A non-road mobile machinery walking system and a control method based thereon

Abstract

This invention provides a non-road mobile machinery walking system and a control method based thereon, relating to the field of non-road machinery. The output shaft of the gear shift transmission is connected to the rear axle. The gear shift transmission includes gear positions and hydraulic shift forks and shift synchronizers adapted to the gear positions. The oil ports of the hydraulic motor are respectively connected to the oil ports of the hydraulic pump. The input end of the controller is connected to the shift switch, speed sensor one, and speed sensor two, and the output end is connected to the electromagnetic bypass valve, the hydraulic control valve, and the hydraulic pump. This invention adds an electromagnetic bypass valve between the two oil ports of the hydraulic motor. Through the shift signal and the signals fed back to the controller from the speed sensor one of the engine output shaft and the speed sensor two of the gear shift transmission output shaft, the hydraulic shift fork is controlled to engage the shift synchronizer with the shifted gear. After engagement, the output displacement of the hydraulic pump is adjusted by the controller to achieve non-stop gear shifting of the non-road machinery.

Description

Technical Field

[0001] This invention relates to the field of non-road machinery technology, specifically to a non-road mobile machinery walking system and a control method based thereon. Background Technology

[0002] Most existing non-road mobile machinery, such as construction machinery, uses engine-driven mechanical transmission mechanisms or hydraulic torque converters with mechanical gear transmissions for high and low gear shifting. When shifting gears in such mechanical gear transmissions, the main clutch must first disengage to cut off power transmission, and then a synchronizer or engagement sleeve is operated to perform a non-stop gear shift. However, for travel mechanisms requiring hydrostatic drive (hydraulic pumps and hydraulic motors) for high and low gear shifting, a clutch-based approach is no longer feasible.

[0003] The existing walking mechanism, which uses hydrostatic drive, requires the machine to stop to shift gears because there is no clutch. This makes the machine very inconvenient to operate. Even when the machine is stopped, it is not easy to grasp the timing of gear engagement, which sometimes leads to difficulty in shifting gears or damage to the gears. Summary of the Invention

[0004] This invention addresses the aforementioned problems in the prior art by providing a non-road mobile machinery walking system and a control method based thereon, which is easy to operate, provides smooth and comfortable gear shifting, and enables stable gear shifting for acceleration or deceleration.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0006] On one hand, the present invention provides a non-road mobile machinery travel system, including a front axle and a rear axle mounted on the non-road machinery, characterized in that the travel system further includes...

[0007] Engines installed on off-road machinery

[0008] The hydraulic pump is located on the engine.

[0009] A shift transmission is installed between the front and rear axles, with its output shaft connected to the rear axle. The shift transmission contains at least two sets of gears, as well as hydraulic shift forks and shift synchronizers that are adapted to the gears.

[0010] A hydraulic motor is connected to the input shaft of the gear shift transmission. Ports A and B of the hydraulic motor are respectively connected to the ports of the hydraulic pump.

[0011] and control system; the control system includes

[0012] Speed ​​sensor 1 is located on the engine output shaft.

[0013] Speed ​​sensor two is located on the output shaft of the shift transmission.

[0014] The shift switch that controls the gear shifting of the transmission.

[0015] An electromagnetic bypass valve is installed between ports A and B of the hydraulic motor.

[0016] A hydraulic control valve connected to a gearbox and used to control the hydraulic shift fork.

[0017] and controller; among which,

[0018] The controller's input terminal is connected to the shift switch to receive upshift or downshift signals from the shift switch; the controller's input terminal is connected to speed sensor one and speed sensor two to receive engine speed signals and transmission output shaft speed signals from speed sensor one and speed sensor two, respectively.

[0019] The controller's output is connected to the solenoid bypass valve to control whether the hydraulic motor's A and B ports are connected; the controller's output is connected to the hydraulic control valve to control the hydraulic shift fork to engage the shift synchronizer with the shift gear after shifting; the controller's output is connected to the hydraulic pump to control the hydraulic pump's output displacement.

[0020] Furthermore, the hydraulic pump is an electronically controlled variable displacement hydraulic pump, and the hydraulic motor is an electronically controlled variable displacement hydraulic motor.

[0021] Furthermore, the output shaft of the shift transmission is also connected to the front axle.

[0022] Furthermore, the shift transmission is connected to the axle via a drive shaft.

[0023] Furthermore, the control system also includes a position sensor installed on the hydraulic shift fork. The position sensor is connected to the input terminal of the controller and is used to feed back the signal of whether the shift synchronizer and the shifted gear are properly engaged to the controller.

[0024] On the other hand, the present invention provides a control method based on the above-mentioned non-road mobile machinery walking system, characterized by comprising the following steps:

[0025] S1. When the controller receives a shift signal from the shift switch indicating a shift from the first gear to the second gear, it simultaneously satisfies the following conditions: the engine speed is within a set range, the output shaft speed of the shift gearbox is within a set range, and this condition is maintained for a set time.

[0026] S2. The controller controls the solenoid bypass valve to open the A port and B port of the hydraulic motor.

[0027] S3. After the delay, the controller controls the hydraulic shift fork to engage the shift synchronizer with the second gear by controlling the hydraulic control valve.

[0028] S4. After the shift synchronizer engages with the second gear, the controller controls and adjusts the output displacement of the hydraulic pump to keep the output shaft speed of the shift transmission stable before and after shifting.

[0029] S5. After the hydraulic pump output displacement reaches the target value, after a certain delay, the solenoid bypass valve is turned off to complete the gear switching. The controller controls and adjusts the hydraulic pump output displacement to the control value so that the hydraulic pump output flow is close to the motor output flow at this time.

[0030] Furthermore, when the second gear is higher than the first gear (the second gear is a high-speed gear and the first gear is a low-speed gear), the gear shifts from low-speed gear to high-speed gear. In the above scheme, in S1, the engine speed is not lower than the set threshold, the output shaft speed of the shift gearbox is not lower than the set threshold and remains so for a set time. In S4, the controller controls the reduction of the hydraulic pump's output displacement. In S5, the controller controls the increase of the hydraulic pump's output displacement to the control value.

[0031] Furthermore, in S4, the controller reduces the output displacement of the hydraulic pump to T2, and T2 / T1 < V1 / V2, where T1 is the output displacement of the hydraulic pump before shifting, V1 is the output shaft speed of the transmission in the first gear, and V2 is the output shaft speed of the transmission in the second gear.

[0032] Furthermore, when the second gear is lower than the first gear (the first gear is a high gear and the second gear is a low gear), the gear shifts from high gear to low gear. In the above scheme, in S1, the engine speed does not exceed the set threshold, the output shaft speed of the shift gearbox does not exceed the set threshold and remains so for a set time. In S4, the controller controls to increase the output displacement of the hydraulic pump. In S5, the controller controls to reduce the output displacement of the hydraulic pump to the appropriate control value.

[0033] Furthermore, in S4, the controller controls the increase of the hydraulic pump's output displacement to T2, and T2 / T1 > V1 / V2, where T1 is the hydraulic pump's output displacement before shifting, V1 is the output shaft speed of the transmission in the first gear, and V2 is the output shaft speed of the transmission in the second gear.

[0034] The beneficial effects of this invention are as follows: This invention creatively adds an electromagnetic bypass valve between the two oil ports of the hydraulic motor, and in conjunction with the set control system, it controls the hydraulic shift fork to engage the shift synchronizer with the shift gear after shifting by using the shift signal and the signals fed back to the controller by the engine output shaft speed sensor one and the shift transmission output shaft speed sensor two. After the engagement is in place, the controller adjusts the output displacement of the hydraulic pump to keep the speed of the shift transmission output shaft stable before and after shifting, and finally realizes non-stop shifting of non-road machinery, and the shifting is smooth and comfortable. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the non-road mobile machinery walking system of the present invention;

[0036] Figure 2 This is a schematic diagram of the shift transmission of the present invention;

[0037] Figure 3 yes Figure 2 A cross-sectional view of the gear shift transmission shown.

[0038] Figure 4 yes Figure 2 A cross-sectional view of the gear shift transmission shown.

[0039] Figure 5 This is a connection block diagram of the control system of the present invention;

[0040] Figure 6 This is a flowchart of the control method of the present invention (switching from low speed to high speed);

[0041] Figure 7 This is a flowchart of the control method of the present invention (switching from high speed to low speed);

[0042] Figure 8 This is a graph showing the relationship between the displacement of the hydraulic pump and the control current used in an embodiment of the present invention;

[0043] In the diagram: 1. Engine, 2. Hydraulic pump, 3. Gearbox, 31. Hydraulic shift fork, 32. Shift synchronizer, 33. Hydraulic control valve, 4. Rear axle, 5. Front axle, 6. Hydraulic motor, 7. Solenoid bypass valve, 8. Controller, 91. Speed ​​sensor one, 92. Speed ​​sensor two, 93. Shift switch, 94. Position sensor, 10. Drive shaft. Detailed Implementation

[0044] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0045] As attached Figure 1-5As shown, this embodiment provides a non-road mobile machinery travel system, which includes a front axle 5 and a rear axle 4 mounted on the non-road machinery. The travel system also includes...

[0046] Engine 1, installed on off-road machinery

[0047] The hydraulic pump 2, located on the engine, is specifically an electronically controlled variable displacement hydraulic pump.

[0048] The shift transmission 3 is disposed between the front axle and the rear axle. The output shaft of the shift transmission 3 is connected to the rear axle 4 via a drive shaft 10 (in other embodiments of the present invention, the output shaft of the shift transmission 3 can also be connected to the front axle 5 simultaneously). The shift transmission 3 includes a hydraulic shift fork 31, a shift synchronizer 32, and at least two sets of gears. The hydraulic shift fork 31 is connected to a hydraulic control valve 33.

[0049] The hydraulic motor 6, which is connected to the input shaft of the gear shift transmission 3, is specifically an electronically controlled variable displacement hydraulic motor. The A port and B port of the hydraulic motor 6 are respectively connected to the two ports of the hydraulic pump 2.

[0050] and a control system; the control system includes

[0051] Speed ​​sensor 91 is located on the output shaft of engine 1.

[0052] Speed ​​sensor 292 is located on the output shaft of gearbox 3.

[0053] The shift switch 93 controls the shift transmission 3.

[0054] The solenoid bypass valve 7 is located between the A and B ports of the hydraulic motor 6.

[0055] and controller 8; among which,

[0056] The input terminal of the controller 8 is connected to the shift switch 93 to receive upshift or downshift signals from the shift switch; the input terminal of the controller 8 is connected to speed sensor 1 91 and speed sensor 2 92 to receive engine speed signals and output shaft speed signals from speed sensor 1 91 and speed sensor 2 92, respectively.

[0057] The output of controller 8 is connected to electromagnetic bypass valve 7 to control whether the A port and B port of hydraulic motor 6 are connected; the output of controller 8 is connected to hydraulic control valve 33 to control hydraulic shift fork 31 to move shift synchronizer 32 to mesh with the shift gear after shifting; the output of controller 8 is connected to hydraulic pump 2 to control the output displacement of hydraulic pump 2.

[0058] This embodiment uses a two-speed transmission with a gear shift reducer as an example. The control method is as follows:

[0059] 1. Shifting from a low gear to a high gear (see...) Figure 6 (As shown)

[0060] Preset the following parameters: (1) the engine speed is not lower than the set value, and (2) the output shaft speed of the gearbox is not lower than the set value and continues for a set time (e.g., more than 1.5 seconds).

[0061] S1. First, switch the low speed switch to the high speed switch. When the controller receives the shift signal from the shift switch to the high speed, and at the same time meets the above parameter conditions, namely, the engine speed is within the set range, the output shaft speed of the shift gearbox is within the set range and continues for the set time.

[0062] S2. The controller controls the solenoid bypass valve to open the A and B ports of the hydraulic motor, allowing the wheels to move freely.

[0063] S3. After a certain delay, the controller controls the hydraulic shift fork to engage the shift synchronizer with the high-speed gear by controlling the hydraulic control valve.

[0064] S4. After the shift synchronizer engages with the second gear, the controller reduces the hydraulic pump's output displacement to T2 to keep the transmission output shaft speed stable before and after the shift, where T2 / T1 < V1 / V2. T1 is the hydraulic pump's output displacement before the shift, V1 is the transmission output shaft speed in the first gear, and V2 is the transmission output shaft speed in the second gear. For example, assuming the ratio of the high gear to the low gear output speed is 3:1, the hydraulic pump's output displacement at the current speed is reduced to less than one-third of its pre-shift displacement, achieving a similar theoretical displacement before and after the shift, thus minimizing the change in transmission output shaft speed.

[0065] S5. After the hydraulic pump output displacement reaches the target value, after a certain delay, the solenoid bypass valve is turned off to complete the switch from low speed to high speed. The controller controls the hydraulic pump output displacement to increase from one-third of the shift value to the control value, so that the hydraulic pump output flow is close to the motor output flow at this time, achieving smooth shifting and speed increase.

[0066] The control process described above is explained below with specific examples:

[0067] In the following example, it is known

[0068] Hydraulic pump output flow (mL / min) = displacement * speed * efficiency;

[0069] Hydraulic motor required flow rate (mL / min) = displacement * speed / efficiency;

[0070] The gear shifting transmission reverse-drives the hydraulic motor. The hydraulic motor output flow (mL / min) = displacement * speed * efficiency;

[0071] The relationship between the hydraulic pump's displacement and control current is shown in the figure. Figure 8 As shown.

[0072] Before shifting gears, the hydraulic pump output drives the hydraulic motor to work. Assuming the maximum displacement of the hydraulic pump is 53 (mL / r), the engine speed is 2400 (r / min), the hydraulic pump efficiency is 0.95, the hydraulic motor displacement is 47 (mL / r), and the hydraulic motor volumetric efficiency is 0.96.

[0073] The output flow rate of the hydraulic pump is: A1 = 53 * 2400 * 0.95 = 120840 (mL);

[0074] The drive is a closed system, and the output speed of the hydraulic motor is: V10=A1*0.96 / 47=2468(r / min);

[0075] If the low gear reduction ratio of the transmission is 4, then the output shaft speed of the transmission is V20 = V10 / 4 = 617 (r / min).

[0076] When shifting gears, the solenoid bypass valve bypasses the hydraulic pump and hydraulic motor, allowing them to operate independently. At this time, the hydraulic motor is driven by the wheel, and the hydraulic motor is equivalent to the pump working. The discharge flow of the hydraulic motor is calculated according to the output flow of the hydraulic pump. Since there is resistance when the vehicle is moving, the wheel is slowing down. Let's assume the speed drops to 600 (r / min).

[0077] When the high gear reduction ratio of the gearbox is 1.31, the output flow of the hydraulic motor is: A2 = 47 * 600 * 1.31 * 0.96 = 35460 (mL).

[0078] To ensure smooth operation after gear shifting, the output flow of the hydraulic pump is adjusted to be close to that of the hydraulic motor, approximately 35,000 mL. Since the engine speed is not reduced, this can only be achieved by adjusting the displacement. The displacement adjustment value of the hydraulic pump is: A3 = 35,000 / (2400 * 0.95) = 15.35 mL / r.

[0079] At this point, the pump displacement percentage is: 15.35 / 53 * 100% = 28.96%; then according to Figure 8 The diagram shows the linear relationship between the hydraulic pump's displacement and control current. The control current can be obtained from the percentage of the pump's displacement. Figure 8The curves shown are only used to illustrate the relevant parameters of the hydraulic pump (the pump itself is prior art) in the case shown in this case, to explain the process of adjusting the pump displacement by actually controlling the control current of the hydraulic pump, and are not intended to limit this case.

[0080] 2. Shifting from a high gear to a low gear (see...) Figure 7 (As shown)

[0081] Preset the parameter conditions: (1) the engine speed is not higher than the set value, and (2) the output shaft speed of the gearbox is not higher than the set value and continues for a set time (e.g., more than 1.5 seconds).

[0082] S1. First, switch the high speed switch to the low speed switch. When the controller receives the shift signal from the shift switch to the low speed, and at the same time meets the above parameter conditions, namely, the engine speed is within the set range, the output shaft speed of the shift gearbox is within the set range and continues for the set time.

[0083] S2. The controller controls the solenoid bypass valve to open the A and B ports of the hydraulic motor, allowing the wheels to move freely.

[0084] S3. After a certain delay, the controller controls the hydraulic shift fork to engage the shift synchronizer with the low-speed gear by controlling the hydraulic control valve.

[0085] S4. The hydraulic shift fork position sensor detects whether the shift synchronizer and the low-speed gear are properly engaged and sends feedback to the controller. When the controller receives the signal from the position sensor indicating that the shift synchronizer and the low-speed gear are properly engaged, the controller reduces the output displacement of the hydraulic pump to T2 to keep the output shaft speed of the transmission stable before and after shifting. Here, T2 / T1 > V1 / V2, where T1 is the output displacement of the hydraulic pump before shifting, V1 is the output shaft speed of the transmission in the first gear, and V2 is the output shaft speed of the transmission in the second gear. For example, assuming the ratio of the high-speed to low-speed output speeds of the transmission is 3:1, the hydraulic pump's output displacement at the current speed is increased to more than three times that before the shift, achieving a similar theoretical displacement before and after the shift, thus ensuring that the output shaft speed of the transmission does not change significantly before and after the shift.

[0086] S5. After the hydraulic pump and hydraulic motor reach the target displacement, the solenoid bypass valve is turned off after a certain delay to complete the shift from low speed to high speed. The controller controls the output displacement of the hydraulic pump to increase from one-third of the shift value to the control value, so that the output flow of the hydraulic pump is close to the output flow of the motor at this time, thus achieving smooth shifting and speed reduction.

[0087] Note: The above Figure 6 and Figure 7The parameters listed, such as 2200 RPM, 600 RPM, and delay time, are for illustrative purposes only and are not intended to limit the scope of this solution.

[0088] In another preferred embodiment of the present invention, based on the above embodiments, the control system further includes a position sensor 94 disposed on the hydraulic shift fork. The position sensor is connected to the input terminal of the controller 8 and is used to feed back a signal indicating whether the shift synchronizer and the shifted gear are properly engaged to the controller. In step S4, when the controller detects the signal from the position sensor indicating that the shift synchronizer and the shifted gear are properly engaged, the controller then controls and adjusts the output displacement of the hydraulic pump. Its advantage is that it can reduce damage to components such as the shift synchronizer and the shift gear.

Claims

1. A control method based on a non-road mobile machinery travel system, wherein the non-road mobile machinery travel system includes: Front and rear axles installed on non-road mobile machinery Engines installed on non-road mobile machinery The hydraulic pump is located on the engine. A shift transmission is installed between the front and rear axles, with its output shaft connected to the rear axle. The shift transmission contains at least two sets of gears, as well as hydraulic shift forks and shift synchronizers that are adapted to the gears. A hydraulic motor is connected to the input shaft of the gear shift transmission. Ports A and B of the hydraulic motor are respectively connected to the ports of the hydraulic pump. Control system; It includes: Speed ​​sensor 1 is located on the engine output shaft. Speed ​​sensor two is located on the output shaft of the shift transmission. The shift switch that controls the gear shifting of the transmission. An electromagnetic bypass valve is installed between ports A and B of the hydraulic motor. A hydraulic control valve connected to a gearbox and used to control the hydraulic shift fork. Controller; where, The controller's input terminal is connected to the shift switch to receive upshift or downshift signals from the shift switch; the controller's input terminal is connected to speed sensor one and speed sensor two to receive engine speed signals and transmission output shaft speed signals from speed sensor one and speed sensor two, respectively. The controller's output is connected to the solenoid bypass valve to control the on / off state between the A and B ports of the hydraulic motor; the controller's output is connected to the hydraulic control valve to control the hydraulic shift fork to engage the shift synchronizer with the shift gear after shifting; the controller's output is connected to the hydraulic pump to control the output displacement of the hydraulic pump. The control method is characterized by comprising the following steps: S1. When the controller receives a shift signal from the shift switch indicating a shift from the first gear to the second gear, it simultaneously satisfies the following conditions: the engine speed is within the set range, the output shaft speed of the shift transmission is within the set range, and this condition is maintained for a set time. S2. The controller controls the solenoid bypass valve to open the A port and B port of the hydraulic motor. S3. After the delay, the controller controls the hydraulic shift fork to engage the shift synchronizer with the second gear by controlling the hydraulic control valve. S4. After the shift synchronizer engages with the second gear, the controller controls and adjusts the output displacement of the hydraulic pump to keep the output shaft speed of the shift transmission stable before and after shifting. S5. When the output displacement of the hydraulic pump reaches the target value, after a certain delay, the solenoid bypass valve is turned off to complete the gear switching. The controller controls and adjusts the output displacement of the hydraulic pump to the control value so that the output flow of the hydraulic pump is close to the output flow of the motor at this time. When the second gear is higher than the first gear, in S1 the engine speed is not lower than the set threshold, the output shaft speed of the shift transmission is not lower than the set threshold and continues for a set time, in S4 the controller controls to reduce the output displacement of the hydraulic pump, and in S5 the controller controls to increase the output displacement of the hydraulic pump to the control value. When the second gear is lower than the first gear, in S1 the engine speed does not exceed the set threshold, the output shaft speed of the shift transmission does not exceed the set threshold and remains so for a set time, in S4 the controller controls to increase the output displacement of the hydraulic pump, and in S5 the controller controls to reduce the output displacement of the hydraulic pump to the control value.

2. The control method according to claim 1, characterized in that, The hydraulic pump is an electronically controlled variable displacement hydraulic pump.

3. The control method according to claim 1, characterized in that, The output shaft of the shift transmission is also connected to the front axle.

4. The control method according to claim 1, characterized in that, The control system also includes a position sensor installed on the hydraulic shift fork. The position sensor is connected to the input terminal of the controller and is used to feed back the signal to the controller whether the shift synchronizer and the shifted gear are properly engaged.

5. The control method according to claim 1, characterized in that, When the second gear is higher than the first gear, the controller in S4 controls the hydraulic pump to reduce the output displacement to T2, and T2 / T1 < V1 / V2, where T1 is the output displacement of the hydraulic pump before shifting, V1 is the output shaft speed of the transmission in the first gear, and V2 is the output shaft speed of the transmission in the second gear.

6. The control method according to claim 1, characterized in that, When the second gear is lower than the first gear, the controller in S4 controls the increase of the hydraulic pump output displacement to T2, and T2 / T1>V1 / V2, where T1 is the hydraulic pump output displacement before shifting, V1 is the output shaft speed of the transmission in the first gear, and V2 is the output shaft speed of the transmission in the second gear.

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