first selection switch 41 is set to "1", the forward gear signal corresponding to the second selection switch 42 is set to "0", and the calibration and overshoot mode corresponding to the third selection switch 43 is set to "0". Based on the judgment of the second selection switch 42, the logic flow proceeds to the lower path; based on the judgment of the first selection switch 41, the logic flow proceeds to the upper path; and based on the judgment of the third selection switch 43, the logic flow proceeds to the lower path. At this time, the logic operation is as follows: Figure 2 As shown, the solenoid valve operating current corresponding to the reverse gear output by the first and second order lookup table module 12 is input to the current filtering module 70 via the first selection switch 41 and the third selection switch 43. After filtering, it is output to the solenoid proportional valve through the solenoid proportional valve current output interface 55.

[0066] In one embodiment of the present invention, such as Figure 3As shown, the control logic route for calibration and overshoot mode is as follows: When entering calibration and overshoot mode, the reverse signal corresponding to the first selection switch 41 is set to "0", the forward signal corresponding to the second selection switch 42 is set to "0", the calibration and overshoot mode input module 62 is set to "1", the logic flow proceeds to the lower path after judgment by the first selection switch 41, the logic flow proceeds to the lower path after judgment by the second selection switch 42, and the logic flow proceeds to the upper path after judgment by the third selection switch 43.

[0067] The calibration and overshoot mode input module 62 outputs calibration and overshoot current according to the current curve preset in the calibration and overshoot mode current loop module 61, and outputs it through the third selection switch 43. At this time, the electromagnetic proportional valve works according to the current curve preset in the calibration and overshoot mode current loop module 61.

[0068] At this point, the logic operates as follows: Figure 3 As shown, the calibration and overshoot mode current loop module 61 outputs calibration and overshoot current according to the preset current curve. The third selection switch 43 inputs to the current filtering module 70. After filtering, the current is output to the electromagnetic proportional valve through the electromagnetic proportional valve current output interface 55. At this time, the electromagnetic proportional valve works according to the preset current curve. This mode is mainly used to debug the functions of the gearbox and clutch and to calibrate the clutch engagement point current during the testing phase.

[0069] Please see Figures 1 to 4 As shown, the present invention also provides a forklift hydraulic shifting control system, which applies the above-described control system for the forklift gearbox assembly based on an electromagnetic proportional valve, including: an oil reservoir 1, a filter 2, an oil supply pump 3, an electromagnetic proportional valve 4, a forward gear clutch 5, a reverse gear clutch 6, and a main pressure regulating valve 7.

[0070] In this embodiment, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve is communicatively connected to the electromagnetic proportional valve 4. The oil in the reservoir 1, after being filtered by the filter 2, is pressurized by the oil supply pump 3 and then divided into two paths at the outlet: one path enters the shifting oil circuit, and the other enters the acceleration oil circuit. The electromagnetic proportional valve 4, the forward clutch 5, and the reverse clutch 6 are located in the shifting oil circuit. After being pressurized by the main pressure regulating valve 7, the oil is input to the bottom inlet of the electromagnetic proportional valve 4. The control system of the forklift gearbox assembly based on the electromagnetic proportional valve precisely controls the movement of the electromagnetic proportional valve 4 through the output current, thereby controlling the oil pressure of the forward clutch 5 and the reverse clutch 6, realizing the functions of each gear and micro-motion.

[0071] In one embodiment of the present invention, in neutral, the electromagnetic proportional valve 4 is not working, the valve core of the electromagnetic proportional valve 4 is in the neutral position, and there is no oil pressure on both the forward and reverse clutches, so they are not engaged.

[0072] In one embodiment of the present invention, in forward gear, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the gear position signal, increases the current of the electromagnetic coil at the S1 end of the electromagnetic proportional valve 4 proportionally, the valve core moves to the S1 end, the main oil circuit is connected to the forward gear clutch chamber, the oil pressure is established proportionally, the forward gear clutch 5 engages, and the forward gear power transmission is realized.

[0073] If the micro pedal is pressed at this time, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the electrical signal converted from the opening of the micro pedal, releases the current of the electromagnetic coil at the S1 end proportionally, the valve core moves to the neutral position, reduces or cuts off the oil circuit between the main oil circuit and the forward gear clutch chamber, and the forward gear clutch chamber is depressurized, realizing the micro function in the forward gear mode. If the micro pedal is released at this time, the forward gear is restored.

[0074] In one embodiment of the present invention, in reverse gear, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the gear position signal, increases the current of the electromagnetic coil at the S2 end of the electromagnetic proportional valve 4 proportionally, the valve core moves to the S2 end, the main oil circuit is connected to the reverse gear clutch chamber, the oil pressure is established proportionally, the reverse gear clutch engages, and the reverse gear power transmission is realized.

[0075] If the micro pedal is pressed at this time, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the electrical signal converted from the opening of the micro pedal, releases the current of the electromagnetic coil at the S2 end proportionally, the valve core moves to the neutral position, reduces or cuts off the oil circuit between the main oil circuit and the reverse gear clutch chamber, the reverse gear clutch chamber is depressurized, and the micro function in reverse gear mode is realized. If the micro pedal is released at this time, reverse gear is restored.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0077] The above embodiments are merely examples of implementation methods of the invention. The scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A control system for a forklift gearbox assembly based on an electromagnetic proportional valve, characterized in that, include: Micro-reverse gear lookup table module (10), micro-forward gear lookup table module (20), micro-pedal angle lookup table module (30), first selection switch (41), second selection switch (42), third selection switch (43); Among them, the transmission oil pan temperature input interface (51) is connected to the input ports of the micro-reverse gear lookup table module (10) and the micro-forward gear lookup table module (20); The micro pedal input interface (52) is connected to the input end of the micro pedal angle lookup table module (30), and the output end of the micro pedal angle lookup table module (30) is connected to the input ports of the micro-reverse gear lookup table module (10) and the micro-forward gear lookup table module (20), respectively. The output of the reverse gear input interface (53) and the micro-motion-reverse gear lookup table module (10) are connected to the input of the first selection switch (41); The output of the forward gear input interface (54) and the micro-motion forward gear lookup module (20) are connected to the input of the second selection switch (42); The output terminal of the second selector switch (42) is connected to the input terminal of the first selector switch (41); and the output terminal of the first selector switch (41) is connected to the input terminal of the third selector switch (43), the output terminal of the third selector switch (43) outputs the electromagnetic proportional valve control current value.

2. The control system for the forklift gearbox assembly based on an electromagnetic proportional valve according to claim 1, characterized in that, The micro-pedal angle lookup module (30) is associated with an angle and voltage curve table compiled based on the characteristics of the angle sensor, and outputs the pedal opening corresponding to the oil pressure.

3. The control system for the forklift gearbox assembly based on an electromagnetic proportional valve according to claim 2, characterized in that, The micro-motion reverse gear lookup module (10) includes a first-order lookup module (11) and a first-second-order lookup module (12); The output of the micro pedal angle lookup module (30) is connected to the input of the first-order lookup module (11); the output of the gearbox oil pan temperature input interface (51) and the first-order lookup module (11) is connected to the input of the first-order lookup module (12), and the output of the first-order lookup module (12) is connected to the input of the first selection switch (41); The first-order lookup module (11) is associated with the curve of the micro pedal opening voltage and hydraulic system oil pressure compiled based on the experiment, and outputs the system oil pressure corresponding to the reverse gear. The first and second order lookup table module (12) is associated with the curves corresponding to oil temperature, oil pressure and output current compiled based on the test and the characteristics of the electromagnetic proportional valve, and outputs the reverse gear position corresponding to the electromagnetic proportional valve control current.

4. The control system for the forklift gearbox assembly based on an electromagnetic proportional valve according to claim 2, characterized in that, The micro-motion forward gear lookup module (20) includes a second first-order lookup module (21) and a second second-order lookup module (22); The output of the micro pedal angle lookup module (30) is connected to the input of the second first-order lookup module (21); the output of the gearbox oil pan temperature input interface (51) and the second first-order lookup module (21) is connected to the input of the second second-order lookup module (22), and the output of the second second-order lookup module (22) is connected to the input of the second selection switch (42); The second-order lookup module (21) is associated with the curve of the micro pedal opening voltage and hydraulic system oil pressure compiled based on the experiment, and outputs the system oil pressure corresponding to the forward gear. The second-order lookup table module (22) is associated with the curves corresponding to oil temperature, oil pressure and output current compiled based on experiments and the characteristics of electromagnetic proportional valves, and outputs the forward gear corresponding to the electromagnetic proportional valve control current.

5. The control system for the forklift gearbox assembly based on an electromagnetic proportional valve according to claim 1, characterized in that, The control system of the forklift gearbox assembly also includes a calibration and overshoot mode current loop module (61) and a calibration and overshoot mode input module (62); and the calibration and overshoot mode current loop module (61) and the calibration and overshoot mode input module (62) are connected to the input terminal of the third selection switch (43).

6. The control system for the forklift gearbox assembly based on an electromagnetic proportional valve according to claim 3, characterized in that, The control logic route for the reversing micro-motion condition is as follows: The angle sensor connected to the micro pedal converts the driver's needs into an electrical signal; the voltage value corresponding to the opening degree of the micro pedal is found through the micro pedal angle lookup module (30), and then the system oil pressure value corresponding to the micro pedal opening degree down to the reverse gear is found through the first-order lookup module (11); the temperature sensor collects the real-time oil pan temperature value and combines it with the system oil pressure value output by the first-order lookup module (11), and finds the electromagnetic proportional valve control current value corresponding to the reverse gear through the first-order lookup module (12); At this time, the reverse gear signal corresponding to the first selection switch (41) is set to "1", the forward gear signal of the second selection switch (42) is set to "0", and the calibration and overshoot mode corresponding to the third selection switch (43) is set to "0". After the second selection switch (42) judges, the logic flow goes down path. After the first selection switch (41) judges, the logic flow goes up path. After the third selection switch (43) judges, the logic flow goes down path.

7. The control system for the forklift gearbox assembly based on an electromagnetic proportional valve according to claim 4, characterized in that, The forward micro-motion control logic route is as follows: The angle sensor connected to the micro pedal converts the driver's needs into an electrical signal; the voltage value corresponding to the opening degree of the micro pedal is found through the micro pedal angle lookup module (30), and then the system oil pressure value corresponding to the forward gear at the corresponding micro pedal opening degree is found through the second first-order lookup module (21); the real-time oil pan temperature value collected by the temperature sensor is combined with the system oil pressure value output by the second first-order lookup module (21), and the electromagnetic proportional valve control current value corresponding to the forward gear is found through the second second-order lookup module (22); At this time, the forward gear signal corresponding to the second selection switch (42) is set to "1", the reverse gear signal corresponding to the first selection switch (41) is set to "0", and the calibration and overshoot mode corresponding to the third selection switch (43) is set to "0". After the second selection switch (42) judges, the logic flow goes up path; after the first selection switch (41) judges, the logic flow goes down path; after the third selection switch (43) judges, the logic flow goes down path.

8. The control system for the forklift gearbox assembly based on an electromagnetic proportional valve according to claim 5, characterized in that, The control logic route for calibration and overshoot mode is as follows: At this time, the calibration and overshoot mode is entered. The reverse gear signal corresponding to the first selection switch (41) is set to "0", the forward gear signal corresponding to the second selection switch (42) is set to "0", and the calibration and overshoot mode input module (62) is set to "1". After the first selection switch (41) judges, the logic flow goes down path. After the second selection switch (42) judges, the logic flow goes down path. After the third selection switch (43) judges, the logic flow goes up path. The calibration and overshoot mode input module (62) outputs calibration and overshoot current according to the current curve preset in the calibration and overshoot mode current loop module (61), and outputs it through the third selection switch (43). At this time, the electromagnetic proportional valve works according to the current curve preset in the calibration and overshoot mode current loop module (61).

9. A hydraulic shifting control system for a forklift, characterized in that, The control system of the forklift gearbox assembly based on the electromagnetic proportional valve according to any one of claims 1-8 includes: an oil reservoir (1), a filter (2), an oil supply pump (3), an electromagnetic proportional valve (4), a forward gear clutch (5), a reverse gear clutch (6), and a main pressure regulating valve (7). The control system of the forklift gearbox assembly based on the electromagnetic proportional valve is communicatively connected to the electromagnetic proportional valve (4). The oil in the oil storage tank (1) is filtered by the filter (2), and the transmission oil is pressurized by the oil supply pump (3) and then divided into two paths at the outlet; after being pressured by the main pressure regulating valve (7), it is input into the oil inlet passage at the bottom of the electromagnetic proportional valve (4); The control system of the forklift gearbox assembly based on the electromagnetic proportional valve precisely controls the movement of the electromagnetic proportional valve (4) by outputting the current, thereby controlling the oil pressure of the forward gear clutch (5) and the reverse gear clutch (6) to realize the functions of each gear and micro-motion.

10. The forklift hydraulic shift control system according to claim 9, characterized in that, In neutral, the electromagnetic proportional valve (4) does not work, the valve core of the electromagnetic proportional valve (4) is in the neutral position, and there is no oil pressure in the forward and reverse clutches, so they do not engage. In forward gear, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the gear signal, increases the current of the electromagnetic coil at the S1 end of the electromagnetic proportional valve (4) proportionally, the valve core moves to the S1 end, the main oil circuit is connected to the forward gear clutch chamber, the oil pressure is established proportionally, the forward gear clutch (5) engages, and the forward gear power transmission is realized. If the micro pedal is pressed at this time, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the electrical signal converted from the opening of the micro pedal, releases the current of the electromagnetic coil at the S1 end proportionally, the valve core moves to the neutral position, reduces or cuts off the oil circuit between the main oil circuit and the forward gear clutch chamber, the forward gear clutch chamber is depressurized, and the micro function in the forward gear mode is realized. If the micro pedal is released at this time, the forward gear is restored. In reverse gear, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the gear signal, increases the current of the electromagnetic coil at the S2 end of the electromagnetic proportional valve (4) proportionally, the valve core moves to the S2 end, the main oil circuit is connected to the reverse gear clutch chamber, the oil pressure is established proportionally, the reverse gear clutch engages, and reverse gear power transmission is realized. If the micro pedal is pressed at this time, the control system of the forklift gearbox assembly based on the electromagnetic proportional valve receives the electrical signal converted from the opening of the micro pedal, releases the current of the electromagnetic coil at the S2 end proportionally, the valve core moves to the neutral position, reduces or cuts off the oil circuit between the main oil circuit and the reverse gear clutch chamber, the reverse gear clutch chamber is depressurized, and the micro function in reverse gear mode is realized. If the micro pedal is released at this time, reverse gear is restored.

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