WO2013040780A1

WO2013040780A1 - Control system for variable displacement pump and hydraulic travelling equipment

Info

Publication number: WO2013040780A1
Application number: PCT/CN2011/080023
Authority: WO
Inventors: 张良军; 龙亮; 刘伯祥; 吴小云
Original assignee: 长沙中联重工科技发展股份有限公司; 湖南中联重科专用车有限责任公司
Priority date: 2011-09-22
Filing date: 2011-09-22
Publication date: 2013-03-28

Abstract

Disclosed is a control system for a variable displacement pump, which system comprises a variable displacement pump control mechanism (1), an oil outlet pipeline (11) of which variable displacement pump control mechanism is in communication with a pressure control port (21A) of a displacement control device (21) of the variable displacement pump (2), wherein the variable displacement pump control system also comprises a pressure limiting branch (3) bypassing from the oil outlet pipeline, and the pressure limiting branch is activated when the pressure in an oil supply pipeline (22) of the variable displacement pump is greater than or equal to a predefined value; and the pressure limiting branch is deactivated when the pressure is less than the predefined value. Also disclosed is hydraulic travelling equipment, comprising a travel motor (5) and a variable displacement pump (2) driving the travel motor (5), the variable displacement pump being controlled via the abovementioned control system for a variable displacement pump. The variable displacement pump control mechanism in the variable displacement pump control system is easy to operate, and, when used for driving hydraulic travelling equipment, does not tend to damage the engine due to incorrect operation by a driver.

Description

Variable pump control system and hydraulic walking equipment

Technical field

The present invention relates to the field of variable pump control, and in particular to a control system for a variable pump, and to a hydraulic running device. Background technique

In a conventional hydraulic vehicle such as a sweeping vehicle, a traveling motor is generally used to drive the traveling equipment to travel, and the traveling motor is usually driven by a variable pump, and the rotation of the traveling motor is controlled by controlling the rotation direction and displacement of the variable pump. Direction and speed to control the direction of travel (forward or backward) and travel speed of the hydraulic walking equipment.

Variable pumps usually come with displacement control devices, such as swash plate displacement control devices. Existing variable pump control systems typically include variable pump control mechanisms such as foot pedal valves or handle valves. The oil discharge line of the variable pump control mechanism communicates with the pressure control port of the displacement control device of the variable pump, so that the driver controls the variable displacement control device of the variable pump by operating the variable pump control mechanism to control the displacement of the variable pump. For example, more specifically, the driver steps on the foot pedal valve at an angle such that the hydraulic oil in the oil discharge line of the foot pedal valve has a corresponding pressure which acts on the displacement control device of the variable pump, so that the variable The pump outputs the corresponding displacement. Therefore, the larger the angle at which the foot pedal valve is depressed, the larger the displacement of the variable pump, and conversely, the smaller the angle at which the foot pedal valve is depressed, the smaller the displacement of the variable pump.

The output power of the variable pump is proportional to the product of the displacement of the variable pump and the output pressure of the variable pump (ie the pressure of the variable pump's supply line). Therefore, during the normal walking of the traveling machine, if the output pressure of the variable pump is large (that is, a large output torque is required) at the same power, it is usually necessary to reduce the displacement of the variable pump (ie, reduce the walking speed). If the output pressure of the variable pump is small (ie, the required output torque is small), it is usually necessary to increase the displacement of the variable pump (ie, obtain a comparison) Big walking speed). The output pressure (torque) of the variable pump is related to the load of the traveling motor, and the load of the traveling motor is determined by the road condition. If driving on a flat road, the load on the travel motor is small, and the output pressure (torque) of the variable pump is small. If you want a faster travel speed, you should step on the pedal valve at a relatively large angle; On an uphill road, the load on the travel motor is large, and the output pressure (torque) of the variable pump is large. If you want to output a large climb torque at the same power, you should step on the foot pedal valve and make a smaller one. angle. This angle is very difficult to locate. It can only be judged by the driver's own experience and according to the engine's rotating condition (such as listening to sounds). This makes constant adjustments to find an ideal walking state, so the operation is complicated and labor-intensive. In addition, as mentioned above, when the traveling machine is going uphill, the speed-down driving must be lifted up to reduce the pedaling angle of the foot pedal valve. This is contrary to the operating habit of the driver who usually steps on the accelerator pedal. Habitually mistakenly stepping the foot pedal valve to the end, causing the variable pump to output the maximum flow rate, that is, climbing at the maximum speed. At this time, the load is maximum, and the traveling machine works at the maximum speed and the maximum torque, which will greatly deplete the life of the engine; If the engine power is not large enough, the engine will suddenly turn off and cause a traffic accident during driving. Summary of the invention

It is an object of the present invention to provide a variable pump control system in which a variable pump control mechanism is easy to operate, for example, when used to drive a hydraulic traveling device, it is not easily caused to the engine by a driver's misoperation. Damage and cause a traffic accident.

In order to achieve the above object, in one aspect, the present invention provides a control system for a variable pump, the control system of the variable pump including a variable pump control mechanism, the pressure of the oil discharge line of the variable pump control mechanism and the displacement control device of the variable pump a control port communication, wherein the variable pump control system further includes a pressure limiting branch bypassing the oil discharge line of the variable pump control mechanism, and when the pressure in the oil supply line of the variable pump is greater than or equal When the predetermined value is reached, the pressure limiting branch is turned on; when the pressure in the oil supply line of the variable pump is less than the predetermined value, the pressure limiting branch is disconnected.

Preferably, the pressure limiting branch includes an overflow valve and an on-off valve connected in series with each other. Preferably, the control system of the variable pump further comprises a controller and a pressure detecting device disposed on the oil supply line of the variable pump, the pressure detecting device and the switching valve being connected to the controller.

Preferably, the pressure detecting device is a pressure relay or a pressure transmitter.

Preferably, the variable pump is a bidirectional variable pump, and the pressure detecting devices are respectively disposed on two oil supply lines of the bidirectional variable pump.

Preferably, the displacement control device of the variable pump is a swash plate displacement control device.

Preferably, the variable pump control mechanism comprises a foot pedal valve or a handle valve.

Preferably, the on-off valve is a two-position two-way solenoid valve.

In another aspect, the present invention also provides a hydraulic running device including a traveling motor and a variable pump that drives the traveling motor, wherein the hydraulic running device employs a variable pump control system as described above. The variable pump is controlled.

Preferably, the hydraulic running device is a sweeping vehicle.

With the above technical solution, when the pressure in the oil supply line of the variable pump is greater than or equal to a predetermined value, the pressure limiting branch is turned on, and the actual output pressure of the variable pump control mechanism such as the foot pedal valve is limited at this time. That is, even if the driver mis-operates so that the variable pump control mechanism outputs the maximum pressure, the actual output pressure is limited to the pressure of the pressure limiting branch, so that the displacement of the variable pump is also limited to a predetermined value, so that the hydraulic pressure The walking speed of the traveling machine is also limited, so that the output power of the variable pump is also limited, and it is not easy to cause an excessive output power due to a driver's misoperation, thereby causing damage to the engine and causing a traffic accident.

Other features and advantages of the invention will be described in detail in the detailed description which follows. DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are in the In the drawing:

1 is a schematic schematic diagram of a control system of a variable pump in accordance with an embodiment of the present invention;

Fig. 2 is a view showing the relationship between the operation of the variable pump control mechanism and the change of the displacement of the variable pump when the pressure limiting branch of the control system of the variable pump shown in Fig. 1 is turned on. Description of the reference numerals

I variable pump control mechanism; 2 variable pump;

21 displacement control device; 21A pressure control port;

II oil discharge pipeline; 3 pressure limiting branch;

22 oil supply pipeline; 31 relief valve;

32 on-off valve; 4 pressure detection device;

5 Travel motor. detailed description

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are intended to be illustrative and not restrictive.

As shown in FIG. 1 , according to an embodiment of the present invention, a control system of a variable pump is provided. The control system of the variable pump includes a variable pump control mechanism 1 , and an oil discharge line and a variable pump of the variable pump control mechanism 1 . The pressure control port 21A of the displacement control device 21 of 2 is in communication, wherein the variable pump control system further includes a pressure limiting branch 3 bypassing the oil discharge line 11 of the variable pump control mechanism 1, and The pressure in the oil supply line 22 of the variable pump 2 is greater than or equal to a predetermined value

(The magnitude of the predetermined value may be determined according to actual conditions, for example, may be determined according to the rated power or power curve of the engine that drives the variable pump 2), the voltage limiting branch 3 is turned on; when the variable pump 2 The pressure limiting branch when the pressure in the oil supply line 22 is less than the predetermined value 3 disconnected.

With the above technical solution, when the pressure in the oil supply line 22 of the variable pump 2 is greater than or equal to a predetermined value, the pressure limiting branch 3 is turned on, and at this time, the actual value of the variable pump control mechanism 1 (for example, a foot pedal valve) The output pressure is limited. That is, even if the driver mis-operates so that the variable pump control mechanism 1 outputs the maximum pressure, the actual output pressure is limited to the pressure of the pressure limiting branch 3, so that the displacement of the variable pump 2 is also limited to a predetermined value. Therefore, the traveling speed of the hydraulic traveling machine is also limited, so that the output power of the variable pump 2 is also limited, and it is not easy to cause an excessive output power due to a driver's misoperation, thereby causing damage to the engine and causing a traffic accident.

More specifically, Fig. 2 shows the relationship between the stepping angle of the foot pedal valve and the displacement of the variable pump 2 when the variable pump control mechanism 1 is a foot pedal valve as an example. In the figure, Pr is the pressure of the pressure limiting branch 3, and Ar is the pedaling angle of the foot pedal valve when the output pressure of the foot pedal valve is equal to the pressure Pr of the pressure limiting branch 3. As shown in Fig. 2, with Ar as the inflection point, when the pedaling angle of the foot pedal valve is smaller than Ar, the displacement of the variable displacement pump 2 changes with the change of the pedaling angle; when the pedaling angle of the foot pedal valve is larger than Ar, The displacement of the variable pump 2 is always constant, which is equal to the displacement corresponding to the stepping angle of Ar. That is to say, when the pressure limiting branch 3 is turned on, the pedaling angle of the foot pedal valve acts in a section smaller than Ar; when the pedaling angle of the foot pedal valve is larger than Ar, the displacement of the hydraulic pump 2 is still Ar The corresponding displacement does not increase with the increase of the pedaling angle, thus avoiding the high-load walking of the hydraulic traveling equipment using the variable pump, so it is not easy to cause the output power due to the driver's misoperation. Excessively large damage to the engine and cause traffic accidents.

The pressure limiting branch 3 can be implemented in various suitable forms, for example as a simple and effective embodiment, as shown in Fig. 1, the pressure limiting branch 3 can comprise a relief valve 31 and a switch connected in series with each other. Valve 32. The pressure of the pressure limiting branch 3 is an overflow value set by the relief valve 31, and the limiting pressure branch 3 can be conveniently turned on or off by the switching valve 32. The on-off valve 32 can take various suitable forms. For example, as shown in FIG. 1, the on-off valve 32 is a two-position two-way solenoid valve, and more specifically, a two-position two-way electromagnetic ball valve. The switching valve 32 can be operated manually, preferably automatically. As shown in FIG. 1, the control system of the variable pump further includes a controller (not shown) and a pressure detecting device 4 disposed on the oil supply line 22 of the variable pump 2, the pressure detecting device 4 And the switching valve 32 is connected to the controller. Thereby, the pressure on the oil supply line 22 of the variable pump 2 can be detected in real time by the pressure detecting means 4, and the controller automatically controls the opening and closing of the switching valve 32 based on the pressure. When the pressure in the oil supply line 22 of the variable pump 2 is greater than or equal to a predetermined value, the controller controls the opening and closing valve 32 to open to cause the pressure limiting branch 3 to be turned on; when the variable pressure pump 2 is supplied with a fuel supply pipe When the pressure in the road 22 is less than the predetermined value, the controller controls the on-off valve 32 to close such that the pressure limiting branch 3 is opened. The pressure detecting device 4 can take various suitable forms, such as a pressure relay or a pressure transmitter. The controller may also take various suitable forms, such as a PLC or the like, and may be embedded in the control system of the hydraulic traveling machine to which the variable pump 2 is applied.

The variable pump may be a two-way variable pump, and the two oil supply lines 22 of the two-way variable pump are provided with the pressure detecting device 4, respectively. The hydraulic traveling machine can be controlled to advance or retreat by controlling the direction of rotation of the bidirectional variable pump. The pressure presets set for the two oil supply lines 22 of the bidirectional variable pump can be set separately according to the specific working conditions, and the two pressure predetermined values may be the same or different.

The displacement control device 21 of the variable pump 2 is usually provided by the variable pump 2, and various appropriate forms can be employed depending on the specific form of the variable pump 2, for example, a swash plate type displacement control device.

The variable pump control mechanism 1 can also be in various specific forms, for example, can include a handle valve or a foot pedal valve as described above.

In another aspect, the present invention also provides a hydraulic running device comprising a traveling motor 5 and a variable pump 2 driving the traveling motor 5, wherein the hydraulic running device employs a variable pump as described above A control system is used to control the variable pump 2. Of course, the variable pump control system can also be applied to other applications than hydraulic running equipment.

The hydraulic running device may be a hydraulic running device in various fields, and may be, for example, a sweeping vehicle in the field of sanitation machinery. The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments, and various simple modifications of the technical solutions of the present invention may be made within the scope of the technical idea of the present invention. These simple variations are within the scope of the invention.

It should be further noted that the specific technical features described in the above specific embodiments may be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not be further described in various possible combinations.

In addition, any combination of various embodiments of the invention may be made, as long as it does not deviate from the idea of the invention, and should also be regarded as the disclosure of the invention.

Claims

Rights request

1. A control system for a variable pump, the variable pump control system comprising a variable pump control mechanism (1), the displacement control of the oil supply line (11) and the variable pump (2) of the variable pump control mechanism (1) The pressure control port (21A) of the device (21) is in communication, characterized in that the variable pump control system further comprises a pressure limiting branch bypassing the oil discharge line (11) of the variable pump control mechanism (1) (3), and, when the pressure in the oil supply line (22) of the variable pump (2) is greater than or equal to a predetermined value, the pressure limiting branch (3) is turned on; when the variable pump (2) When the pressure in the oil supply line (22) is less than the predetermined value, the pressure limiting branch (3) is disconnected.

The variable pump control system according to claim 1, characterized in that the pressure limiting branch (3) comprises a relief valve (31) and an on-off valve (32) connected in series with each other.

3. The variable pump control system according to claim 2, wherein the variable pump control system further comprises a controller and a pressure disposed on the oil supply line (22) of the variable pump (2) A detecting device (4), the pressure detecting device (4) and the switching valve (32) are connected to the controller.

4. A control system for a variable displacement pump according to claim 3, wherein said pressure detecting means (4) is a pressure relay or a pressure transmitter.

The variable pump control system according to claim 3 or 4, wherein the variable pump (2) is a bidirectional variable pump, and the two oil supply lines (22) of the bidirectional variable pump are respectively disposed. There is the pressure detecting device (4).

6. The variable pump control system according to claim 1, wherein the displacement control device (21) of the variable pump (2) is a swash plate type displacement control device.

The variable pump control system according to claim 1, characterized in that the variable pump control mechanism (1) comprises a foot pedal valve or a handle valve.

The variable pump control system according to claim 2, wherein the switching valve (32) is a two-position two-way solenoid valve.

A hydraulic running device comprising a traveling motor (5) and a variable pump (2) for driving the traveling motor (5), characterized in that the hydraulic running device is according to claims 1 to 8. The variable pump control system of any of the above described to control the variable pump (2).

10. The hydraulic traveling apparatus according to claim 9, wherein the hydraulic traveling device is a cleaning vehicle.