JPS59190503A - Liquid pressure device - Google Patents

Abstract

PURPOSE:To make a liquid pressure device in a simple construction by allowing the pressure in a pump discharge line plus either of the pressure in a priority line of a priority type pressure compensative valve and the pressure behind a rate and direction control valve in a by-pass line to operate a load sensing valve, and thereby performing control of the pump. CONSTITUTION:When a rate and direction control valve 11 in a priority line 6 and a rate and direction control valve 14 in a by-pass line 7 are switched, a shuttle valve 27 selects either the pressure P behind the valve 14 or the pressure, which is higher than the pressure P1 behind the valve 11 by an amount corresponding to a spring force P2 of a priority type pressure compensative valve 2, and if the pressure P, for ex., is selected, it is applied to a spring chamber in a load sensing valve 63 to mate with the fluid pressure in a discharge line 8, so that a variable capacity pump 62 is controlled so that the pressure in the duscharge line 8 is held at the sum of the pressure P and the spring force P3 of said valve 63. Thus the valves 11, 14 are both pressure compensated. This liquid pressure device A does not require any alteration of the piping when flow control valves 11-13 in the priority line 6 are increased or decreased.

Description

[Detailed Description of the Invention] This invention relates to a hydraulic device, and in particular, it is possible to save power and increase the number of flow direction control valves according to the number of actuators, and in this case, no special external piping is required. This is related to the number of hydraulic equipment that is not required.

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. 51-51682. This device has a pressure reducing type pressure compensation valve interposed in the mainstream circuit upstream of the variable orifice of the flow direction control valve, and connects the viroft line branched from the rear of the variable orifice to the splash chamber of the pressure reducing expansion pressure compensation valve. Further, the virofloft line is 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.

By the way, conventionally, a device for controlling a flow rate directional control valve that controls the fluid guided to an actuator that performs the main operation preferentially over other flow rate directional control valves is disclosed in, for example, JP-A-57-107407. As described, connect the primary side of the priority expansion pressure compensation valve to the discharge path of the hydraulic pump, and control the actuator that performs the main operation via the priority line to the pressure reduction port of this priority expansion pressure compensation valve. In addition to connecting the flow rate directional control valve, other flow rate directional control valves were connected to the bypass port via the bypass line, and while the priority line was pressure compensated preferentially, excess fluid was discharged to the bypass line. In this hydraulic system, the pressure at the front side of the flow direction control valve on the priority line side is introduced into the pilot chamber of the priority expansion pressure compensation valve, and the pressure at the rear side is introduced into the splash chamber. The maximum pressure between the pressure downstream of the flow rate directional control valve and the pressure downstream of the flow rate directional control valve on the bypass line side is selected by the Shale valve, and the selected maximum pressure is applied to the load sensing valve's splash chamber. In addition, it is possible to save power by guiding the pressure of the discharge passage to its pilot chamber.

However, in such a device, a pair of piping is required in order to compare the pressure on the priority line side and the pressure on the bypass side using a shuttle valve, and this shuttle valve cannot be built into the valve. Therefore, the pair of pipes cannot be connected externally, resulting in a problem that the structure becomes complicated.

This invention was made in view of the above, and its purpose is to save power, and also to use the priority line side piping connected to the shuttle valve as the priority line passage.
An object of the present invention is to provide a hydraulic device whose structure can be simplified.

The hydraulic device of the present invention, which achieves the above object, connects the primary side of the preferential expansion pressure compensation valve to the discharge path of a variable displacement hydraulic pump equipped with a discharge amount control section controlled by a load sensing valve. In a hydraulic system in which a flow rate directional control valve is connected to the pressure reducing port of the turgor pressure compensation valve via a priority line, and another flow rate directional control valve is connected to the bypass port via a bypass line, the above priority The front pressure of the flow direction control valve on the priority line side is introduced into the pilot chamber of the expansion pressure compensation valve, and the rear pressure is introduced into the spring chamber, and the pressure of the priority line and the flow rate on the bypass line side are introduced. The shuttle valve selects the maximum pressure with respect to the pressure downstream of the directional control valve, and guides the selected maximum pressure to the splash chamber of the load sensing valve and the pressure of the discharge path to its pilot chamber, and The present invention is characterized in that the control chamber of the discharge amount control section is switched to communicate with the discharge path and the tank path by a valve to control the discharge amount.

As described above, the shuttle valve selects the maximum pressure between the priority line pressure and the downstream pressure of the flow direction control valve on the bypass line side, and directs the selected maximum pressure to the spring chamber of the load sensing valve. Therefore, even if you want to add a new flow direction control valve to the priority line side, if you provide the flow direction control valve with a priority line that passes through the valve block and communicates with the pump port, this line pressure will be led to the shuttle valve via the existing line. Therefore, there is no need to provide new piping or the like.

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

As shown in the figure, this hydraulic device (A) includes a valve unit (1) for controlling fluid supplied to an actuator, and a pump unit (6o) for supplying fluid to this valve unit (1). has.

The valve unit (1) has a priority expansion pressure force compensation valve (2), and this priority expansion pressure force compensation valve (2)
- (3), a normally open pressure reducing port (4) and a normally closed bypass port (5), the primary port (3) and the pressure reducing port (4) The priority line (6) on the depressurization port (4) side is preferentially compensated for by controlling the opening degree between them, while excess fluid is transferred to the bypass port (
5) to the bypass line (7).

The primary port (3) of the priority expansion pressure compensation valve (2) is connected to the discharge path (8) of the bomb Unisol l-(60), but the priority line (6) is connected to its pressure reduction port (4). via the first to third flow rate directional control valves (11) (12)
Each pump port (13) is connected in parallel, and the bypass port (5) is connected to a bypass line (7).
The pump boat of the fourth flow rate directional control valve (14) is connected via. In addition, these first or first flow rate directional control valves (11) (12) (13) (14)
Each tank port is connected to a tank (16) via a tank passage (15).

The first to fourth flow rate directional control valves (11) (1
2), (13), and (14) all have the same structure, so only the first flow rate directional control valve (11) will be explained here, but this flow rate directional control valve (11) is a directional control valve. It has a load detection port (d) that can detect the pressure downstream of the flow rate adjustment section (not shown) via the feed puncture passage (17) at the switching position. This load detection port (d
) is connected to the vent line (1) via the vent passage (18) when the flow direction control valve (11) is in the neutral position.
9) to the tank passage (15).

Furthermore, the flow rate directional control valve (11) is provided with a pilot passage (20) which communicates with the tank passage (15) when in its neutral position and which is closed when in its switching position.

The first to third flow rate directional control valves (11) (1
2) The maximum pressure detected in (13) is selected by the shuttle valve (21) C22), and the priority expansion pressure compensation valve (2) is selected via the throttle (23). is being led to the spring chamber. Further, the pressure in the priority line (6) of the priority inflation pressure compensation valve (2) is guided to the pilot chamber of this priority inflation pressure compensation valve (2), and opposes the pressure introduced to the spring chamber.

Therefore, the pressure at the pressure reduction port (4) of the priority expansion pressure compensation valve (2) is adjusted to the shuttle valve (21) (22) as described above.
The pressure is maintained higher than the maximum load pressure selected by the fluid pressure corresponding to the spring force of the preferential expansion pressure compensation valve (2). Therefore, the preferential expansion pressure compensating valve (2) controls the first to third valves having the maximum load pressure.
The flow rate directional control valves (11, 12, and 13) are preferentially compensated for the pressure, that is, maintained at a constant value corresponding to the spring force of the spring chambers before and after the flow rate adjustment section, and proportional to the opening degree of the flow rate adjustment section. It is designed to be able to flow at a certain flow rate. In addition, the first to third flow rate directional control valves (11) (12)
(13) are all in the neutral position, the spring chamber of the preferential expansion pressure compensation valve (2) and each shuttle valve (21
) The ports at both ends of (22) are connected to each flow rate directional control valve (
11), (12> (13))
8) and a vent line (19) passing through the load detection port (d) to communicate with the tank passage (15).

The pilot passage (20) provided in each flow direction control valve (11) (12) (13) is connected to the priority line (6) of the priority expansion pressure compensation valve (2) via a line (24).
It is connected to the. This line (24) is connected to the tank (16) via each pilot passage (20) and vent line and are closed when either of them is in the switching position.

The splash chamber of the preferential expansion pressure compensation valve (2) is communicated with the tank (16) via a relief valve (25), and for example, when the actuator reaches the stroke end, the pressure in the splash chamber decreases. When the pressure exceeds a predetermined pressure, the fluid in the splash chamber is released to the tank (16) to prevent damage to each flow rate directional control valve (11) (12) (13) and each actuator. There is.

The detected pressure at the load detection boat (d) of the fourth flow direction control valve (14) is transmitted to the shuttle valve (2) via the throttle (26).
7) and is compared with the pressure of the priority line (6), which is guided by this shuttle valve (27) via line (28), and its maximum pressure is selected. The selected maximum pressure is then led to a pump unit (60), which will be described later, via a line (29). Note that when the fourth flow rate directional control valve (14) is in the neutral position, the load detection port (d) communicates with the tank (16) via the Ghent passage (18) and the line (30). It is done like this. In addition, the load detection port (d) communicates with the tank (6) via the relief valve (31) in order to prevent damage to the fourth flow rate directional control valve (14) and the actuator, as described above.

The pump unit (60) includes a variable displacement wave pressure pump (62) driven by an engine (61) and a load sensing valve (63).

The maximum pressure selected by the shuttle valve (27) is led to the pressure chamber of this load sensing valve (63) via the line (29), and the load sensing valve (63)
The pressure of the discharge passage (8) is transmitted to the biloft chamber 63), and the load sensing valve (63) can be operated by fluctuations in both positive forces. Further, the boat (y) of the load sensing valve (63) is communicated with the discharge passage (8), and the boat (X) of the load sensing valve (63) is connected to the discharge passage (8).
is connected to the tank (64). Bow 1- (Z) of the load sensing valve (63) is communicated with a discharge amount control section (65) consisting of a swash plate control cylinder of a variable displacement wave pressure pump (62).

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

First, the first to third flow direction control valves (11) (1
2)' (13), for example, the case where the first flow rate directional control valve (11) is in the switching position will be explained. In this case, the load pressure (Pl) downstream of the flow direction control valve (11) is sent to the spring chamber of the preferential expansion pressure compensation valve (2), and as a result, the preferential expansion pressure compensation valve (2) The pressure of the priority line (6) is set to be higher than the load pressure (Pl) by the fluid pressure (P2) corresponding to the spring force.
L 10P2). On the other hand, the pressure (Pl + P2) of this priority line (6) is led to the spring chamber of the load sensing valve (63) via the shuttle valve (27) and line (29), so the variable displacement wave pressure pump (6
2) The pressure in the discharge passage (8) is the pressure (P1+) led to the spring chamber of the load sensing valve (63) as described above.
The set pressure (Pi +
P2 + P3). That is, the fluid pressure in the discharge passage (8) is the fluid pressure (P3) corresponding to the spring force of the load sensing valve (63).
If the load pressure (PL + P2) transmitted to the splash chamber is lower than the sum (PI + P2 + P3), the load sensing valve (63) moves to the symbol position (v2).
, the discharge amount control unit (65) is communicated with the tank (64), the discharge amount of the variable displacement wave pressure pump (62) is increased, and the fluid pressure in the discharge path (8) is increased. shall be. On the other hand, the fluid pressure in the discharge passage (8) is a fluid pressure (P3) corresponding to the spring force of the load sensing valve (63);
When the load pressure (Pl, +P2) transmitted to this spring chamber is higher than the sum (P'l + P2 + p3), the load sensing valve (63) moves to the symbol position (vl
), the fluid in the discharge path (8) is guided to the discharge amount control unit (65) through the boats (y) and (z) of the load sensing valve (63) to control the variable displacement wave pressure pump (62). An attempt is made to reduce the discharge amount and lower the pressure in the discharge passage (8). In this way, the fluid pressure in the discharge passage (8) is maintained at a fluid pressure corresponding to the load pressure of the flow directional control valve (11) in the switching position, and the flow directional control valve (11)
Fluid that exceeds the flow rate required by the pump will not be discharged. In addition, since the load pressure of the flow rate directional control valve (11) in the switching position is transmitted to the splash chamber of the priority expansion pressure compensation valve (2), the flow rate directional control valve (11) is in the switching position as described above. The differential pressure before and after the flow rate adjustment section is maintained at a fluid pressure (P2) corresponding to the spring force of the priority liver pressure compensation valve (2), and therefore the flow rate directional control valve (11) is pressure compensated. The flow rate is proportional to the opening of the flow rate adjustment section.

When two or more of the first to third flow direction control valves (1, 1) (12) (13) in the hydraulic device (A) are in the switching position, these Flow rate directional control valve (11) (12) (1
3), the maximum load pressure (Pl) is the shuttle valve (21)
(22) is selected by the priority inflation pressure compensation valve (2
) is led to the spring chamber. As a result, in this case as well, the fluid pressure in the priority line (6) of the priority expansion pressure compensation valve (2) is lower than the maximum load pressure (Pl) by the fluid pressure (P2) corresponding to the spring force. fluid pressure (PL +
P2), and the fluid pressure in the discharge passage (8) is also maintained at (PL + P2 + P3) in the same way as above. However, in this case, the flow rate directional control valve with the highest load pressure will be pressure compensated in the same way as above, but the pressure compensation of the flow rate directional control valve with a lower load pressure will no longer be possible.

Therefore, for a flow rate directional control valve with a low load pressure, the pressure before the throttle is raised to a set pressure by adjusting the throttle of the flow rate adjusting section to adjust the fluid pressure and flow rate.

Next, the first to third flow direction control valves (11) (12) (13) connected to the priority line (6) are connected to the priority line (6).
), for example, the first flow direction control valve (1
1) and the fourth flow rate directional control valve (14) connected to the bypass line (7) are at the switching position at the same time. In this case, the fluid pressure in the priority line (6) is higher than the fluid pressure (PL) downstream of the first flow direction control valve (11) by the spring force (PL) of the priority expansion pressure compensation valve (2), as described above. P2) is maintained at a higher pressure (pl + P2) and this pressure is sent via line (28) to the shuttle valve (27).

On the other hand, the pressure (P) downstream of the fourth flow direction control valve (14)
The pressure is also sent via the throttle (26) to the shuttle valve (27), where the maximum pressure of the two positive forces, for example (P), is selected. This selected maximum pressure (P) is then sent via the line (29) to the spring chamber of the load sensing valve (63), and as a result the fluid pressure in the discharge passage (8) is changed to the fourth The load sensing valve (
The fluid pressure (P+P3) is higher by the spring force (P3) of
) will be maintained. As a result of the above, the priority line (
6) is the load pressure (Pl) of the first flow rate directional control valve (11)
The fluid pressure (pl + P2) is kept higher by the spring force (P2) of the preferential expansion pressure compensation valve (2) than the fluid pressure of the bypass line (7) through which the excess flow flows.
) will be maintained at a fluid pressure (p+P3). Therefore, both the first flow rate directional control valve (11) and the fourth flow rate directional control valve (14) are pressure-compensated, and flow a flow rate proportional to the opening degree of the flow rate adjustment section.

On the other hand, when all of the first to third flow rate directional control valves (11) (12) (13) of the priority line (6) are in the neutral position, the priority line (6) is
4) , each flow rate directional control valve (11) (1'2)
It will communicate with the tank (16) via a pilot passage (20) provided in (13) and a hentline (19). At this time, the load pressure introduced into the spring chamber of the preferential expansion pressure compensation valve (2) is zero. Therefore, the fluid pressure in the priority line (6) is maintained at a fluid pressure (P2) corresponding to the spring force of the priority expansion pressure compensation valve (2), and this fluid pressure (P2) causes the fluid to flow into the lines (24), It will flow to the tank (16) via the pilot passage (20) and hent line (19) provided in each flow directional control valve (11) (12) (13). By providing the pilot passage (20) in each flow rate directional control valve (11) (12) (13) in this way, when all flow rate directional control valves (11) (12) (13) are in the neutral position, Even if there is a fluid flowing through it, it is possible to prevent the occurrence of thermal shock.

As described above, in this hydraulic device (A), fluid is discharged from the variable displacement wave pressure pump (62) to the lightning at a fluid pressure and flow rate corresponding to the load pressure of the actuator. The flow rate directional control valve (11) (12) makes it possible to increase the power and maximize the load pressure.
), (13) and (14) pressure compensation can also be performed.

Furthermore, in addition to the above, it is important to note that this hydraulic device (A
)', it is not necessary to make any changes to the piping when increasing or decreasing the flow rate directional control valves (11)' (12) (13) connected to the priority line (6). be. For example, when attempting to remove the second flow rate directional control valve (12), the valve pro to which this flow rate directional control valve (technique 2) belongs.

(42) and remove the first flow direction control valve (11).
) to which the valve block (41) belongs and the third flow rate directional control valve (
11) may be connected to the valve block (43) to which it belongs. In addition, when adding another new flow rate directional control valve, the valve block (43) to which the third flow rate directional control valve (13) belongs and the valve block (44) to which the shuttle valve (27) belongs In between, a new flow directional control valve (13) has a new priority line (6) exactly similar to the valve block (43) to which it belongs, passing through the valve block and communicating with the tank boat of the flow directional control valve. Just insert a valve block. In this case, the priority line (6) of the valve block (43) to which the third flow rate directional control valve (13) belongs passes through the priority line (6) of the new valve block, and the shuttle valve (
27) to the shuttle valve (27) via the line (28) of the valve block (44) to which it belongs. In addition, 5, the vent passage (18) and the pilot passage (
20) will communicate with the hent line (19) through the vent passage (18) and pilot passage (20) of the new valve block, respectively, and the bypass line (
7) also communicates with the fourth flow rate directional control valve (14) in exactly the same way as above. In this way, in the hydraulic device (A),
Even if another new flow rate directional control valve is added, it is possible to perform the same operation as described above without making any changes to the piping or the like.

Although one embodiment of the present invention has been described above, it is obvious that the hydraulic device of the present invention is not limited to the above-described embodiment and can be implemented with various modifications.

The hydraulic device of the present invention is configured as described above. Therefore, according to the hydraulic device of the present invention, it is possible to save power and to connect the piping on the priority line side connected to the shuttle valve to the priority line. Since it can also be used as a passage, one piping is not required, and the structure is simplified, and since the shuttle valve can be built into the valve, the number of flow rate directional control valves on the priority line side can be easily increased or decreased.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the hydraulic device of the present invention. (2)...priority inflation pressure compensation valve, (4)...decompression boat, (5)...no\ipassport, (6)...priority line, (7)...no\ipass line , (8)...
Discharge path, (11)...first flow rate directional control valve, (12)
...Second flow rate directional control valve, (13)...Third flow rate directional control valve, (14)...Fourth flow rate directional control valve, (27
)...Shuttle valve, (62)...Variable displacement hydraulic pump, (63)...Load sensing valve, (65)...
...discharge rate control section, (A) ...hydraulic pressure device.

Claims (1)

[Claims] 1. Variable displacement wave pressure pump (6) equipped with a discharge amount control section (65) controlled by a load sensing valve (63)
Connect the negative side of the preferential expansion pressure compensation valve (2) to the discharge path (8) of the preferential expansion pressure compensation valve (2), and
4) is connected to the flow direction control valve (1) via the priority line (6).
1) and another flow rate directional control valve (14) connected to the 7N/Ip port (5) via a bypass line (7), the preferential expansion pressure compensation valve ( 2) The above priority line (6) is placed in the pilot room.
The front pressure of the side flow rate directional control valve (11) and the rear pressure are guided to the splash chamber, respectively, and the pressure of the above priority line (6) and the flow rate of the above bypass line (7) side are introduced. The shuttle valve (27) selects the maximum pressure with respect to the pressure downstream of the directional control valve (14), and the selected maximum pressure is applied to the spring chamber of the load sensing valve (63) and the discharge path (8). The pressure is guided to the respective pilot chambers, and the load sensing valve (63) controls the discharge amount control section (63).
A hydraulic device characterized in that the control chamber (5) is switched and communicated with the discharge passage (8) and the tank passage to control the discharge amount.