JP4386476B2 - Hydrostatic drive system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a hydrostatisches antriebs system, which has a pump and a plurality of actuators, and the pump and the container are provided by a directional control valve in which the one actuator can be operated with a plurality of control pressures. said pump and capable of communicating alternately with positive load and the negative can control the motion of the load, and said further actuator is operable directional control valve in a plurality of control pressure in said one actuator and the container and alternately capable of communicating, and making it possible to control the movement of the positive load and the negative load in the further actuator continues the said container (3) from the respective directional control valves be arranged bias valve outlet conduit (11), said bias valve is being loaded with spring force in the closing direction, at the outlet conduit constantly under pressure, wherein it exceeds the adjusted pressure vessel In Being adapted to open bought, the plurality of conduits following the plurality of actuators from each directional control valve, each one being connected to said outlet conduit by a bypass conduit, said each bypass conduit, each It relates to a type in which each one check valve opening towards the conduit is arranged .
[0002]
[Prior art]
Such a drive system is used for a work machine, for example, a dredger. The directional control valve controls the movement of positive load or negative load in each actuator according to the control pressure. In this case, positive load is understood as a load acting in the opposite direction to the movement regulated by the direction control valve in the actuator. Correspondingly, a negative load means a load that supports the movement adjusted by the actuator by means of a directional control valve. Thus, for example, a hydraulic cylinder that operates the load in the vertical direction receives a positive load when lifting the load. When unloading, the actuator is under a negative load.
[0003]
When operating a negative load, an operating condition may occur where the pressure medium flows out of the actuator outlet side faster than provided by the pump on the actuator supply side. This can lead to underfilling on the supply side, which can cause cavitation. In order to avoid this underfill on the supply side of the actuator, a spring-elastically loaded bias valve is placed in the outlet conduit following the container, and the pressure in the outlet conduit is adjusted in the bias valve by this bias valve. It is known that the value is usually boosted to about 3-4 bar. In this case, the pressurized pressure medium in the outlet conduit can be provided to the supply side of the actuator. For this purpose, it is known to communicate the outlet conduit with a conveying conduit connected to the supply side of the actuator by means of a bypass line in which a check valve opening towards the supply side of the actuator is arranged. . Thus, when operating the directional control valve, the pressure medium flowing into the outlet conduit from the outlet side of the cylinder is caused by the bias valve in an operating state where the actuator receives a negative load, for example, a load lowered by the hydraulic cylinder. It will be boosted and flow into the actuator supply through the bypass and open check valve. This amplified flow flowing from the outlet conduit to the supply side of the actuator can reduce the proportion of the supply flow that must be supplied by the pump.
[0004]
In a drive train with several actuators, the actuators may have different magnitude demands for the amplified flow. If most of the pressure medium stream entering the supply side is withdrawn from the biased return stream in the outlet conduit and only a part of the supply stream needs to be supplied by the pump, a dredge, for example a jib Can reduce energy consumption when falling. In order to overcome the conduit resistance under such a large amplified flow and avoid underfill on the supply side, an actuator with a large amplified flow already has a relatively large bias pressure. It is known to provide another bias valve connected in series with the bias valve.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a hydrostatic drive system in which the bias pressure of the outlet conduit is variable and the structure cost is relatively low.
[0006]
[Means for Solving the Problems]
In the configuration of the present invention to solve the above problems, in the directional control valve belonging to the actuator to be the operation, prior Symbol control pressure for controlling the movement of the negative load of the actuator to be the working When there exist in addition to additionally bias to the bias valve, greater amplification flow being adapted to give rise to, the amplification flow Kiba bypass conduit before belonging to actuator to be the operation from the outlet conduit and Previous through Kigyaku stop valve, and flows into the front Kishirube tube of the supply side of the actuator to be the working, the control pressure is guided in the control pressure introducing tube, the control pressure A conduit operates the directional control valve belonging to the actuator to be actuated with the control pressure to control the negative load movement of the actuator to be actuated, and the bias valve to a higher bias At least one to switch to pressure And it was as functionally connected shuttle valve.
[0007]
The outlet conduit is adjusted by a bias valve to a value corresponding to a normal bias value of 3-4 bar. When the directional control valve is operated with a control pressure at which the directional control valve receives a negative load, the bias pressure of the bias valve is increased. Thereby, the bias valve can be switched to a higher bias pressure in accordance with the control vibration for the negative load. By doing so, the bias pressure of the bias valve is adapted to each amplified flow of the actuator. As a result, the occurrence of insufficient filling can be effectively prevented on the supply side of the actuator even in an operating state where a large amplified flow is required. By switching the bias valve to a higher bias value when operating an actuator having a large amplified flow, only one bias valve is required according to the present invention, thereby reducing the construction cost of the drive train. Further, by omitting other bias valves, the structure volume and manufacturing cost of the drive system can be reduced.
[0008]
In the configuration of the present invention, when there is a control pressure for controlling the movement of the negative load, the working surface acting in the closing direction of the bias valve can be additionally loaded with pressure. By additionally applying pressure to the bias valve, the bias pressure of the bias valve can be easily increased, thereby allowing the bias to be applied at a higher value on the outlet side.
[0009]
In another configuration of the invention, the bias valve can be loaded with an additional force in the closing direction if there is a control pressure to control the movement of the negative load. With this configuration, it is possible to switch the bias valve to a higher bias pressure.
[0010]
It is reasonable for the control pressure that controls the movement of the negative load to load a mechanical component, in particular a piston, that produces a force acting in the closing direction of the bias valve. In order to increase the bias pressure, an additional force acting in the closing direction of the bias valve is produced by the piston in response to the control pressure.
[0011]
In addition, a pressure medium conduit communicating with the working surface or mechanical component acting in the closing direction of the bias valve in the first switching position is in communication with the vessel, and a control pressure in communication with the pump is in the second switching position. It is advantageous if present in the switching valve. In this case, in order to increase the bias value of the bias valve, a working surface acting in the closing direction of the bias valve or a piston producing a force acting in the closing direction of the bias valve is provided in the transport conduit of the pump, in particular the feed pump of the drive train. It is in communication with a connected pressure medium conduit. Thereby, the additional load of the bias valve is controlled by the switching valve which can be operated by the control pressure for the negative load of the directional control valve. By this biasing operation of the bias valve, the bias value of the bias valve can be increased correspondingly even at a moderate control pressure.
[0012]
It is reasonable that the switching valve can be loaded with a spring force toward the first switching position and can be loaded with a control pressure toward the second switching position. By doing so, it is particularly reasonable that the switching valve, which makes it easy to switch the bias valve to an increased bias value when controlling a negative load, is formed as a switching valve that throttles in an intermediate position It is. Thereby, the pressure present at the intermediate position depends on the magnitude of the control signal of the directional control valve. Thereby, the bias value of the bias valve is increased according to the magnitude of the control signal of the direction control valve.
[0013]
A directional control valve is operable with each one hydraulic control pressure present in the control pressure conduit, and a control pressure conduit having a control pressure for controlling the movement of the negative load is present in the bias valve. It is particularly advantageous to communicate with a working surface or mechanical component or a switching valve that acts in the closing direction. By directly loading the working surface on which the control pressure conduit acts in the closing direction of the bias valve, the bias valve can be easily switched to a higher bias pressure by the hydraulic control pressure. Furthermore, the control pressure can directly load the piston to increase the bias. In addition, a bias operation by a switching valve is possible.
[0014]
In a preferred configuration of the invention, the bias valve is formed as a check valve that opens against the spring force. The check valve is a simple valve member that can be incorporated into the outlet conduit of the drive train.
[0015]
It is particularly advantageous that the check valve has a piston operatively connected to the spring side, which is in communication with a pressure medium conduit connected to a control pressure conduit or a switching valve. A piston in communication with the spring side of the check valve provides a simple way of creating a force acting in the closing direction of the bias valve. In this case, the check valve can be loaded directly by the hydraulic control pressure of the bias valve. Furthermore, the bias operation of the bias valve by the switching valve is possible.
[0016]
Another preferred configuration of the invention is formed as a pressure limiting valve in which the bias valve opens toward the container against the spring force. The pressure limiting valve is a simple and inexpensive valve member that can bias the outlet conduit of the drive train.
[0017]
In this case, it is particularly advantageous that the working surface acting in the closing direction of the pressure limiting valve is in communication with a control pressure conduit or a pressure medium conduit connected to the switching valve. By doing so, the pressure limiting valve is loaded in the closing direction by the control pressure of the direct direction control valve, or by the pump pressure present in the pressure medium conduit in the biasing operation by the switching valve.
[0018]
In addition, a throttle is arranged in the control pressure conduit or pressure medium conduit in communication with the working surface acting in the closing direction of the pressure limiting valve, downstream of the throttle and with the outlet conduit downstream of the pressure limiting valve. It is advantageous if a branch conduit in communication is provided and another throttle is arranged in the branch conduit. The pressure acting in the closing direction of the pressure limiting valve can be adjusted by a throttle. As soon as there is no control pressure in the directional control valve and therefore an increased bias value for the pressure control valve is not required, the throttle located in the branch conduit causes the pressure present in the pressure limiting valve to be controlled. Dissolved in the conduit or pressure medium conduit.
[0019]
In a drive train with several hydraulically operable directional control valves, the control pressure conduit is operatively connected to at least one shuttle valve and the outlet of the shuttle valve is connected to the control pressure conduit following the bias or switching valve. It is particularly advantageous. The shuttle valve makes it possible to easily connect several control pressure conduits to the control pressure conduit following the switching or bias valve. This allows the outlet conduit bias to be easily adapted to the various amplified flows of the actuator in a drive train having several actuators.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0021]
FIG. 1 shows a circuit diagram of a hydrostatic pressure drive system of the present invention having a pump 1 driven by a drive motor 2 and having a constant or variable discharge amount. The pump 1 sucks the pressure medium from the container 3 and discharges it to the supply conduit 4. Supply conduits 4a and 4b branch from supply conduit 4 and continue to directional control valves 5a and 5b. The direction control valves 5a and 5b are in communication with the actuators 8a and 8b, which in this embodiment are formed as cylinders, by means of two conduits 6a and 7a or 6b and 7b. However, the present invention can also be applied to rotary actuators. Two outlet conduits 9a and 10a or 9b and 10b respectively follow the outlet conduit 11 from the direction control valves 8a and 8b, and the outlet conduit 11 communicates with the container 3. A bias valve 12 formed as a check valve 25 is arranged in the outlet conduit 11. The bias valve 12 is spring loaded in the closing direction and opens towards the container 3.
[0022]
The conduits 6a and 7a of the directional control valve 5a are connected to the outlet branch conduits 9a and 10a by one bypass conduit 13, 14 respectively. One check valve 13a and 14a is arranged in each of the bypass conduits 13 and 14. Check valves 13a and 14a open towards conduits 7a and 6a. With this configuration, in the directional control valve 5b, the conduits 6b and 7b are connected to the outlet branch conduits 9b and 10b by the two bypass conduits 15 and 16 and the check valves 15b and 16b.
[0023]
The direction control valve 5a has control valves 17a and 18a acting in opposite directions, followed by control pressure conduits 17b and 18b. When the control pressures 17 and 18 are present in the control pressure conduits 17b and 18b, the directional control valve 5a can be operated to the corresponding switching position and the supply branch conduit 4a and the outlet branch conduit 9a or 10a are connected to each of the conduits 6a and 7a. Communicate alternately with one. The direction control valve 5b is present in the control pressure conduits 19b and 20b and is operable by the control pressures 19 and 20 loading the control surfaces 19a and 20a. The control pressure conduits 18b and 19b are connected to the inlet side of the shuttle valve 21, and another control pressure conduit 22 is connected to the outlet thereof. Control pressure conduit 22 is operatively coupled to piston 23. The piston 23 generates an additional force at the check valve 25 that acts in the closing direction of the check valve 25.
[0024]
When the directional control valve 5b is operated with the control pressure 19 guided in the control pressure conduit 19b, the directional control valve 5b enters the switching position shown on the left in the drawing. In this switching position, the pressure medium flows from the supply conduit 4, the supply branch conduit 4b and the directional control valve 5b to the conduit 7b and thus to the supply side of the actuator 8b. The outlet side of the actuator 8b communicates with the outlet conduit 11 via the conduit 6b, the direction control valve 5b and the outlet branch conduit 9b. The pressure in the outlet conduit 11 is increased in response to the spring bias of the check valve 25. The pressure medium pressurized in the outlet conduit 11 and the outlet branch conduit 10b flows to the bypass conduit 15, the check valve 15a and the conduit 7b, and thus to the supply side of the actuator 8b. When the actuator operates a negative load, for example a load that pulls the piston rod of the cylinder, a bias in the return flow on the supply side of the actuator prevents underfill and thus cavitation. The amplified flow flowing from the outlet side to the supply side can reduce the proportion of the supply flow supplied by the pump, thereby resulting in less energy consumption.
[0025]
In order to prevent insufficient filling on the supply side even when the amplified flow is large, the check valve 25 is applied by the piston 23 loaded with the control pressure 19 existing in the control pressure conduit 19b via the control pressure conduit 22 and the shuttle valve 21. Can be additionally biased. When the directional control valve 5b is operated by the control pressure 19 in the control pressure conduit 19b, the piston 23 generates an additional force acting in the closing direction of the bias valve 12. Thereby, the check valve 25 is switched to a higher bias pressure.
[0026]
When the directional control valve 5a is operated to the switching position shown on the right side of the drawing by the control pressure 18 in the control pressure conduit 18b to control the movement of the negative load, the bias pressure of the check valve 12 is similarly increased. . Such a negative load is a dredge jib operated by an actuator 8a formed as a cylinder, for example. In the above switching position of the directional control valve 5a, i.e. when the jib is lowered, a larger amplified flow into the additional bias of the outlet conduit 11 flows from the outlet conduit 11 into the bypass conduit 14 and the check valve 14a. 6a and thus can flow to the supply side of the actuator 8a. By doing so, the discharge flow supplied from the pump 1 can be reduced.
[0027]
In FIG. 2, the bias valve 12 is formed as a pressure limiting valve 30 loaded with a spring force in the closing direction. The spring side of the pressure limiting valve 30 is connected to the control pressure conduit 22 and can therefore be additionally loaded by the control pressure in the control pressure conduit 22. A throttle 31 is disposed in the control pressure conduit 22. Downstream of the throttle 31, the control pressure conduit 22 is connected to the outlet conduit 11 downstream of the bias valve 12 by a branch conduit 32 and a throttle 33 disposed in the branch conduit 32. When the directional control valve 5a is operated with the control pressure 18 in the control pressure conduit 18b or when the directional control valve 5 is operated with the control pressure 19 in the control pressure conduit 19b, each control pressure in the control pressure conduit 18b or 19b is It exists on the spring side of the pressure limiting valve 30 via the shuttle valve 21 and the control pressure conduit 22. Thereby, the additional bias of the pressure limiting valve 30 is performed by the control pressure of the operated directional control valves 5a and 6a. The magnitude of the control pressure and thus the additional bias of the pressure limiting valve 30 can be influenced by the throttle 31. When the control pressure 18 or 19 is decreased, the control pressure in the control pressure conduit 22 is reduced by the throttle 33 and the branch conduit 32, so that the normal bias is adjusted in the pressure control valve 30.
[0028]
3 and 4 show a bias valve that can be biased by a control pressure 18 or 19 present in the control pressure conduit 22. The bias valve 12 formed as a check valve 25 according to FIG. 3 has a piston 23. The piston 23 is connected to the pressure medium conduit 40. A switching valve 41 formed as a directional control valve is arranged in the pressure medium conduit 40. The switching valve causes the pressure medium conduit 40 to communicate with the conduit 42 following the container 3 in the first switching position 41a. In the second switching position 41b, the pressure medium conduit 40 can be connected to a supply conduit 43 of a pump 44, for example a feed pump of a hydrostatic drive system. However, it is also possible to connect the supply conduit 43 to the supply conduit 4 of the pump 1. The switching valve 41 can be loaded by a spring toward the first switching position, and can be loaded by the control pressure 18 or 19 existing in the control pressure conduit 22 toward the second switching position. When the direction control valve 5a, 5b is operated by the control pressure 17, 20 in the control pressure conduit 17b or 20b, the switching valve 41 is in the illustrated switching position. The pressure in the outlet conduit 11 is increased in response to the spring bias of the bias valve 12. As soon as the control pressure 18 or 19 is present in the control pressure conduit 18b or 19b, the control pressure proceeds to the control pressure conduit 22 via the shuttle valve 21 and loads the switching valve 41 into the switching position 41b. In this switching position, the pressure medium conduit 40 is connected to the supply conduit 43 of the pump 44. Thereby, the piston 23 of the check valve 25 is loaded by the discharge pressure of the pump 44 and generates a force acting in the closing direction of the check valve 25.
[0029]
When the bias valve 12 is formed as the pressure limiting valve 30 according to FIG. 4, a throttle 45 is provided in the pressure medium conduit 40. A branch conduit 46 communicating with the outlet conduit 11 is branched downstream of the throttle. Another throttle 47 is arranged in the branch conduit 46. The discharge pressure of the pump 44 existing on the spring side acting in the closing direction of the pressure limiting valve 30 at the second switching position 41 b of the switching valve 41 can be adjusted by the throttles 45 and 46.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a hydrostatic pressure drive system of the present invention having a bias valve that can be loaded with a direct control pressure.
FIG. 2 is a diagram showing another configuration according to FIG. 1;
FIG. 3 is a diagram showing a drive system having a bias valve.
FIG. 4 is a diagram showing another configuration according to FIG. 3;
[Explanation of symbols]
1 pump, 3 container, 5a directional control valve, 5b directional control valve, 11 outlet conduit, 12 bias valve, 17 control pressure, 18 control pressure, 18b control pressure conduit, 19 control pressure, 19b control pressure conduit, 20 control pressure, 21 Shuttle valve, 22 Control pressure conduit, 23 Piston, 25 Check valve, 30 Pressure limit valve, 31 Restriction, 32 Branch conduit, 33 Restriction, 40 Pressure medium conduit, 41 Switching valve, 41a Switching position, 41b Switching position, 45 Restrictor, 46 branch conduit, 47 restrictor

Claims (14)

A hydrostatic pressure drive system having a pump (1) and a plurality of actuators (8a; 8b), and a direction in which the actuator (8a) can be operated with a plurality of control pressures (17, 18). The control valve (5a) can alternately communicate with the pump (1) and the container (3), can control the movement of positive and negative loads in the actuator (8a), and the actuator (8b) can be alternately communicated with the pump (1) and the container (3) by a directional control valve (5b) that can be operated with a plurality of control pressures (19, 20). And negative load movement can be controlled, and the bias valve (12) in each outlet control valve (5a; 5b) into the outlet conduit (11) following the container (3). And the bias valve (12) is closed The outlet conduit (11) is constantly placed under pressure and opens toward the container (3) when the regulated pressure is exceeded, and each of the directional control valves A plurality of conduits (6a, 7a; 6b, 7b) from (5a; 5b) to the plurality of actuators (8a; 8b) are connected to the outlet conduit by a single bypass conduit (13, 14; 15, 16). (11), and each bypass conduit (13, 14; 15, 16) has one check valve (13a, 13a, 6b, 7b) that opens toward each conduit (6a, 7a; 6b, 7b). 14a; 15a, 16a), in the type in which the directional control valve (5a; 5b) belonging to the actuator (8a; 8b) to be operated is connected to the actuator (8a; 8b) to be operated. before for controlling the movement of a negative load) Control pressure; If (18 19) are present, by adding additional bias to the bias valve (12) being adapted to give rise to large amplification flow, the amplified flow from said outlet conduit (11) It said actuation to be actuators; Fang bypass conduit before belonging to (8a 8b) (1 4; 1 5) and before Kigyaku valve; through (1 4a 15 a), actuator should the actuation (8a; supply side of the front Kishirube tube 8b) (6a; 7 b) is adapted to flow into the control pressure (18; 19), each control conduits (18b; is guided within 19b) The control pressure conduit (18b; 19b) is the actuator to be operated at the control pressure (18; 19) for controlling the movement of the negative load of the actuator (8a, 8b) to be operated. In order to operate the directional control valves (5a; 5b) belonging to (8a, 8b), and And a hydrostatic drive system characterized in that it is operatively coupled to at least one shuttle valve (21) to switch the bias valve (12) to a higher bias pressure . Before SL control pressure for controlling the movement of said negative load; If (18 19) is present, working surface which acts in the closing direction of the bias valve (12) can be loaded additionally to the pressure, The hydrostatic drive system according to claim 1. Before SL control pressure for controlling the movement of said negative load; If (18 19) is present, the bias valve (12) can be loaded with additional force in the closing direction, the static of claim 1, wherein Hydraulic drive system. The negative front Symbol control pressure for controlling the movement of the load (18; 19), a mechanical component to produce a force acting in the closing direction of the bias valve (12), in particular the load piston (23), The hydrostatic pressure drive system according to claim 3. In the first switching position (41a) the pressure medium conduit (40) communicating with the working surface or the mechanical component (23) acting in the closing direction of the bias valve (12) is connected to the container (3). present in; (19 18) is switched valve (41) and is communicated, communicates with a second switching position (41b) in said pump, before Symbol control pressure for controlling the movement of said negative load The hydrostatic pressure drive system according to any one of claims 1 to 4. The switching valve (41) can be loaded with a spring force toward the first switching position (41a), and controls the movement of the negative load toward the second switching position (41b). before SL control pressure; it can be loaded with (18 19), according to claim 5 hydrostatic drive system according.   The hydrostatic drive system according to claim 5 or 6, wherein the switching valve (41) is formed as a switching valve that throttles at an intermediate position. Each directional control valves (5a; 5b) has the respective control pressure conduit (17b, 18b; 19b, 20b ) before SL control pressure present in the (17, 18; 19, 20) by being operable the negative load before Symbol control pressure for controlling the movement of; the control pressure conduit (18 19) is present (18b; 19b) acts in the closing direction of the bias valve (12) The hydrostatic drive system according to any one of claims 1 to 7, wherein the hydrostatic drive system is in communication with the working surface, the mechanical component or the switching valve (41).   9. The hydrostatic drive system according to claim 1, wherein the bias valve is formed as a check valve that opens against a spring force. The check valve (25) spring-side and has a piston (23) which is operatively connected, the piston (23) is directional control valve to be the operation; the control pressure conduit (5a 5b) ( The hydrostatic drive system according to claim 9, wherein the hydrostatic drive system is in communication with the pressure medium conduit (40) connected to 18b; 19b) or the switching valve (41).   9. Hydrostatic drive according to any one of claims 1 to 8, wherein the bias valve (12) is formed as a pressure limiting valve (30) that opens towards the container (3) against spring force. system. Said working surface which acts in the closing direction of the pressure limiting valve (30) is, the control pressure conduit; communicates with (18b 19b) or the pressure medium conduit (40) connected to said switching valve (41) The hydrostatic pressure drive system according to claim 11. The pressure limiting valve (30) the working surface and the communication with the control pressure conduit which acts in the closing direction of (18b; 19b) or the pressure medium conduit (40) within the aperture (31; 45) is arranged And a branch conduit (32; 46) communicating with the outlet conduit (11) downstream of the pressure limiting valve (30) is provided downstream of the throttle (31; 45), 13. Hydrostatic drive system according to claim 11 or 12, wherein another throttle (33; 47) is arranged in the branch conduit (32; 46). 14. The hydrostatic drive system according to any one of claims 1 to 13, wherein each directional control valve (5a; 5b) capable of hydraulic operation is provided for controlling the movement of the negative load. the control pressure conduit; (19 18) is present before Symbol control pressure (18b; 19b) are functionally connected at least one shuttle valve (21), the outlet of the shuttle valve (21) is the A hydrostatic pressure drive system connected to a control pressure conduit (22) following the bias valve (12) or the switching valve (41).

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