EP4596898A1

EP4596898A1 - Fluid pressure equipment and fluid pressure system

Info

Publication number: EP4596898A1
Application number: EP23871393.7A
Authority: EP
Inventors: Takaaki Adachi
Original assignee: KYB Corp
Current assignee: KYB Corp
Priority date: 2022-09-30
Filing date: 2023-07-19
Publication date: 2025-08-06
Also published as: WO2024070149A1; JP2024052002A

Abstract

The valve device (100) includes the housing (10) provided with the load pressure passage (15) configured to guide the load pressure (Pls) to the variable displacement pump, the variable displacement pump being configured such that the discharge capacity is controlled in accordance with the self pressure (Pps) discharged by the variable displacement pump and the load pressure (Pls) supplied, wherein the housing (10) further includes: the pump passage (11) configured to guide the working oil sucked from the tank and discharged by the pump; the tank passage (12) configured to return the working oil discharged by the pump to the tank; and the communication passage (17) having both ends communicating with the tank passage (12), and wherein at least a potion of the communication passage (17) is arranged adjacent to the load pressure passage (15) such that the portion is separated from the load pressure passage (15) only by the wall portion of the housing (10) without any other passage guiding the working oil interposed between the portion and the load pressure passage (15).

Description

TECHNICAL FIELD

The present invention relates to a fluid pressure apparatus and a fluid pressure system.

BACKGROUND ART

JP1993-187411A discloses a hydraulic driving device for a hydraulic working machinery including: flow rate control means that controls a discharge flow rate of a variable displacement hydraulic pump; differential pressure detection means that detects a differential pressure between a discharge pressure of the variable displacement hydraulic pump and a load pressure of an actuator; target differential pressure setting means that sets a target value for the differential pressure between the discharge pressure of the hydraulic pump and the load pressure of the actuator as a target differential pressure; and control means that outputs, in accordance with a signal output from the differential pressure detection means, a driving signal to the flow rate control means such that the differential pressure between the discharge pressure of the variable displacement hydraulic pump and the load pressure of the actuator matches the above-described target differential pressure.

SUMMARY OF INVENTION

In the fluid pressure apparatus described in JP1993-187411A , the load pressure of the actuator is guided to the differential pressure detection means as a signal pressure, and a discharge capacity of the pump is controlled on the basis of the signal pressure and a discharge pressure of a pump serving as a self pressure. Normally, because it suffices that the pressure is transmitted as the signal, in the signal pressure passage that guides the signal pressure, the flow rate of a working fluid in the signal pressure passage is limited so as to be lower than that in a pump passage that guides the self pressure.
Meanwhile, in the fluid pressure apparatus, in order to ensure operational responsiveness, the working fluid may be warmed by a warm-up operation in which the pump is driven. However, because the signal pressure passage is not configured so as to actively cause the flow of the working fluid therein as described above, it is difficult to sufficiently warm the working fluid in the signal pressure passage even if the warm-up operation is performed. Therefore, a difference is caused in the responsiveness between the self pressure and the signal pressure, and as a result, there is a risk in that the responsiveness of a capacity control of the pump is lowered.
An object of the present invention is to provide a fluid pressure apparatus capable of improving a responsiveness of a capacity control of a pump.
According to one aspect of the present invention, a fluid pressure apparatus includes a housing provided with a signal pressure passage configured to guide a signal pressure to a variable displacement pump, the variable displacement pump being configured such that a discharge capacity is controlled in accordance with a self pressure discharged by the variable displacement pump and the signal pressure supplied. The housing is further provided with: a pump passage configured to guide a working fluid sucked from a tank and discharged by the pump; a tank passage configured to return the working fluid discharged by the pump to the tank; and a communication passage having both ends communicating with the tank passage. At least a potion of the communication passage is arranged adjacent to the signal pressure passage such that the potion is separated from the signal pressure passage only by a wall portion of the housing without any other passage guiding working fluid interposed between the potion and the signal pressure passage.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a hydraulic circuit diagram of a fluid pressure system according to an embodiment of the present invention.
[FIG. 2] FIG. 2 is a schematic view showing a configuration of a valve device according to the embodiment of the present invention.
[FIG. 3] FIG. 3 is a sectional view taken along a line III-III in FIG. 2.
[FIG. 4] FIG. 4 is a sectional view taken along a line IV-IV in FIG. 2, and is a diagram showing a mating surface of one valve block to other valve block.

DESCRIPTION OF EMBODIMENTS

A fluid pressure apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following, a case in which the fluid pressure apparatus is a valve device 100 that controls communication of a pump P and a tank T with a hydraulic cylinder 1 serving as a fluid pressure actuator will be described as an example.
The valve device 100 switches the supply and discharge of a working oil (a working fluid) to and from the hydraulic cylinder 1, and controls the operation of the hydraulic cylinder 1. In this embodiment, although an example in which the working oil is used as the working fluid will be described, other fluids such as hydraulic water, etc. may also be used as the working fluid.
The valve device 100 and a fluid pressure system 1000 including the same will be described first with reference to FIG. 1.
The fluid pressure system 1000 includes: the hydraulic cylinder 1 that is operated by supply and discharge of the working oil serving as the working fluid; the tank T that stores the working oil; the variable displacement pump P that sucks the working oil from the tank T, and pressurizes and discharges the working oil; a control mechanism 110 that controls a discharge capacity of the pump P; and the valve device 100 that controls the flow of the working oil supplied to and discharged from the hydraulic cylinder 1.
As shown in FIG. 1, the hydraulic cylinder 1 is a double acting type cylinder having a piston 4 that partitions an interior of a cylinder tube 2 into a rod-side chamber 5 serving as a first fluid pressure chamber and a bottom-side chamber 6 serving as a second fluid pressure chamber. A piston rod 3 is connected to the piston 4. A tip end of the piston rod 3 is linked to a load (not shown), which is a drive target.
The working oil is supplied to and discharged from the rod-side chamber 5 of the hydraulic cylinder 1 through a rod-side passage 13. The working oil is supplied to and discharged from the bottom-side chamber 6 of the hydraulic cylinder 1 through a bottom-side passage 14.
The hydraulic cylinder 1 is extended as the working oil is supplied to the bottom-side chamber 6 and the working oil is discharged from the rod-side chamber 5. Conversely, the hydraulic cylinder 1 is contracted as the working oil is supplied to the rod-side chamber 5 and the working oil is discharged from the bottom-side chamber 6.
The pump P is a variable displacement piston pump whose discharge capacity is changed according to the tilt angle of a swash plate (not shown). The pump P may be of other type, such as a variable displacement vane pump, etc., for example.
The discharge capacity of the pump P is controlled by the control mechanism 110 on the basis of a differential pressure between a self pressure Pps, which is the pressure of the working oil discharged by the pump P itself, and a load pressure Pls of the hydraulic cylinder 1 serving as a signal pressure. Specifically, the control mechanism 110 has: a regulator 111 to which the self pressure Pps and the load pressure Pls are respectively guided and which generates a control pressure Pc according to the differential pressure between the self pressure Pps and the load pressure Pls; and a control actuator 112 that controls the discharge capacity by driving the swash plate of the pump P in accordance with the control pressure Pc guided from the regulator 111. The control actuator 112 is a single-acting type hydraulic cylinder that is extended and contracted in accordance with the supplied control pressure Pc, for example. By driving the control actuator 112 in accordance with the control pressure Pc based on the differential pressure between the self pressure Pps and the load pressure Pls, the discharge capacity of the pump P is controlled such that the differential pressure between the self pressure Pps and the load pressure Pls remains constant.
The valve device 100 includes: a control valve 20 that controls the flow of the working oil supplied to and discharged from the hydraulic cylinder 1; a pump passage 11 through which the working oil discharged by the pump P is guided; a tank passage 12 that guides the working oil discharged by the pump P and returned to the tank T; the rod-side passage 13 that communicates with the rod-side chamber 5; the bottom-side passage 14 that communicates with the bottom-side chamber 6; a load pressure passage 15 serving as the signal pressure passage that guides the load pressure Pls serving as the signal pressure; a communication passage 17 that communicates with the tank passage 12 at its both ends; a relief valve 30 that is opened when the self pressure Pps (the discharge pressure) of the pump P reaches a predetermined relief pressure and allows the working oil discharged from the pump P to return to the tank T; and an unloading valve 40 that relieves the self pressure Pps (the discharge pressure) of the pump P to the tank T in accordance with the differential pressure between the self pressure Pps and the load pressure Pls.
The pump passage 11, the tank passage 12, the rod-side passage 13, the bottom-side passage 14, and the load pressure passage 15 are connected to the control valve 20.
The control valve 20 is a spool valve whose position is switched as a spool (not shown) is moved in accordance with the pilot pressure respectively supplied to pilot chambers 21a and 21b and the biasing force exerted by springs 22a and 22b each serving as a biasing member. The control valve 20 has a contracting position 20A at which the hydraulic cylinder 1 is contracted, an extending position 20B at which the hydraulic cylinder 1 is extended, and a neutral position 20C at which the working oil is not supplied to and discharged from the hydraulic cylinder 1.
When the pilot pressure is supplied to the first pilot chamber 21a, the control valve 20 is set to the contracting position 20A (the state shown in FIG. 1). At the contracting position 20A, the pump passage 11 communicates with the rod-side passage 13 and the load pressure passage 15 via a restrictor 23, and the bottom-side passage 14 communicates with the tank passage 12. As a result, the working oil is supplied to the rod-side chamber 5 and the working oil is discharged from the bottom-side chamber 6, and thus, the hydraulic cylinder 1 is contracted.
When the pilot pressure is supplied to the second pilot chamber 21b, the control valve 20 is set to the extending position 20B. At the extending position 20B, the pump passage 11 communicates with the bottom-side passage 14 and the load pressure passage 15 via the restrictor 23, and the rod-side passage 13 communicates with the tank passage 12. As a result, the working oil is supplied to the bottom-side chamber 6 and the working oil is discharged from the rod-side chamber 5, and thus, the hydraulic cylinder 1 is extended.
In a state in which the pilot pressure is not supplied to any of the pilot chambers 21a and 21b, the control valve 20 is set to the neutral position 20C by the biasing force exerted by the springs 22a and 22b. At the neutral position 20C, the respective communications of the pump passage 11 and the tank passage 12 with the rod-side passage 13 and the bottom-side passage 14 are shut off, and the pump passage 11 and the load pressure passage 15 are communicated with the tank passage 12.
The pressure is guided to the load pressure passage 15 at the same level as the working oil discharged by the pump P and supplied to the hydraulic cylinder 1 via the restrictor 23, which is provided on the control valve 20. The pressure of the working oil in the load pressure passage 15 is guided to the regulator 111 as the load pressure Pls. In addition, the pressure of the working oil in the pump passage 11, which has been discharged by the pump P and which is guided to the control valve 20, is guided to the regulator 111 as the self pressure Pps. In addition, the load pressure passage 15 communicates with the tank passage 12 via a restrictor 50.
Both ends of the communication passage 17 communicate with the tank passage 12, and the working oil in the tank passage 12 is guided to the communication passage 17. Any other passages are not connected to the communication passage 17. In addition, no hydraulic equipment, such as a valve, etc. is also provided on the communication passage 17. In other words, the working oil in the tank passage 12 is only guided to the communication passage 17, and the communication passage 17 does not affect the function of the valve device 100 that controls the flow of the working oil, and so, the communication passage 17 is a passage that merely bypasses the tank passage 12 by being branched from the tank passage 12 and joined with the tank passage 12.
The relief valve 30 is provided in a relief passage 18 through which the pump passage 11 and the tank passage 12 are communicated. The relief valve 30 is opened when the pressure in the pump passage 11 reaches a predetermined relief pressure, and thereby, the working oil discharged by the pump P is allowed to flow into the tank T.
The unloading valve 40 is provided in an unload passage 19 that communicates with the pump passage 11 and the tank passage 12. The unloading valve 40 is opened when the differential pressure between the self pressure Pps of the pump P and the load pressure Pls reaches a predetermined valve opening pressure, and thereby, the working oil discharged by the pump P is allowed to flow into the tank T.
Next, specific configurations of the valve device 100 and the communication passage 17 will be described with reference to FIGs. 2 to 4.
As shown in FIG. 2, the valve device 100 is formed of a plurality of valve blocks 101 (in this embodiment, five valve blocks) that are connected in a predetermined direction (the up-down direction in FIG. 2). Each of the valve blocks 101 has an independent housing 10, and the valve device 100 is integrally formed by connecting the housings 10 by means of bolts (not shown), etc.
In this embodiment, the communication passage 17 is provided in one valve block 101a, among the valve blocks 101, which is sandwiched between a pair of valve blocks 101b and 101c. In other words, the valve block 101a, in which the communication passage 17 is provided, is connected to other valve blocks 101b and 101c on both sides in the connecting direction of the valve blocks 101. Hereinafter, unless otherwise specified, the "housing 10" refers to the housing 10 of the valve block 101a, in which the communication passage 17 is provided.
As shown in FIG. 3, the housing 10 accommodates a pair of unloading valves 40. One of the pair of unloading valves 40 is in another circuit system, other than the circuit system shown in FIG. 1, provided in the fluid pressure system 1000. Because the pair of unloading valves 40 have the similar configurations with each other, the configuration of the one unloading valve 40 will be explained below as an example, and the explanation of the other unloading valve 40 will be omitted as appropriate.
The housing 10 includes: a bottomed accommodating hole 40a that accommodates a spool 41 of the unloading valve 40; the pump passage 11 that opens to the accommodating hole 40a; the tank passage 12 that opens to the accommodating hole 40a; and the load pressure passage 15 that opens to the accommodating hole 40a.
The tank passage 12 has: a first tank passage 12a that communicates with the respective accommodating holes 40a of the pair of unloading valves 40; a second tank passage 12b that communicates with the first tank passage 12a and extends in the connecting direction of the valve blocks 101 (in the direction orthogonal to the plane of the drawing in FIG. 3); and recessed portions 10a that are respectively provided on two mating surfaces 10b and 10c that are in contact with adjacent two other valve blocks 101b and 101c (see FIG. 4). The second tank passage 12b communicates with the respective recessed portions 10a in the two mating surfaces 10b and 10c. The recessed portions 10a respectively open in the mating surfaces 10b and 10c. With such a configuration, the tank passage 12 communicates with the tank passages 12 that are formed in the other valve blocks 101 via the recessed portions 10a in the mating surfaces 10b and 10c. Because the mating surfaces 10b and 10c to the adjacent two other valve blocks 101b and 101c have the same configuration with each other, the illustration of the mating surface 10c and the recessed portion 10a to the valve block 101c will be omitted.
The load pressure passage 15 has: a first load pressure passage 15a that is provided so as to extend substantially perpendicularly to the center axis of the accommodating hole 40a (the spool 41) and opens to the accommodating hole 40a; and a second load pressure passage 15b that is provided so as to extend along the center axis of the accommodating hole 40a and communicates with the first load pressure passage 15a. The first load pressure passage 15a and the second load pressure passage 15b are each a circular hole having a circular cross section. Note that a portion of a load pressure passage 15b that opens to the accommodating hole 40a of the other unloading valve 40 is provided on a cross section different from the cross section shown in FIG. 3. This other load pressure passage 15b extends in the direction orthogonal to the plane of the drawing from the cross section different from the cross section shown in FIG. 3 towards the cross section shown in FIG. 3, and opens to an end surface of the housing 10 on the same cross section as the one load pressure passage 15a (on the cross section shown in FIG. 3). In FIG. 3, the portion provided on the cross section different from the cross section shown in FIG. 3 is shown by broken lines.
The unloading valve 40 has the spool 41 that is movably inserted into the accommodating hole 40a, an unload spring 45 serving as the biasing member that biases the spool 41 towards a bottom portion of the accommodating hole 40a, and a cap 46 that closes the accommodating hole 40a.
A self-pressure chamber 47, into which the self pressure Pps is guided, is formed between one end portion of the spool 41 and the bottom portion of the accommodating hole 40a. A load pressure chamber 48, into which the load pressure Pls is guided, is formed between other end portion of the spool 41 and the cap 46. The unload spring 45 is provided so as to act against the biasing force exerted by the pressure in the self-pressure chamber 47. The spool 41 is moved within the accommodating hole 40a such that the motive force caused by the pressure in the load pressure chamber 48, the motive force caused by the pressure in the self-pressure chamber 47, and the biasing force exerted by the unload spring 45 are balanced.
The spool 41 is formed with: a first self-pressure introducing passage 42a that is formed so as to extend along the axial direction of the spool 41 and that constantly communicates with the self-pressure chamber 47; and a second self-pressure introducing passage 42b that opens at an outer circumferential surface of the spool 41 and communicates with the first self-pressure introducing passage 42a. The second self-pressure introducing passage 42b is formed so as to be constantly in communication with the pump passage 11 opening to the accommodating hole 40a, regardless of the position of the spool 41. Thus, the self pressure Pps is always guided to the self-pressure chamber 47 from the pump passage 11.
In addition, the spool 41 is formed with: a first load-pressure introducing passage 43a that is formed so as to extend along the axial direction of the spool 41 and that constantly communicates with the load pressure chamber 48; and a second load-pressure introducing passage 43b that opens at the outer circumferential surface of the spool 41 and communicates with the first load-pressure introducing passage 43a. The second load-pressure introducing passage 43b is formed so as to be constantly in communication with the load pressure passage 15 opening to the accommodating hole 40a, regardless of the position of the spool 41. Thus, the load pressure Pls is always guided to the load pressure chamber 48 from the load pressure passage 15.
In addition, in the outer circumferential surface of the spool 41, an annular communication groove 44 is formed for controlling the communication between the tank passage 12 and the pump passage 11 in accordance with the position of the spool 41.
When the motive force caused by the self pressure Pps guided to the self-pressure chamber 47 is lower than the combined force of the motive force caused by the load pressure Pls guided to the load pressure chamber 48 and the biasing force exerted by the unload spring 45, the spool 41 abuts against the bottom portion of the accommodating hole 40a, and the unloading valve 40 is in a closed state (the state shown in FIG. 3). In a state in which the unloading valve 40 is closed, the communication between the pump passage 11 and the tank passage 12 through the accommodating hole 40a is shut off by the spool 41.
When the self pressure Pps is increased and the motive force caused by the self pressure Pps becomes higher than the motive force caused by the load pressure Pls and the unload spring 45, the spool 41 is moved against the biasing force exerted by the unload spring 45. As a result, the unloading valve 40 is opened, and the pump passage 11 and the tank passage 12 are communicated via the communication groove 44 of the spool 41. Thus, the working oil in the pump passage 11 is guided to the tank passage 12, and the self pressure Pps is lowered accordingly. When the motive force caused by the self pressure Pps becomes lower than the motive force caused by the load pressure Pls and the unload spring 45, the unloading valve 40 is closed by the biasing force exerted by the unload spring 45.
In addition, the housing 10 is formed with a pair of communication passages 17a and 17b. Each of the communication passages 17a and 17b is formed solely by a single through-hole that extends linearly along the connecting direction of the valve blocks 101. Each through-hole opens at both of the mating surfaces 10b and 10c to other valve blocks 101 of the housing 10 by communicating with the recessed portions 10a. With such a configuration, the communication passages 17a and 17b communicate with the tank passage 12 by respectively having both ends communicating with the recessed portion 10a.
The one communication passage 17a is provided in the hydraulic circuit system shown in FIG. 1. The other communication passage 17b is provided in another hydraulic circuit system in which the other unloading valve 40 is provided. Because the configurations of the pair of communication passages 17a and 17b are the same with each other, in the following, only the detailed explanation of the communication passage 17a in the hydraulic circuit system shown in FIG. 1 will be provided, and the explanation of the other communication passage 17b will be omitted.
A portion of the communication passage 17a is located adjacent to the first load pressure passage 15a of the load pressure passage 15 such that the portion is separated from the first load pressure passage 15a only by a wall portion of the housing 10 without any other passage for guiding the working oil interposed therebetween. Specifically, when viewed in a certain plane that is parallel to the center axis of either the first load pressure passage 15a or the communication passage 17a (for example, in a plan view parallel to the center axis of the first load pressure passage 15a as seen from the direction of the arrow A in FIG. 3), in the portion where the first load pressure passage 15a and the communication passage 17a intersect (the portion B with cross-hatching in FIG. 3), no passage or other hydraulic equipment is provided, and only the wall portion of the housing 10 is provided. Furthermore, the imaginary line connecting the center axis of the first load pressure passage 15a and the center axis of the communication passage 17 in the shortest distance (in other words, the common perpendicular line between the center axes that coincides with a line C in FIG. 3) does not intersect with any other passage or hydraulic equipment and only intersect with the wall portion of the housing 10.
In the following, operational advantages of the valve device 100 will be described.
In this embodiment, by driving the pump P by setting the control valve 20 at the neutral position 20C, a warming-up operation can be performed. As a result, the relief valve 30 is opened, and the working oil discharged by the pump P is circulated by being returned to the tank T through the pump passage 11, the relief valve 30, and the tank passage 12 and by being sucked again by the pump P, and thus, the temperature of the circulating working oil (the working oil in the tank T) is increased. In addition, because both ends of the communication passage 17a communicate with the tank passage 12, the temperature of the working oil in the communication passage 17a is also increased.
In the above, because the load pressure passage is provided to guide the load pressure serving as the signal pressure, the load pressure passage is configured so as to communicate with the tank passage via the restrictor and such that the flow amount returned to the tank is relatively limited, making the pressure less likely to be decreased. In other words, relative to any other passage, such as the pump passage and the tank passage, the flow of the working oil is relatively limited in the load pressure passage. Therefore, the working oil that has been warmed by the warming-up operation is less likely to be guided to the load pressure passage. If the temperature of the working oil in the load pressure passage is low, and if there is a temperature difference from the temperature of the working oil in the pump passage (the self pressure), there is a risk in that the responsiveness for the capacity control of the pump is deteriorated, potentially causing hunting.
In contrast, in this embodiment, the communication passage 17a, in which the internal working oil flowing therein has been warmed, is arranged adjacent to the load pressure passage 15 such that the communication passage 17a and the load pressure passage 15 are separated only by the wall portion of the housing 10 without any other passage interposed therebetween. The temperature of the working oil in the communication passage 17a is transferred to the working oil in the load pressure passage 15 via the wall portion of the housing 10, and thereby, the working oil in the load pressure passage 15 is warmed. As a result, the cause of the temperature difference between the working oil at the self pressure Pps and the working oil at the load pressure Pls is suppressed, and it is possible to improve the responsiveness for the capacity control of the pump P.
It is desirable to form the communication passage 17a such that the portion thereof adjacent to the load pressure passage 15 is formed closer to the load pressure passage 15 to an extent that durability can be ensured. However, the communication passage 17a may be arranged such that the portion thereof adjacent to the load pressure passage 15 may also be spaced from the load pressure passage 15 to an extent that allows the working oil in the load pressure passage 15 to be warmed.
In addition, in this embodiment, the communication passage 17a only bypasses the tank passage 12 and has no effect on the function of the valve device 100. In other words, according to the this embodiment, it is possible to increase the temperature of the working oil in the load pressure passage 15 without affecting the function of the valve device 100.
In addition, in this embodiment, the communication passage 17a is formed solely by a single straight through-hole whose both ends respectively open at the mating surfaces 10b and 10c of the valve block 101. With such a configuration, it is possible to form the communication passage 17a with ease.
Next, modifications of present embodiment will be described. The following modifications also fall within the scope of the present invention, and it is also possible to combine the configurations shown in the modifications with the configurations described in the above embodiment, or to combine the configurations described in the following different modifications with each other.
In the above embodiment, the communication passage 17 is provided in the valve block 101a, in which the unloading valve 40 is provided, in the valve device 100 for controlling the communication of the hydraulic cylinder 1 with the pump P and the tank T. In contrast, the communication passage 17 may be provided in the control mechanism 110 for controlling the discharge capacity of the pump P. Specifically, the communication passage 17 may also be provided in the regulator 111 or the control actuator 112. In this case, a housing (not shown) of the control mechanism 110 may be separate from or integral with a pump housing of the pump P or the housing 10 of the valve device 100. In other words, the fluid pressure apparatus may be the control mechanism 110 (the regulator 111 or the control actuator 112) that controls the discharge capacity of the pump P.
In addition, the control mechanism 110 may be configured such that the regulator 111 is not included and such that the self pressure Pps of the pump P and the load pressure Pls of the hydraulic cylinder 1 are guided directly to the control actuator 112, and the control actuator 112 is driven directly by the differential pressure between the self pressure Pps and the load pressure Pls.
In addition, in the above-described embodiment, the communication passage 17 is a single through-hole that opens at the mating surfaces 10b and 10c of the housing 10. In contrast, as long as the communication passage 17 communicates with the tank passage 12, the communication passage 17 may be configured of a plurality of holes, and the communication passage 17 may also be configured to communicate with the tank passage 12 at places other than the recessed portions 10a in the mating surfaces 10b and 10c.
In addition, in the above-described embodiment, in the valve device 100, the communication passage 17 is provided in the one valve block 101a having the other valve blocks 101b and 101c on its both sides in the connecting direction. In other words, the valve device 100 has three valve blocks 101, namely, the valve block 101a, in which the communication passage 17 is provided, and two valve blocks 101b and 101c that are adjacent to the valve block 101a on both sides thereof in the connecting direction. Further, as in the above-described embodiment, other valve blocks 101 (two valve blocks in the above-described embodiment) may further be connected to these three valve blocks 101a, 101b, and 101c. For such a configuration, the communication passage 17 may be provided in the valve block 101 that is provided at the end in the connecting direction. In addition, the communication passage 17 may be provided in the valve device 100 that is formed of two valve blocks 101 or a single valve block 101 (monoblock). In other words, the number of the valve blocks 101 can be any number.
The configurations, operations, and effects of the embodiment of the present invention will be collectively described below.
The fluid pressure system 1000 includes the variable displacement pump P and the valve device 100 serving as the fluid pressure apparatus. The valve device 100 includes the housing 10 including the load pressure passage 15 configured to guide the load pressure Pls to the variable displacement pump P, the variable displacement pump P being configured such that the discharge capacity is controlled in accordance with the self pressure Pps discharged by the variable displacement pump P and the load pressure Pls supplied, wherein the housing 10 further includes: the pump passage 11 configured to guide the working oil sucked from the tank T and discharged by the pump P; the tank passage 12 configured to return the working oil discharged by the pump P to the tank T; and the communication passage 17 having both ends communicating with the tank passage 12, and wherein at least a potion of the communication passage 17 is arranged adjacent to the load pressure passage 15 such that the portion is separated from the load pressure passage 15 only by the wall portion of the housing 10 without any other passage guiding the working oil interposed between the portion and the load pressure passage 15.
In this configuration, the working oil, which is guided to the tank passage 12 by being sucked from the tank T and discharged by the pump P, is warmed by the warming-up operation. Therefore, the working fluid in the communication passage 17, which communicates with the tank passage 12, also becomes a warmed working oil. Because at least a potion of the communication passage 17 is arranged adjacent to the load pressure passage 15 with no other passage provided between them, at the adjacent portion, the heat of the working oil in the communication passage 17 is transferred to the load pressure passage 15. Thus, it is possible to warm the working oil in the load pressure passage 15. Therefore, it is possible to improve the responsiveness of the capacity control of the pump P.
In addition, the valve device 100 controls the communication of the pump P and the tank T with the hydraulic cylinder 1 and has three valve blocks 101 that are connected to in a predetermined direction. The valve blocks 101 each has the independent housing 10. The communication passage 17, in the one valve block 101a, has the through-hole, the through-hole opening at each of the mating surfaces 10b and 10c to the housings 10 of the two valve blocks 101b and 101c, both of which are adjacent to the one valve block 101a.
In this configuration, by forming the through-hole in the mating surfaces 10b and 10c to the valve blocks 101b and 101c adjacent to the valve block 101a, it is possible to form the communication passage 17 with ease.
Embodiments of the present invention were described above, but the above embodiments are merely examples of applications of the present invention, and the technical scope of the present invention is not limited to the specific constitutions of the above embodiments.
With respect to the above description, the contents of application No. 2022-158429, with a filing date of September 30, 2022 in Japan , are incorporated herein by reference.

Claims

A fluid pressure apparatus comprising a housing provided with a signal pressure passage configured to guide a signal pressure to a variable displacement pump, the variable displacement pump being configured such that a discharge capacity is controlled in accordance with a self pressure discharged by the variable displacement pump and the signal pressure supplied, wherein
the housing is further provided with:
a pump passage configured to guide a working fluid sucked from a tank and discharged by the pump;

a tank passage configured to return the working fluid discharged by the pump to the tank; and

a communication passage having both ends communicating with the tank passage, and wherein

at least a potion of the communication passage is arranged adjacent to the signal pressure passage such that the potion is separated from the signal pressure passage only by a wall portion of the housing without any other passage guiding working fluid interposed between the potion and the signal pressure passage.
The fluid pressure apparatus according to claim 1, wherein
the fluid pressure apparatus is a valve device configured to control communication of the pump and the tank with a fluid pressure actuator, the valve device having three valve blocks connected in a predetermined direction,

the valve blocks each has the housing in an independent manner, and

the communication passage has a through-hole in one of the valve blocks, the through-hole opening at each of mating surfaces of the one of the valve blocks, the mating surfaces being in contact with the housings of two of the valve blocks adjacent to the one of the valve blocks.
A fluid pressure system comprising:
a variable displacement pump configured such that a discharge capacity is controlled in accordance with a self pressure discharged by the variable displacement pump and a signal pressure supplied; and

a fluid pressure apparatus having a housing provided with a signal pressure passage, the signal pressure passage being configured to guide the signal pressure to the pump, wherein

the housing of the fluid pressure apparatus is further provided with:
a pump passage configured to guide a working fluid sucked from a tank and discharged by the pump;

a tank passage configured to return the working fluid discharged by the pump to the tank; and

a communication passage having both ends communicating with the tank passage, and wherein

at least a potion of the communication passage is arranged adjacent to the signal pressure passage such that the potion is separated from the signal pressure passage only by a wall portion of the housing without any other passage guiding working fluid interposed between the potion and the signal pressure passage.