CN215257684U - Hydrostatic drive system - Google Patents
Hydrostatic drive system Download PDFInfo
- Publication number
- CN215257684U CN215257684U CN202120368512.9U CN202120368512U CN215257684U CN 215257684 U CN215257684 U CN 215257684U CN 202120368512 U CN202120368512 U CN 202120368512U CN 215257684 U CN215257684 U CN 215257684U
- Authority
- CN
- China
- Prior art keywords
- pump
- drive system
- oil passage
- hydrostatic drive
- pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Fluid-Pressure Circuits (AREA)
Abstract
A hydrostatic drive system comprising: a closed variable displacement pump (1); and a variable displacement motor (2) forming a closed-loop drive circuit with the pump (1) through first and second main oil passages, one of which is a pump output side oil passage and the other is a pump intake side oil passage when the closed-type variable displacement pump is in operation; a crossover oil passage (L3) that is connected between the first and second main oil passages and is equipped with normally closed first and second brake switch valves; a relief oil passage (L4) connected to an intermediate portion of the crossover oil passage (L3) between the first and second brake switching valves, a proportional relief valve (10) being disposed in the relief oil passage (L4); and a drag torque controller (13) configured to control operations of the first and second brake switching valves and the proportional relief valve (10). The power source can be prevented from being damaged due to the fact that the power source bears overlarge dragging torque.
Description
Technical Field
The present application relates to a hydrostatic drive system having a hydrostatic braking function.
Background
Hydrostatic drives are widely used in agricultural and forestry machines, construction machines, and rail vehicles. The hydrostatic drive is used here both for driving the vehicle and for driving the work apparatus. The hydrostatic braking method is also adopted for service braking of the hydrostatic drive vehicle in the prior art. When braking is needed, the displacement of the plunger pump is reduced; on the other hand, when the vehicle is descending a slope, the hydraulic motor is still rotating at a high speed due to the inertia of the machine. In both cases, the flow at the outlet of the hydraulic motor will be greater than the demand flow at the inlet of the plunger pump, causing the outlet pressure of the hydraulic motor to rise and the inlet pressure to drop; the kinetic energy of the vehicle drives the motor to change the motor into a pump working condition, the pump changes the motor working condition to drag the engine, and the kinetic energy of the vehicle is converted into heat energy which is absorbed by the engine and the hydraulic system, so that the braking effect is achieved. However, during such braking, the engine may experience a reverse drag torque that, if too great, may cause damage to the engine.
SUMMERY OF THE UTILITY MODEL
It is an object of the present application to provide a hydrostatic drive system capable of performing hydrostatic braking that avoids damage to a power source (e.g., an engine) from being subjected to excessive drag torque.
To this end, the present application provides in one of its aspects a hydrostatic drive system comprising:
a closed variable displacement pump; and
the variable displacement pump comprises a variable displacement motor and a pump, wherein the variable displacement motor and the pump form a closed-loop hydraulic driving circuit through a first main oil passage and a second main oil passage;
wherein the hydrostatic drive system further comprises:
a crossover oil passage connected between the first and second main oil passages and equipped with normally closed first and second brake switch valves;
an overflow oil path connected to a middle portion of the crossover oil path between the first and second brake switching valves, the overflow oil path having a proportional overflow valve disposed therein; and
a drag torque controller configured to control operation of the first and second brake switch valves and the proportional relief valve.
In one embodiment, the drag torque controller is configured to determine an electrical signal to the proportional relief valve based on the allowable pump suction side pressure, the electrical signal determining the opening pressure of the proportional relief valve.
In one embodiment, the relief oil passage leads to a tank.
In one embodiment, the drag torque controller is configured to connect the relief oil passage to the pump intake side oil passage and keep the relief oil passage disconnected from the pump output side oil passage when the pressure of the pump intake side oil passage is higher than the pressure of the pump output side oil passage.
In one embodiment, the hydrostatic drive system further includes a return line having first and second check valves disposed therein, the return line opening to an intermediate portion of the return line between the first and second check valves.
In one embodiment, the hydrostatic drive system further includes an additional return oil passage connected to an intermediate portion of the return oil passage between the first and second check valves and leading to the oil tank, and the additional return oil passage is provided with a normally closed return on-off valve therein.
In one embodiment, the drag torque controller is configured to, when the pressure of the pump intake side oil passage is higher than the pressure of the pump output side oil passage, connect the relief oil passage to the pump intake side oil passage, keep the relief oil passage disconnected from the pump output side oil passage, and open the return switch valve.
In one embodiment, the hydrostatic drive system further includes a speed controller configured to control the displacement of the closed variable displacement pump and the variable motor.
In one embodiment, the speed controller is configured to reduce a displacement of the closed variable displacement pump when the hydrostatic drive system performs a hydrostatic braking operation.
In one embodiment, the opening pressure of the proportional relief valve is set to be not higher than an allowable pump suction side pressure that depends on a motoring torque that a power source driving the closed type variable displacement pump can withstand.
According to the application, in the operation process (especially the hydrostatic braking process) of the hydrostatic driving system, if the oil pressure on the pump suction side (the motor outlet side) is higher than a certain limit value, the hydraulic oil on the pump suction side overflows, the oil pressure on the pump suction side is ensured not to be too high, and the power source of the hydrostatic driving system is prevented from being damaged due to too large dragging torque.
Drawings
The foregoing and other aspects of the present application will be more fully understood from the following detailed description, taken with reference to the accompanying drawings, in which:
FIG. 1 is a fluid circuit diagram of a hydrostatic drive system according to one possible embodiment of the present application;
FIG. 2 is a schematic diagram of a control scheme of the hydrostatic drive system;
FIG. 3 is a fluid circuit diagram of a hydrostatic drive system according to another possible embodiment of the present application;
FIG. 4 is a fluid circuit diagram of a hydrostatic drive system according to yet another possible embodiment of the present application.
Detailed Description
The present application relates generally to a hydrostatic drive system that is particularly suited for driving various agricultural and forestry work machines, construction machines, rail work vehicles, and the like.
A hydrostatic drive system according to one possible embodiment of the present application is represented schematically in fig. 1, wherein the hydrostatic drive system essentially comprises: a closed type variable displacement pump 1, such as a plunger pump, is driven by a power source (particularly, an engine or an electric motor) not shown in the drawings, and a hydraulic motor 2 connected to the pump 1 through first and second main oil passages (working oil passages) L1, L2. The motor 2 is a variable displacement motor, such as a plunger motor. The pump 1 and the motor 2 form a closed-loop hydraulic drive circuit through the first and second main oil passages L1 and L2.
The output shaft of the motor 2 is equipped with a motor rotation speed sensor 3 for detecting the rotation speed of the motor 2.
The motor 2 may be used to drive the wheels of the walking device. The output shaft of the motor 2 drives the wheels 5 through the transfer case 4, as shown for example.
Alternatively, the motor 2 may be used to drive the wheels and working elements of the walking device. Alternatively, the motor 2 may be used only to drive working elements of various devices. For ease of understanding, the following detailed description with respect to the drawings is given by way of example only of a motor 2 driving a wheel of a vehicle.
The first and second main oil passages L1, L2 are respectively provided with first and second pressure sensors 6, 7 for detecting hydraulic oil pressures in the first and second main oil passages L1, L2.
Further, a crossover oil passage L3 is connected between the first and second main oil passages L1, L2, and a first main oil passage L1 is connected to a crossover oil passage L3 at one end thereof, and a second main oil passage L2 is connected to the other end thereof. The cross-over oil passage L3 has a first brake switch valve 8 in a first side portion and a second brake switch valve 9 in a second side portion, which are normally closed and opened when receiving a signal.
A relief oil passage L4 is connected to a middle portion of the crossover oil passage L3 between the first and second side portions, and the proportional relief valve 10 is disposed in the relief oil passage L4. The relief oil passage L4 has a first end connected to the middle of the crossover oil passage L3 and a second end leading to the oil tank 11.
Further, the hydrostatic drive system includes a replenishment oil pump (not shown) connected to the first and second main oil passages L1, L2 for replenishing oil in the first and second main oil passages L1, L2.
The hydrostatic drive system in fig. 1 is equipped with corresponding controllers, which are connected to a pump 1, a motor 2, a motor speed sensor 3, first and second pressure sensors 6, 7, brake switching valves 8, 9, and a relief valve 10.
As shown in fig. 2, the controller includes a speed controller 12 and a drag torque controller 13. Speed controller 12 receives a speed command input 14. The speed command input 14 is from the driver, operator, or is automatically generated by the controller of the vehicle or device. The speed controller 12 also receives a detection value of the motor rotation speed sensor 3. The speed controller 12 is also capable of controlling the displacement of the pump 1 and the displacement of the motor 2, thereby controlling the output torque of the motor 2.
The drag torque controller 13 receives the detection values from the first and second pressure sensors 6, 7, and information from the speed controller 12, particularly displacement information for controlling the pump 1 and the motor 2. The drag torque controller 13 can also control the operations (valve positions) of the brake switch valves 8 and 9 and the relief valve 10.
The hydrostatic drive system of fig. 1, 2 is capable of performing a hydrostatic braking operation. During hydrostatic braking, the speed controller 12 reduces the displacement of the pump 1 to slow the vehicle.
When the vehicle is in a normal forward running state, the first main oil passage L1 is assumed to be on the high pressure side, i.e., the pump output side, and the second main oil passage L2 is assumed to be on the low pressure side, i.e., the pump intake side. The drag torque controller 13 monitors and compares the pressure values of the pressure sensors 6 and 7 in real time; when the value of the sensor 6 is smaller than the value of the sensor 7, such as in a downhill condition (the hydrostatic drive system performs hydrostatic braking), the drag torque controller 13 outputs an on signal to the second brake switch valve 9 to open the second brake switch valve 9, while the first brake switch valve 8 remains closed. At the same time, the drag torque controller 13 calculates an allowable pump intake side pressure from the power source allowable drag torque, the pump output side pressure, and the current pump displacement. The drag torque controller 13 determines an electrical signal for the proportional relief valve 10 based on the allowable pump suction side pressure, which determines the cracking pressure of the proportional relief valve 10. The drag torque controller 13 sends this electrical signal to the proportional relief valve 10. When the pump suction side pressure reaches this opening pressure, the proportional relief valve 10 opens, and a part of the hydraulic oil in the second main oil passage L2 flows into the tank 11 through the second side portion of the crossover oil passage L3 (via the second brake switch valve 9) and the relief oil passage L4 (via the proportional relief valve 10), thereby limiting the pump suction side pressure to not higher than the allowable pump suction side pressure.
When the vehicle is in a normal reverse traveling state, the second main oil passage L2 is on the high-pressure side, i.e., the pump output side, and the first main oil passage L1 is on the low-pressure side, i.e., the pump intake side. The drag torque controller 13 monitors and compares the pressure values of the pressure sensors 6 and 7 in real time; when the value of the sensor 7 is smaller than the value of the sensor 6, such as in a downhill condition (the hydrostatic drive system performs hydrostatic braking), the drag torque controller 13 outputs an on signal to the first brake switch valve 8 to open the first brake switch valve 8, while the second brake switch valve 9 remains closed. At the same time, the drag torque controller 13 calculates the allowable pump suction side pressure. The drag torque controller 13 determines an electrical signal corresponding to the opening pressure of the proportional relief valve 10 based on the allowable pump suction side pressure. The drag torque controller 13 sends this electrical signal to the proportional relief valve 10. When the pump suction side pressure reaches this opening pressure, the proportional relief valve 10 opens, and a part of the hydraulic oil in the first main oil passage L1 flows into the tank 11 through the first side portion of the crossover oil passage L3 (via the first brake switch valve 8) and the relief oil passage L4 (via the proportional relief valve 10), thereby limiting the pump suction side pressure to not higher than the allowable pump suction side pressure.
The embodiments shown in fig. 1 and 2 are suitable for use in systems with high overflow heat generation and high hydrostatic braking capacity.
Fig. 3 shows a hydrostatic drive system according to another possible embodiment of the present application, which differs from the hydrostatic drive systems of fig. 1 and 2 in that the second end of the return line L4 is not connected to the oil tank, but to the return line L5. The return oil passage L5 has one end connected to the first main oil passage L1 and the other end connected to the second main oil passage L2. The return oil path L5 has a first check valve 15 provided in a first side portion and a second check valve 16 provided in a second side portion. A second end of the relief oil passage L4 is connected to a middle portion of the return oil passage L5 between the first and second side portions. The first and second check valves 15, 16 are oppositely oriented and oriented to allow the hydraulic oil to flow from the intermediate portion of the return oil passage L5 into the first and second main oil passages L1, L2, and not to flow from the first and second main oil passages L1, L2 into the intermediate portion of the return oil passage L5.
Other aspects of the hydrostatic drive system of fig. 3 are the same as those of fig. 1 and 2, and will not be described again.
With the hydrostatic drive system shown in fig. 3, when the vehicle is in a normal forward running state, it is assumed that the first main oil passage L1 is on the high pressure side, i.e., the pump output side, and the second main oil passage L2 is on the low pressure side, i.e., the pump intake side. When the value of the sensor 6 is smaller than the value of the sensor 7, the second brake switching valve 9 is opened while the first brake switching valve 8 is kept closed. At the same time, the drag torque controller (not shown in FIG. 3, described above with reference to FIG. 2) calculates the allowable pump suction side pressure. The drag torque controller determines the electrical signal of the proportional relief valve 10 corresponding to the opening pressure of the proportional relief valve 10 based on the allowable pump suction side pressure. The drag torque controller sends this electrical signal to the proportional relief valve 10. When the pump suction side pressure reaches this opening pressure, the proportional relief valve 10 opens, and a part of the hydraulic oil in the second main oil passage L2 flows into the first main oil passage L1 through the second side portion of the crossover oil passage L3 (via the second brake switch valve 9), the relief oil passage L4 (via the proportional relief valve 10), and the first side portion of the return oil passage L5 (via the first check valve 15), thereby restricting the pump suction side pressure to not higher than the allowable pump suction side pressure.
Similarly, when the vehicle is in a normal reverse running state, the first brake switch valve 8 is opened, and the second brake switch valve 9 is kept closed. When the pump suction side pressure reaches the opening pressure of the proportional relief valve 10, the proportional relief valve 10 opens, and a part of the hydraulic oil in the first main oil passage L1 flows into the second main oil passage L2 through the first side portion of the crossover oil passage L3 (via the first brake switch valve 8), the relief oil passage L4 (via the proportional relief valve 10), and the second side portion of the return oil passage L5 (via the second check valve 16), thereby restricting the pump suction side pressure to not higher than the allowable pump suction side pressure.
The hydrostatic drive system of FIG. 3 is suitable for systems with low flooding heat and low hydrostatic braking capacity.
A hydrostatic drive system according to a further possible embodiment of the present application is shown in fig. 4, which can be regarded as a combination of the hydrostatic drive system of fig. 1, 2 and the hydrostatic drive system of fig. 3. A return oil passage L5 is provided, and a first main oil passage L1 is connected to one end of a return oil passage L5, and a second main oil passage L2 is connected to the other end thereof. The return oil path L5 has a first check valve 15 provided in a first side portion and a second check valve 16 provided in a second side portion. The first and second check valves 15, 16 are oppositely oriented. A second end of the relief oil passage L4 is connected to a middle portion of the return oil passage L5 between the first and second side portions. Further, the additional return oil passage L6 leads from an intermediate portion of the return oil passage L5 to the oil tank 11. A normally closed return flow switching valve 17 is provided in the additional return flow path L6, and the return flow switching valve 17 is controlled by a drag torque controller (not shown in fig. 4, described above with reference to fig. 2). The drag torque controller may selectively open and close the return on-off valve 17 based on actual conditions to perform either similar operations to the embodiment of fig. 1 and 2 or the embodiment of fig. 3 when the pump intake pressure is higher than the pump output pressure.
The embodiment in fig. 4 is suitable for systems with various overflow heating values and hydrostatic braking capacity.
As described above, according to the hydrostatic drive system of the present application, the hydrostatic braking operation can be performed. In the hydrostatic braking process, the pressure on the suction side of the pump can be kept in a safe range by overflowing the hydraulic oil on the suction side of the pump, so that the power source is over-high in rotating speed when being reversely dragged by the pump, and the condition that dragging torque possibly causing flameout or damage is borne is avoided.
In addition, when the hydrostatic drive system brakes, the braking capacity of the power source is fully utilized, and the heat generation of the hydraulic drive system is minimized. In addition, the hydrostatic drive system has large braking torque and is particularly suitable for constant-speed working conditions.
In addition, the hydrostatic drive system is provided with two oil return modes which can be selected from one or the combination of the two oil return modes, so that different braking capacity requirements can be met.
Although the present application has been described herein with reference to specific exemplary embodiments, the scope of the present application is not intended to be limited to the details shown. Various modifications may be made to these details without departing from the underlying principles of the application.
Claims (10)
1. A hydrostatic drive system, comprising:
a closed variable displacement pump (1); and
the variable displacement pump comprises a variable displacement motor (2) and a closed type variable displacement pump (1), wherein a closed-loop hydraulic drive circuit is formed by a first main oil path and a second main oil path, and when the closed type variable displacement pump operates, one of the first main oil path and the second main oil path is a pump output side oil path, and the other main oil path is a pump suction side oil path;
characterized in that the hydrostatic drive system further comprises:
a crossover oil passage (L3) that is connected between the first and second main oil passages and is equipped with normally closed first and second brake switch valves;
a relief oil passage (L4) connected to an intermediate portion of the crossover oil passage (L3) between the first and second brake switching valves, a proportional relief valve (10) being disposed in the relief oil passage (L4); and
a drag torque controller (13) configured to control operation of the first and second brake switch valves and the proportional relief valve (10).
2. The hydrostatic drive system of claim 1, characterized in that the drag torque controller (13) is configured to determine an electrical signal to the proportional relief valve (10) based on the allowable pump suction side pressure, the electrical signal determining the cracking pressure of the proportional relief valve (10).
3. The hydrostatic drive system as claimed in claim 1, characterized in that the relief oil line (L4) leads to an oil tank (11).
4. The hydrostatic drive system of claim 3, wherein said drag torque controller (13) is configured to communicate said spill oil path (L4) with the pump intake side oil path while maintaining said spill oil path (L4) disconnected from the pump output side oil path when the pressure of the pump intake side oil path is higher than the pressure of the pump output side oil path.
5. The hydrostatic drive system of claim 1, further comprising a return line (L5), the return line (L5) having first and second check valves therein, the return line (L4) opening into an intermediate portion of the return line (L5) between the first and second check valves.
6. The hydrostatic drive system of claim 5, further comprising an additional return line (L6), the additional return line (L6) being connected to a middle portion of the return line (L5) between the first and second check valves and leading to the oil tank (11), the additional return line (L6) being provided with a normally closed return on-off valve (17).
7. The hydrostatic drive system of claim 6, characterized in that said drag torque controller (13) is configured to connect said relief oil circuit (L4) to the pump intake side oil circuit, to keep said relief oil circuit (L4) disconnected from the pump output side oil circuit, and to open said return switch valve (17) when the pressure of the pump intake side oil circuit is higher than the pressure of the pump output side oil circuit.
8. The hydrostatic drive system of any of claims 1-7, further comprising a speed controller (12) configured to control the displacement of the closed variable pump (1) and the variable motor (2).
9. The hydrostatic drive system of claim 8, wherein the speed controller (12) is configured to reduce the displacement of the closed variable displacement pump (1) when the hydrostatic drive system performs a hydrostatic braking operation.
10. The hydrostatic drive system according to any of claims 1 to 7, characterized in that the opening pressure of the proportional relief valve (10) is set to be not higher than an allowable pump suction side pressure, which depends on a drag torque that a power source driving the closed variable pump (1) can withstand.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120368512.9U CN215257684U (en) | 2021-02-08 | 2021-02-08 | Hydrostatic drive system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120368512.9U CN215257684U (en) | 2021-02-08 | 2021-02-08 | Hydrostatic drive system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN215257684U true CN215257684U (en) | 2021-12-21 |
Family
ID=79501677
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120368512.9U Active CN215257684U (en) | 2021-02-08 | 2021-02-08 | Hydrostatic drive system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN215257684U (en) |
-
2021
- 2021-02-08 CN CN202120368512.9U patent/CN215257684U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8261544B2 (en) | Control system and method for braking a hydrostatic drive machine | |
| US8201404B2 (en) | Motor control device for construction machinery | |
| US7628240B2 (en) | Fluid transmission with improved traction control | |
| CN110657234B (en) | Hydrostatic travel drive and method for controlling the hydrostatic travel drive | |
| AU2021311138B2 (en) | Hydraulic retarding control system | |
| CN101535687B (en) | Travel control device for hydraulic traveling vehicle | |
| US20220307595A1 (en) | Hydraulic circuit architecture with enhanced operation efficency | |
| CN114475669B (en) | Automatic variable drive control system of monorail crane locomotive | |
| CN215257684U (en) | Hydrostatic drive system | |
| CN104831774A (en) | Loader walking and braking energy recovery auxiliary driving device and control method | |
| CN114909452A (en) | Hydrostatic constant-speed driving system | |
| CN112238845A (en) | Brake valve bank for hydrostatic transmission system of railway engineering machinery vehicle | |
| CN214366946U (en) | Closed hydraulic system and vehicle | |
| CN113280011B (en) | Hydrostatic drive system for vehicle and control method thereof | |
| JP2690353B2 (en) | Make-up device for hydraulic circuit using load sensing system | |
| CN113280010B (en) | Static pressure driving system and method for improving acceleration and deceleration performance of vehicle | |
| CN115352419B (en) | Hydraulic control system and method for snow pressing vehicle capable of recycling braking energy | |
| CN211116872U (en) | Novel hydraulic traveling reverse drive control system | |
| CN213705407U (en) | Brake valve bank for hydrostatic transmission system of railway engineering machinery vehicle | |
| CN201580336U (en) | Control device for controlling driving smoothness of hydraulic drive vehicle | |
| CN205951716U (en) | Novel ensilage machine hydraulic pressure traveling system | |
| JPH04112916A (en) | Method for driving cooling fan | |
| JP5947029B2 (en) | Hydraulic drive vehicle | |
| CN115306841A (en) | High-pressure cycloid rotor type high-viscosity oil retarder electric control system and control method | |
| CN110805581A (en) | Novel hydraulic traveling reverse drive control system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |