JPS59121202A - Fluid pressure device - Google Patents

Abstract

PURPOSE:To prevent the generation of thermal shocks by such an arragement that each of flowrate and direction control valves is provided with a pilot passage which is interconnected to a tank passage at the control valve's neutral position and closed at its change-over position. CONSTITUTION:The secondary side of a decompression type pressure compensation valve 102 is connected to the spring chamber of a load sensing valve 163, and the load sensing valve is controlled so that it causes a variable fluid pressure pump 162 to discharge a fluid at such a pressure and flowrate that correspond to the load pressure of an actuator at all times. Each of flow-rate and direction control valves 103-106 is provided with a pilot passage 108 which is interconnected to a tank passage 113 at the control valve's neutral position and is closed at its change-over position. The passage 108 is connected to the secondary side of the pressure compensation valve 102. Consequently, even in a feathering situation, a small amount of fluid is caused to flow through the pilot passage 108 and it prevents the fall of temperature of the flow-rate and direction control valves 103-106.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic device, and particularly to a hydraulic device that can save power and prevent thermal shock.

In general, in earth moving machines such as power shovels, the horsepower required varies widely depending on the type of work, so hydraulic pumps, etc. are driven according to load demands to prevent power loss. It is necessary to save power by doing so.

As a hydraulic device for achieving such power saving, there is a device described in Japanese Patent Application Laid-Open No. 50-51682. This device has a pressure reducing expansion pressure compensating valve interposed in the main flow circuit f+11i in front of the variable orifice of the flow direction control valve, and
．． A pilot line branched from the rear of the variable orifice is communicated with a spring chamber of a decompression expansion pressure compensation valve, and the pilot line is further communicated with a spring chamber of a load sensing valve in a variable displacement hydraulic pump. .

According to this device, it is possible to prevent the pump from discharging an extra flow rate that is not required by the actuator, and also to prevent the generation of extra pressure that is not required by the load, making it possible to save power.

However, it is known that when the above-mentioned device is used in a cold region, there is a drawback that thermal shock is likely to occur. In other words, in the above device, when all the flow rate directional control valves are in the neutral position, the flow rate of the fluid discharged from the hydraulic pump is extremely small, and the pressure is also controlled by the spring of the discharge amount control section of the variable displacement hydraulic pump. The pressure is just enough to push through. In this feathering state (in this case, fluid is not supplied to each flow direction control valve at all, and the flow direction tall valve is cooled by the outside air), on the other hand, the fluid is discharged from the hydraulic pump, The fluid flowing through the load sensing valve and the discharge rate control section is
As mentioned above, it exists, albeit in a small amount, and therefore the temperature of the fluid remains unchanged even in this state. When the flow rate directional control valve is moved to the switching position from this state, a fluid with a higher temperature flows into the cooled flow quenching control valve, and the flow rate directional control valve is rapidly heated. Ru. However, in a flow rate directional control valve, the main body and spool usually have different coefficients of thermal expansion and different ways of transmitting heat from the fluid.
If the whole is heated up rapidly, for example, only the spool expands and it becomes impossible to move the spool, resulting in an undesirable phenomenon that the actuator cannot be operated, that is, a thermal shock.

This invention was made in view of the above (the purpose of this invention is a hydraulic device that can prevent the occurrence of thermal shock as described above, and that can also save power in almost the same way as the above device). Our goal is to provide the following.

The hydraulic device of the present invention that achieves the above object has a discharge amount control section that is
Connect the primary side of the decompression and expansion pressure compensation valve to the discharge path of the variable capacity forming pressure pump that has been obtained.
A flow direction control valve is connected to the next side, and the pressure at the front side of the flow direction control valve 1 is sent to the pilot chamber of the pressure reduction/expansion pressure compensation valve, and the pressure at the rear side is sent to the spring chamber, and further the flow rate direction control valve The valve is provided with a pilot passage that communicates with the tank passage t at its neutral position and is closed at its switching position, and the pilot passage is connected to the secondary side of the pressure reduction expansion pressure compensating valve, and The expansion pressure compensating valve is connected to the pilot chamber of the primary side load sensing valve, and the secondary side is connected to the spring chamber, respectively, and the low k' sensing valve is used to control the discharge amount of the hydraulic pump. be.

In the above device, the load pressure after the flow rate directional control valve is guided to the spring chamber of the decompression and expansion pressure compensation valve, so the secondary side of the decompression and expansion pressure compensation valve is always lower than the load pressure required by the actuator. The fluid pressure is kept high by a pressure corresponding to the spring force. In addition, since the secondary side of this pressure compensation valve is in contact with the spray chamber of the load sensing valve, the load sensing valve always discharges fluid from the variable hydraulic pump at a pressure and flow rate corresponding to the load pressure of the actuator. Control is performed to reduce power consumption. Moreover, the flow rate directional control valve is provided with a pilot passage that communicates with the tank passage in its neutral position and is closed in its switching position, and this pilot passage is connected to the secondary side of the decompression expansion pressure compensation valve. Even in the feathering state, a small amount of fluid flows through this pilot passage, thereby preventing a drop in temperature of the flow direction control valve in the feathering state.

Hereinafter, specific embodiments of the hydraulic device of the present invention will be described in detail with reference to the drawings.

First, a first embodiment of the present invention is shown in FIG. 1. This hydraulic device (100) includes a valve unit (101) for controlling fluid supplied to an actuator (101), and a valve unit (101) for controlling fluid supplied to an actuator.
101) and a pump unit (160) that supplies fluid to the pump.

The above valve unit I-(101,) is a pressure reduction expansion pressure compensation valve (
102), a first flow direction control valve (103), a second flow direction control valve (104), and a third flow direction control valve (105).
) and a fourth flow rate directional control valve (106), these first to fourth flow rate directional control valves (103)
(104), (105), and (106) each have the functions of a directional control valve and a flow rate control valve. And these flow rate directional control valves (103) (104) (11') 5)
(106) has a feedback passage (10
A load detection port (Cdl) capable of detecting the pressure downstream of the flow rate adjustment section (not shown) via 7), and a pilot passage (113) that communicates with a tank passage (113) to be described later when in its neutral position and is closed when it is in its switching position. 108) is provided.

The above vacuum expansion pressure compensation valve (102 function) Secondary port (109
) connects the first to fourth flow rate directional control valves (103) (104) (105) (106) via a line (110).
is connected to each pump port of the decompression expansion pressure compensation valve [1
02)'s primary port ) (111) is the main line (1
12) to the pump unit (160). In addition, each flow rate directional control valve (103) (104) (
105M106) tank port is the tank passage (113
) to the tank (114).

The first to fourth flow rate directional control valves (103) (104)
) (105) (106) The detected pressure at each load pressure detection port ()rdl is determined by the shuttle valve (115) (116) (
117), the maximum pressure is selected by the pressure reducing valve (102) via the throttle (11, 8).
The pressure on the secondary side is guided into the spring chamber and opposed to the pressure on the secondary side guided into the pilot chamber. Therefore, the decompression swelling pressure f# direct valve (10
The pressure at the secondary port (109) of 2) corresponds to the spring force of the pressure compensation valve (102), rather than the maximum load pressure selected by the shuttle valves (115), (116), and (117) as described above. The fluid pressure will be maintained at a higher pressure. Therefore, the pressure reduction expansion pressure compensation valve (102) controls any one of the first to fourth flow direction control valves (IO3) (104M105) (1) having the maximum load pressure.
06) is pressure compensated, that is, the differential pressure before and after the flow rate adjustment section is kept at a constant value corresponding to the spring force of the spring (119) in the spring chamber, and the flow rate is proportional to the opening degree of the flow rate adjustment section. 'is being treated as a Further, when the above =X to the fourth flow direction control valve (103) (1104) (105!06) are all in the neutral position,
2) spring chamber and each shuttle valve (115) (116) (
Ports at both ends of each flow direction control valve (103)
) (104) (105) (106) and a vent line (121) passing through the load pressure detection port (Cdl) and the tank passage (113).

Each flow direction control valve fln3) (104M105) (10
Each pilot passage (108) provided in 6) is connected to the decompression expansion pressure compensating valve (102) D via a line (122).
Connected to the secondary side. This line (122) connects each flow direction control valve (103) (104M105) (106
) communicate with the tank (114) via each pilot passage (108) and vent line (121) when all are in the neutral position, and are closed when any of them is in the switching position. There is.

The spring chamber of the decompression expansion pressure compensation valve (102) is communicated with the tank (114) via a relief valve (123), and for example, when the actuator reaches the stroke end, the pressure in the spring chamber decreases. When the pressure exceeds a predetermined pressure, the fluid in the spring chamber is released to the tank (114), and each flow rate directional control valve (103) (104) (105) (10
6) and to prevent damage to each actuator.

Furthermore, the secondary side of the decompression expansion pressure compensation valve (102) is connected to the pump unit +169) via the line (124).
and is connected to the pressure chamber of the load sensing valve (163) in the pump boat I- (160).

The pump unit (160) includes a variable displacement hydraulic pump (162) driven by an engine (161) and a load sensing valve (163). The spring chamber of this load sensing valve (163) is filled with the load pressure on the secondary side of the decompression expansion pressure compensation valve (102) or the above line (1
24) and the load sensing valve (1
The pressure of the main line (112) is transmitted to the pilot chamber 63), and the load sensing valve (163) is operated by fluctuations in both pressures.

Further, the port (yl of the load sensing valve (163) is connected to the main line (112), and the port (xl) of the load sensing valve (163) is connected to the tank (164). ) is communicated with a discharge amount control section (165) consisting of a swash plate control cape cylinder of a variable displacement hydraulic pump (162).

Next, the operating state of the hydraulic device (10) as described above will be explained.

First, the flow direction control valve (103) (104) (105M1
06) one of the flow rate directional control valves (103)
is in the switching position, in the device (100), the load pressure (Pi) of the flow direction control valve (103) is sent to the spring chamber of the vacuum expansion pressure compensation valve (102), and as a result, the pressure The pressure compensation valve (102) adjusts the pressure on its secondary side to a fluid pressure corresponding to the spring force (1) rather than the shear load pressure (1).
Try to maintain the pressure (P + P1) higher by Pl).

On the other hand, the pressure on the secondary side of this decompression expansion pressure compensation valve (102) is led to the spring chamber of the loader sensing valve (163) via the line (124), so the variable capacity The type hydraulic pump (162) is connected to the main line (11
2) When the pressure of the load sensing valve (
The set pressure (PiP, l) is higher by the fluid pressure (P2) corresponding to the spring force of the load sensing valve (1, 63) than the pressure (PiP, l) introduced into the negative chamber at / of 163).
2) The fluid is discharged as follows. That is, the main line (112) 17) fluid pressure is equal to the fluid pressure (P2) corresponding to the spring force of the load sensing valve (163) and the load pressure (P+P) transmitted to this spring chamber.
x), the loader sensing valve (163) is located at the symbol position (V2) and the discharge amount control unit (165) is set to the tank (t64).
162) 17)
An attempt is made to increase the discharge amount and increase the fluid pressure in the main line (112). On the other hand, main line (112)
The fluid pressure is the spring force 1 of the load sensing valve (163)
If the load sensing valve (163) is higher than the sum (P+P10P2) of the fluid pressure (P2) and the load pressure (P0P1) transmitted to this spring chamber, the load sensing valve (163) moves to the symbol position (Vl). Located on the main line (112)
The fluid of the CI-K SE: / CI7 valve (163) 7
)(yizl to the discharge control unit (165) to reduce the discharge amount of the variable displacement pump (162) and lower the pressure in the main line (112). The fluid pressure in 112) is maintained at a pressure corresponding to the load pressure of the flow direction control valve (103) located at the switching position, and fluid with a flow rate higher than that required by the flow direction control well (103) is also discharged. In addition, the load pressure IPI of the flow direction control valve (103) in the switching position is stored in the spring chamber of the decompression expansion pressure compensation valve (102) as described above.
is transmitted, so the differential pressure before and after the flow rate adjustment part of the flow rate directional control valve (103) is - pressure reduction expansion pressure compensation valve (102)
Therefore, the flow rate directional control valve (103) is pressure compensated to flow the original fluid proportional to the opening degree of the flow adjustment section. Become.

When two or more flow direction control valves (103), (104), (105), and (106) in the hydraulic device (100) are in the switching position at the same time, the flow direction control valves (103)
) (104) (105) (106) is selected by the shuttle valves (115) (116) (117) and guided to the spring chamber of the decompression expansion pressure compensation valve (102). As a result, in this case as well, the pressure on the secondary side of the decompression and expansion pressure compensation valve (102) is lower than the maximum load pressure IPI by the fluid pressure (Pl) corresponding to the spring force.
), and this pressure on the secondary side (P-1-PL) is led to the spring chamber of the load sensing valve (163), so the variable capacity liquid The pressure pump (162) is connected to the main line (112)
The pressure is maintained at a pressure (P + Pl + P2) higher than the pressure (P + Pl) led into the spring chamber of the load sensing valve (163) by the fluid pressure (P2) corresponding to the spring force, and the flow direction is controlled. Valve (103)(104((105)(
106) does not discharge more fluid than the required flow rate.

However, in this case, the flow rate directional control valve with the highest load pressure (1
03) (104) (105) (106) will be pressure compensated by the decompression expansion pressure compensation valve (102) in the same way as above, but the flow rate directional control valve with a lower load pressure <103) (104) )(105)(106) cannot be performed. Therefore, these flow rate directional control valves (103) (104) (105) with low load pressure
) (106), by adjusting the throttle of the flow adjustment section, the pressure before the throttle is raised to the set pressure, and the pressure and flow rate of the fluid are adjusted.

On the other hand, flow rate directional control valves (103) (104) (105)
(106) all reach the neutral position, the secondary side of the pressure reducing type pressure compensation valve (102) is the line (122),
Each flow rate directional control valve (103M104) (105) (10
It will communicate with the tank (114) via the pilot passage (108) and vent line (121) provided in 6). In this case, the flow direction control valve (103) (104) (1
Each load pressure of 05) and (106) becomes zero. Therefore, the pressure on the secondary side of the decompression expansion pressure compensation valve (102) is maintained at the fluid pressure (Pl) corresponding to the spring force, and this pressure (PI) causes the fluid to flow through the line (122) and each flow direction control. Valve (103) (104) (105) (106)
pilot passage (108) and vent line (121)
) to the tank (114). In addition, the pressure (Pl) on the secondary side of the pressure reducing compensation valve (102) is transmitted to the load sensing valve (163) via the line (124), so the variable reciprocal hydraulic pump (162) The pressure of the main line (112) is maintained at a pressure (P10P2) higher than this pressure (PL) by the fluid pressure (P2) corresponding to the spring force of the load sensing valve (163).

As described above, in this hydraulic device (100).

The variable displacement hydraulic pump (162) always outputs a pressure (P+P 1+P) corresponding to the load pressure IPI of the actuator.
2) and undyed fluid are discharged, making it possible to save power, and the flow rate directional control valve (103) (104) (105) (1
06) pressure compensation can also be performed. Furthermore, flow rate directional control valves (103) (104) (105) (106)
Even when all of the flow direction control valves (103), (104), (105, and )(IO2)(105)(1
06) is not cooled, and therefore thermal shock can be prevented. In this case, the flow rate of the fluid flowing in the pilot passage (108) is determined by the spring force of the pressure reduction expansion pressure compensation valve (102), the number of flow direction control valves (103) (104) (105) (106), and the pilot passage. (108), so these are appropriately selected within a range that can minimize power loss and prevent thermal shock.

In addition, in the above-described device (100), a relief valve (123) is provided to communicate the spring chamber of the decompression and expansion pressure compensation valve (102) with the tank passage (113) when the pressure reaches a predetermined pressure or higher. Instead, for example, as shown in Figure @2, a throttle <125) is interposed in the line (124) leading the secondary side of the No.2 pressure reducing type pressure compensating valve (102) 17) to the load sensing valve (163). , a line (126) communicating with the tank passage (113) is branched from the line (124), and a relief valve (12) is connected to this branched line (126).
7) may be provided.

Next, a second embodiment of the present invention shown in FIG. 3 will be described. This hydraulic device (200) and the base device (100) shown in FIG.
) is different in the following configuration, and this difference will be explained below. That is, while the hydraulic system shown in FIG. 1 uses a decompression expansion pressure compensation valve (102), this hydraulic system (200) uses a preferential expansion pressure compensation valve 1240). This gutter tip type pressure compensation valve (240) is a type of pressure reduction and expansion pressure compensation valve, but it has a primary port (241),
Normally open decompression port (242) and normally closed bypass port)
(243) is a known 3-port pressure compensating valve having a primary bow) (241) and a pressure reducing port (242) by controlling the opening degree between the pressure reducing port (242) and the priority line ( 244) while immersively compensating the pressure.

Excess fluid is discharged to a bypass port (243) and a bypass line (245).

The primary baud of the preferential expansion pressure compensation valve (240) (24
1) Pump boat 1 via main line (212)
(260), but its decompression port) (24
2) is connected to the first to third flow rate directional control valves (203) (204) (205) via the priority line (244).
The pump ports of are connected in parallel, and the primary port (21) of the decompression expansion pressure compensation valve (202) is connected to the bypass port (243) via the bypass line (245).
1) is connected.

The secondary port +209 of this pressure reducing type pressure compensator 1 prize valve (202) is connected to the pump boat of the fourth flow direction control valve (206).

The above-mentioned Iig work or third flow directional control valve (203,) (
The maximum pressure detected at each load detection port 1-fdi of 204) and 205 is selected by the shuttle valves (215 and 216), and the maximum pressure is selected by the throttle valve (218).
is led to the spring chamber of the preferential expansion pressure compensation valve (240). Therefore, the preferential expansion pressure compensation valve (241
1), the first to third flow direction control valves (203) (204) (205) having the maximum load pressure are preferentially compensated for the pressure, that is, the differential pressure before and after the flow rate adjustment section is compensated for by the preferential expansion pressure compensation valve. (240) is maintained at a constant value corresponding to the spring force, so that a flow rate proportional to the opening degree of the original adjustment section can flow. Furthermore, when the first to third flow direction control valves (203), (204), and (205) are all in the neutral position, the spring chamber of the preferential expansion pressure compensation valve (240) and each shuttle valve ( Both end ports of 215) + 216) are connected to each flow direction control valve (203) (204) (205).
) and vent line (220) and vent line (2
21) to communicate with the tank passage (213).

The pilot passage (208) provided in the direction control valve (203) (204M205) is connected to the secondary side of the preferential expansion pressure compensation valve (240) via a line (222), and this line ( 222) is the first to third
When the flow direction control valves (203), (204), and (205) are all in the neutral position, each pilot passage (208
) and the tank passage (
213) and are closed when either of them is in the switching position.

Load pressure detection port H of the fourth flow direction control valve (206)
The detected pressure in d) is led to the spring chamber of the vacuum expansion pressure compensation valve (202) through the throttle (2 turns), and therefore the fourth flow direction control valve (206) is connected to the vacuum expansion pressure compensation valve (202). The pressure is compensated by the valve (202), and the differential pressure before and after the flow rate adjustment section is maintained at a constant value corresponding to the spring force of the pressure reduction and expansion pressure compensation valve (202). When the fourth flow direction fi11a valve (206) is in the neutral position, the spring chamber of the decompression and expansion pressure compensation valve (202) is connected to the vent passage (220) provided in the flow direction control valve (2 (16)). )
and the tank passageway (21) via the vent line (247).
3). Furthermore, the pilot passage (20
8) is connected to the secondary side of the decompression expansion pressure compensation valve (202) via a line (248), and o1 Konolife (
248) communicates with the tank passage (213) via the pilot passage (208) and vent line (247) when the fourth flow directional control well C206) is in the neutral position, and also communicates with the pressure reduction and expansion pressure force compensation valve. (206) is adapted to be closed when it is in the switching position.

In addition, the priority line (2) of the priority turgor force compensation valve (240)
44) and the pressure on the secondary side of the upper pressure reducing type pressure compensation valve (202), the maximum pressure is selected by the shuttle valve (217), and the pressure is transferred to the pump unit (260) via the line (224). and the pump unit (260
) into the spring chamber of the load sensing valve (263).

As mentioned above, in this hydraulic system ft (200),
Since the variable displacement hydraulic pump [262] always discharges fluid at a pressure and flow rate corresponding to the load pressure of the actuator, it is possible to save the movement force by θ%, and it is also possible to save the force by θ%. The first to third flow direction control valves (203X204) where the load pressure is maximized by the compensation valve (240)
) (205) (7) Pressure compensation and pressure compensation of the fourth flow direction control valve (206) can also be performed at the same time by the pressure reduction and expansion pressure compensation valve (202). Furthermore, even when the flow rate directional control valves (203), (204), (205), and (206) are all in the neutral position, each flow direction 'rFi
Since there is fluid flowing in the pilot passage (208) provided in the IJ control valve (203) < 204) (205M206), the flow rate directional control valve (203) (204) (205
) (206) is not cooled, and therefore thermal shock can also be prevented from occurring.

In addition, since a priority expansion pressure compensation valve (240) is used, the first to third flow direction control valves (203) perform the main operation.
(204) and (205), the fourth flow direction control valve (206)
) can be controlled preferentially.

Although the present invention has been described in detail above, the hydraulic device for sale is not limited to the above-mentioned embodiments, and various types including the type and number of the decompression expansion pressure compensation valve and the type and number of flow rate directional control valves can be used. It is obvious that the invention can be implemented with modifications in this respect.

The hydraulic device of the present invention is configured as described above, and therefore, even when the flow direction control valve is in the neutral position, the fluid flowing inside the flow direction control valve can be controlled. As a result, it is possible to prevent the occurrence of thermal shock. Moreover, since the hydraulic pump always discharges fluid at a pressure and flow rate that match the load pressure of the actuator, power can be saved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the hydraulic device of the present invention;
FIG. 2 is a circuit diagram showing a partial modification of the above embodiment, and FIG. 3 is a circuit diagram showing a second embodiment of the present invention. (100M200)... Hydraulic device, (102) (20
2)...Decompression expansion pressure compensation valve, (240)...Priority expansion pressure compensation valve, (103) (203)...First flow meter directional control valve, (104M204)...Second flow direction control valve Directional control valve, (105) (205)...Third flow rate directional control valve. (106) (206)...@4 flow rate directional control valve, (1
08) (208)... Pilot passage, (113) (
213)... Tank passage, (162) (262)...
・Variable capacity forming pressure pump, (163)(263)・
...Load sensing valve, (165)...Discharge d
Control unit, ldl...Load pressure detection port

Claims (1)

[Claims] 1. A vacuum expansion pressure compensation valve (102) is installed in the discharge path of a variable displacement hydraulic pump (162) equipped with a discharge amount control unit (165).
and connect the primary side of the pressure reducing expansion pressure compensation valve α02).
A flow direction control valve (103) is connected to the secondary side of the flow direction control valve (103), and the pressure at the front side of the flow direction control valve (103) is connected to the pilot chamber of the pressure reduction/expansion pressure compensation valve (102), and the pressure at the rear side is connected to the spring. the flow rate directional control valve (103).
has a pilot passage (113) which communicates with the tank passage (113) in its neutral position and is closed in its switching position.
108), the pilot passageway (108) is connected to the secondary side of the decompression expansion pressure compensation valve (102), and the primary side of the decompression expansion pressure compensation valve (102) is connected to a load sensing valve (163). In the pilot room, Mikai,
゛ The primary and secondary sides are connected to the spring chamber, respectively, and the load sensing valve (163) controls the discharge amount control section (165).
A hydraulic device that controls the discharge amount by switching and communicating the control chamber between the discharge passage and the tank passage.