EP4692564A1

EP4692564A1 - Fluid pressure circuit

Info

Publication number: EP4692564A1
Application number: EP24780384.4A
Authority: EP
Inventors: Yoshiyuki Shimada
Original assignee: Eagle Industry Co Ltd
Current assignee: Eagle Industry Co Ltd
Priority date: 2023-03-30
Filing date: 2024-03-26
Publication date: 2026-02-11
Also published as: CN120981665A; WO2024204276A1; JPWO2024204276A1

Abstract

There is provided a fluid pressure circuit capable of obtaining a pressure-increased fluid suitable for the situation. A fluid pressure circuit 101 includes a fluid supply device 2 that delivers a primary fluid; and a pressure increasing device 30 configured for increasing a pressure of a secondary fluid in output chambers 30-4 and 30-6 using the primary fluid input from the fluid supply device 2 to an input chamber 30-3, and delivering the secondary fluid to a supply destination 7. The pressure increasing device 30 is configured such that the output chambers 30-4 and 30-6 include a plurality of pressure receiving surfaces 121a and 122a and a pressure increase ratio of the secondary fluid to the primary fluid is changeable.

Description

{TECHNICAL FIELD}

The present invention relates to a fluid pressure circuit, particularly to a fluid pressure circuit including a pressure increasing device for increasing the pressure of a working fluid.

{BACKGROUND ART}

Fluid pressure circuits, each of which drives an actuator using a working fluid such as hydraulic oil delivered from a fluid supply device such as a pump, are known in various fields. Among such fluid pressure circuits, there are fluid pressure circuits in which the pressure increasing device capable of delivering the working fluid that is increased in pressure actuates the actuator or enables an accumulator to store pressure.
For example, a fluid pressure circuit that actuates a hydraulic cylinder such as a bucket in a hydraulic excavator using a working fluid that is increased in pressure by a pressure increasing device is known (see Patent Citation 1). A fluid pressure circuit illustrated in FIG. 5, which is one example of such a fluid pressure circuit, is mainly composed of a drive mechanism 501, a hydraulic pump 502, an electromagnetic direction switching valve 503 (hereinafter, referred to as the direction switching valve 503), a pressure increasing device 505, an accumulator 506, a hydraulic pressure-supplied circuit 507 to which a hydraulic cylinder and the like is connected, a tank 508, and a controller 509.
The direction switching valve 503 is a spring center type three-position, four-port electromagnetic switching valve. When the direction switching valve 503 is in a neutral position 503-1, oil discharged from the hydraulic pump 502 is discharged into the tank 508.
When an electrical signal from the controller 509 is applied to a solenoid 503a of the direction switching valve 503 through an electrical signal line 510, and the solenoid 503a is energized, the direction switching valve 503 switches from the neutral position 503-1 to a right position 503-2. As a result, the oil discharged from the hydraulic pump 502 is supplied to an input chamber 505-3 of the pressure increasing device 505. In addition, the oil in an oil chamber 505-5 of the pressure increasing device 505 is discharged into the tank 508.
The pressure increasing device 505 is composed of a casing 505-1 and a piston 505-2. The piston 505-2 includes a large-diameter portion 520 and a small-diameter portion 521, and is enclosed in the casing 505-1 so as to be slidable in an axial direction. According to the so-called Pascal's principle, in the pressure increasing device 505, the area ratio of a pressure receiving area S51 of the large-diameter portion 520 to a pressure receiving area S52 of the small-diameter portion 521 is the pressure increase ratio of an output pressure P52 of an output chamber 505-4 to an input pressure P51 of the input chamber 505-3. As a result, the following Formula 1 is established. $\begin{array}{l} P 51 \times S 51 = P 52 \times S 52 \\ ∴ P 52 = P 51 \times S 51 / S 52 \end{array}$
As the input pressure P51 of the input chamber 505-3 increases, the piston 505-2 moves to the left, namely, to an output chamber 505-4 side. The oil in the output chamber 505-4 that is increased in pressure accordingly is delivered to the accumulator 506 or the hydraulic pressure-supplied circuit 507.
In addition, when an electrical signal from the controller 509 is applied to a solenoid 503b of the direction switching valve 503 through an electrical signal line 511, and the solenoid 503b is energized, the direction switching valve 503 switches from the right position 503-2 to a left position 503-3. As a result, the oil discharged from the hydraulic pump 502 is supplied to the oil chamber 505-5 of the pressure increasing device 505. In addition, the oil in the input chamber 505-3 is discharged into the tank 508.
As the pressure in the oil chamber 505-5 increases, the piston 505-2 moves to the right, namely, to an input chamber 505-3 side. The pressure in the output chamber 505-4 becomes relatively negative accordingly, and the oil in the tank 508 is suctioned into the output chamber 505-4.

{CITATION LIST}

{Patent Literature}

Patent Citation 1: JP 2011-185417 A (Page 7, FIG. 1)

{SUMMARY OF INVENTION}

{Technical Problem}

In the fluid pressure circuit as illustrated in FIG. 5, by alternately switching the direction switching valve 503 between the right position 503-2 and the left position 503-3, the piston 505-2 is repeatedly reciprocatable to continuously deliver the oil that is increased in pressure.
In the fluid pressure circuit as illustrated in FIG. 5, the pressure increase ratio is constant, and when the input pressure from the pump is low, in order to obtain a predetermined discharge pressure, the pressure increase ratio needs to be increased, whereas when the input pressure from the pump is high, the pressure increase ratio needs to be decreased. In addition, a desired effect cannot be obtained for the case where the input pressure fluctuates. Namely, if a pressure increasing device with a high pressure increase ratio is installed to match a state where the input pressure is low, the amount of oil discharged decreases when the input pressure is high, and conversely, if a pressure increasing device with a low pressure increase ratio is installed to match a state where the input pressure is high, the pressure cannot increase to a predetermined pressure or higher when the input pressure is low.
The present invention has been made in view of such problems, and an object of the present invention is to provide a fluid pressure circuit capable of obtaining a pressure-increased fluid suitable for the situation.

{Solution to Problem}

In order to solve the foregoing problems, a fluid pressure circuit according to the present invention is a fluid pressure circuit including: a fluid supply device that delivers a primary fluid; and a pressure increasing device configured for increasing a pressure of a secondary fluid in an output chamber using the primary fluid input from the fluid supply device to an input chamber, and delivering the secondary fluid to a supply destination, wherein the pressure increasing device is configured such that at least one of the input chamber and the output chamber includes a plurality of pressure receiving surfaces and a pressure increase ratio of the secondary fluid to the primary fluid is changeable. According to the aforesaid feature of the present invention, the fluid pressure circuit can obtain the desired pressure-increased fluid by changing the pressure increase ratio according to an input pressure, can obtain the desired pressure-increased fluid even when the input pressure fluctuates, and can obtain the pressure-increased fluid for various pressure values supplied to the pressure increasing device, so that a circuit without waste of energy can be achieved.
It may be preferable that the fluid pressure circuit is configured to change the pressure increase ratio by selectively switching between the plurality of pressure receiving surfaces. According to this preferable configuration, the fluid pressure circuit can improve the responsiveness of control to changes in the situation.
It may be preferable that the fluid pressure circuit further includes a pressure sensor that detects a pressure of the primary fluid. According to this preferable configuration, the pressure increase ratio can be changed in response to the pressure of the primary fluid. Therefore, the fluid pressure circuit can improve the accuracy of control to changes in the situation.
It may be preferable that the output chamber has output spaces, each of the spaces being for each of the pressure receiving surfaces. According to this preferable configuration, the fluid pressure circuit can set a plurality of pressure increase ratios with a simple configuration.
It may be preferable that the fluid pressure circuit is configured to change the pressure increase ratio by increasing or decreasing the number of the output spaces connected to the supply destination. According to this preferable configuration, the fluid pressure circuit can connect or disconnect another output space to or from the current supply destination while keeping the output space, which is connected to the current supply destination, connected to the supply destination. As a result, the fluid pressure circuit can change the pressure increase ratio while maintaining smooth delivery of the working fluid from the pressure increasing device to the supply destination.
It may be preferable that, the fluid pressure circuit further includes an output switching valve disposed between the supply destination and at least one of the output spaces. According to this preferable configuration, the fluid pressure circuit can, with simple control, select the output space according to the pressure increase ratio, and enables the output space to communicate with the supply destination.
It may be preferable that the input chamber has input spaces, each of the input spaces being for each of the pressure receiving surfaces. According to this preferable configuration, the fluid pressure circuit can set a plurality of pressure increase ratios with a simple configuration.
It may be preferable that the fluid pressure circuit is configured to change the pressure increase ratio by increasing or decreasing the number of the input spaces connected to the fluid supply device. According to this preferable configuration, the fluid pressure circuit can connect or disconnect another input space to or from the current supply destination while keeping the input space, which is connected to the current supply destination, connected to the fluid supply device. As a result, the fluid pressure circuit can change the pressure increase ratio while maintaining smooth delivery of the working fluid from the pressure increasing device to the supply destination.
It may be preferable that the fluid pressure circuit further includes an input switching valve disposed between the fluid supply device and at least one of the input spaces. According to this preferable configuration, the fluid pressure circuit can, with simple control, select the input space according to the pressure increase ratio, and enables the input space to communicate with the supply destination.

{BRIEF DESCRIPTION OF DRAWINGS}

FIG. 1 is a schematic view illustrating a fluid pressure circuit according to a first embodiment of the present invention.
FIG. 2 is a schematic view illustrating a fluid pressure circuit according to a second embodiment of the present invention.
FIG. 3 is a schematic view illustrating a fluid pressure circuit according to a third embodiment of the present invention.
FIG. 4 is a schematic view illustrating a fluid pressure circuit according to a fourth embodiment of the present invention.
FIG. 5 is a schematic view illustrating a conventional fluid pressure circuit.

{DESCRIPTION OF EMBODIMENTS}

Modes for implementing a fluid pressure circuit according to the present invention will be described below based on embodiments.

{First embodiment}

A fluid pressure circuit according to a first embodiment of the present invention will be described with reference to FIG. 1. In the following description, the left and right sides of FIG. 1 as viewed from the front correspond to the valve position of an electromagnetic direction switching valve and the left and right sides of a pressure increasing device.
A hydraulic circuit serving as the fluid pressure circuit according to the first embodiment increases the pressure of oil serving as a secondary fluid in response to an operation command in a work machine, a construction machine, a loading and unloading vehicle, an automobile, or the like, and delivers the oil to a hydraulic cylinder that actuates a bucket.
As illustrated in FIG. 1, a hydraulic circuit 101 is mainly composed of a drive mechanism 1, a hydraulic pump 2, an electromagnetic direction switching valve 3 (hereinafter, referred to as the direction switching valve 3), a relief valve 4, an accumulator 6, a hydraulic pressure-supplied circuit 7 serving as a supply destination, a tank 8, a controller 9, a pressure increasing device 30, an electromagnetic switching valve 31 serving as an output switching valve, a pressure sensor 32, electrical signal lines 10, 11, 33, and 34, check valves 12, 13, 36, 38, and 41, and pipelines 14 to 22, 35, 37, 39, and 40.
The hydraulic pump 2 is coupled to the drive mechanism 1 such as an internal combustion engine, and is rotated by power from the drive mechanism 1 to supply pressure oil serving as a primary fluid to a downstream side. The pressure oil delivered from the hydraulic pump 2 passes through the pipeline 14, and flows into the direction switching valve 3.
Incidentally, the hydraulic pump 2 of the present embodiment is of a fixed capacity type, but may be of a variable capacity type. In addition, the hydraulic pump 2 may be a drive unit including a hydraulic cylinder and the like instead of a pump, and may have a structure in which return oil from the hydraulic cylinder is delivered to the direction switching valve 3. Namely, the structure may be such that the pressure of the fluid supplied to the pressure increasing device fluctuates.
The direction switching valve 3 is a spring center type three-position, four-port electromagnetic switching valve. The direction switching valve 3 in a neutral position 3-1 connects the pipeline 14 to the pipeline 15. The pipeline 15 is connected to the tank 8. Therefore, the entire amount of the pressure oil delivered from the hydraulic pump 2 is discharged to the tank 8.
The direction switching valve 3 includes solenoids 3a and 3b. The solenoids 3a and 3b are electrically connected to the controller 9 through electrical signal lines 10 and 11.
When an operation command is input from a control device (not illustrated), the controller 9 outputs an electrical signal to the electrical signal line 10 or the electrical signal line 11, and starts controlling the direction switching valve 3. Incidentally, the operation command is not limited to being input from the control device, and may be, for example, an electrical signal output in response to the operation of a lever, and may be changed as appropriate.
When an electrical signal is applied to the solenoid 3a of the direction switching valve 3 through the electrical signal line 10, and the solenoid 3a is energized, a spool moves in a left direction, and the direction switching valve 3 switches to a right position 3-2. The direction switching valve 3 in the right position 3-2 connects the pipeline 14 to the pipeline 16, and connects the pipeline 15 to the pipeline 17.
The pipeline 16 is connected to a port Ph1 of the pressure increasing device 30. The pipeline 17 is connected to a port Pr1 of the pressure increasing device 30. The pressure oil delivered from the hydraulic pump 2 is supplied from the port Ph1 to an input chamber 30-3. In addition, the oil in an oil chamber 30-5 is discharged to the tank 8 from the port Pr1.
When an electrical signal is applied to the solenoid 3b of the direction switching valve 3 through the electrical signal line 11, and the solenoid 3b is energized, a spool moves in a right direction, and the direction switching valve 3 switches to a left position 3-3. The direction switching valve 3 in the left position 3-3 connects the pipeline 14 to the pipeline 17, and connects the pipeline 15 to the pipeline 16.
The pressure oil delivered from the hydraulic pump 2 is supplied from the port Pr1 to the oil chamber 30-5. In addition, the oil in the input chamber 30-3 is discharged to the tank 8 from the port Ph1.
A pipeline 21 is branched off and connected to the pipeline 14 between the hydraulic pump 2 and the direction switching valve 3. The pipeline 21 is communicably connected to the pipeline 22 with the relief valve 4 interposed therebetween. The pipeline 22 is connected to the tank 8.
The pressure sensor 32 is connected to the pipeline 16 between the direction switching valve 3 and the port Ph1. The pressure sensor 32 is electrically connected to the controller 9 through the electrical signal line 33. The pressure sensor 32 detects the hydraulic pressure in the pipeline 16, and outputs a pressure signal capable of specifying the hydraulic pressure to the electrical signal line 33.
The pressure increasing device 30 is mainly composed of a casing 30-1 and a piston 30-2.
The casing 30-1 is formed in a stepped cylindrical shape including a large-diameter cylindrical portion 110, a small-diameter cylindrical portion 111, and a medium-diameter cylindrical portion 112. The large-diameter cylindrical portion 110, the medium-diameter cylindrical portion 112, and the small-diameter cylindrical portion 111 are disposed in order from the right side to the left side.
The large-diameter cylindrical portion 110 is formed in a cylindrical shape with a bottom and a top which includes a peripheral wall, a circular plate, and an annular plate. Incidentally, in the present embodiment, for convenience of description, the circular plate disposed on the right side is referred to as the bottom, and the annular plate disposed on the left side is referred to as the top; however, the circular plate and the annular plate may be referred to as the top and the bottom, respectively. The same applies to the description of the small-diameter cylindrical portion 111 and the medium-diameter cylindrical portion 112.
The port Pr1 penetrating through the peripheral wall of the large-diameter cylindrical portion 110 in a radial direction is provided at a left end of the peripheral wall. The port Ph1 penetrating through the circular plate of the large-diameter cylindrical portion 110 in the axial direction is provided at the radial center of the circular plate.
The small-diameter cylindrical portion 111 is formed in a cylindrical shape with a top which includes a peripheral wall and a circular plate. The small-diameter cylindrical portion 111 has a smaller diameter than the large-diameter cylindrical portion 110.
A port Pt1 penetrating through the peripheral wall of the small-diameter cylindrical portion 111 in the radial direction is provided at a left end of the peripheral wall. A port Ps1 penetrating through the circular plate of the small-diameter cylindrical portion 111 in the axial direction is provided at the radial center of the circular plate.
The medium-diameter cylindrical portion 112 is formed in a cylindrical shape with a top which includes a peripheral wall and an annular plate. The medium-diameter cylindrical portion 112 has a diameter smaller than that of the large-diameter cylindrical portion 110 and larger than that of the small-diameter cylindrical portion 111.
Ports Ps2 and Pt2 penetrating through the annular plate of the medium-diameter cylindrical portion 112 in the axial direction are provided at positions spaced apart from each other in a circumferential direction.
The large-diameter cylindrical portion 110, the small-diameter cylindrical portion 111, and the medium-diameter cylindrical portion 112 are formed such that the respective axes are disposed on substantially the same straight line.
The piston 30-2 is formed in a stepped columnar shape including a large-diameter columnar portion 120, a small-diameter columnar portion 121, and a medium-diameter columnar portion 122. The large-diameter columnar portion 120, the medium-diameter columnar portion 122, and the small-diameter columnar portion 121 are disposed in order from right to left.
The diameter of the large-diameter columnar portion 120 is very slightly smaller than the inner diameter of the large-diameter cylindrical portion 110 of the casing 30-1. The large-diameter columnar portion 120 is slidable along an inner peripheral surface of the peripheral wall of the large-diameter cylindrical portion 110.
The diameter of the small-diameter columnar portion 121 is very slightly smaller than the inner diameter of the small-diameter cylindrical portion 111 of the casing 30-1. The small-diameter columnar portion 121 is slidable along an inner peripheral surface of the peripheral wall of the small-diameter cylindrical portion 111. In addition, a cross-sectional area S2 of the small-diameter columnar portion 121 is smaller than a cross-sectional area S1 of the large-diameter columnar portion 120 (S2 < S1).
The diameter of the medium-diameter columnar portion 122 is very slightly smaller than the inner diameter of the medium-diameter cylindrical portion 112 of the casing 30-1. The medium-diameter columnar portion 122 is slidable along an inner peripheral surface of the peripheral wall of the medium-diameter cylindrical portion 112. In addition, a cross-sectional area S3 of the medium-diameter columnar portion 122 is smaller than the cross-sectional area S1 of the large-diameter columnar portion 120 and is larger than the cross-sectional area S2 of the small-diameter columnar portion 121 (S2 < S3 < S1).
The large-diameter columnar portion 120, the small-diameter columnar portion 121, and the medium-diameter columnar portion 122 are formed such that the respective axes are disposed on substantially the same straight line.
By enclosing the piston 30-2 in the casing 30-1, the input chamber 30-3 defining one input space, a small-diameter output chamber 30-4 defining one output space, the oil chamber 30-5, and a medium-diameter output chamber 30-6 defining one output space are formed in the pressure increasing device 30.
The output chamber of the present invention includes the small-diameter output chamber 30-4 and the medium-diameter output chamber 30-6, and the input chamber of the present invention includes the input chamber 30-3.
The input chamber 30-3 is formed by an inner surface of the large-diameter cylindrical portion 110 of the casing 30-1 and a right end surface 120a of the large-diameter columnar portion 120 of the piston 30-2. The input chamber 30-3 communicates with the port Ph1.
The right end surface 120a having a circular shape is a pressure receiving surface on which a pressure P1 in the input chamber 30-3 acts. A pressure receiving area of the right end surface 120a is the same as the cross-sectional area S1 of the large-diameter columnar portion 120. Hereinafter, the right end surface 120a is referred to as the pressure receiving surface 120a, and the pressure receiving area thereof is referred to as the pressure receiving area S1.
The small-diameter output chamber 30-4 is formed by an inner surface of the small-diameter cylindrical portion 111 of the casing 30-1 and a left end surface 121a of the small-diameter columnar portion 121 of the piston 30-2. The small-diameter output chamber 30-4 communicates with the ports Ps1 and Pt1.
The left end surface 121a having a circular shape is a pressure receiving surface on which a pressure P2 in the small-diameter output chamber 30-4 acts. A pressure receiving area of the left end surface 121a is the same as the cross-sectional area S2 of the small-diameter columnar portion 121. Hereinafter, the left end surface 121a is referred to as the pressure receiving surface 121a, and the pressure receiving area thereof is referred to as the pressure receiving area S2.
The oil chamber 30-5 is formed by the inner surface of the large-diameter cylindrical portion 110 of the casing 30-1, a left end surface of the large-diameter columnar portion 120 of the piston 30-2, and an outer peripheral surface of the medium-diameter columnar portion 122 of the piston 30-2. The oil chamber 30-5 communicates with the port Pr1.
The medium-diameter output chamber 30-6 is formed by the medium-diameter cylindrical portion 112 of the casing 30-1, a left end surface 122a of the medium-diameter columnar portion 122 of the piston 30-2, and an outer peripheral surface of the small-diameter columnar portion 121. The medium-diameter output chamber 30-6 communicates with the ports Ps2 and Pt2.
The left end surface 122a having an annular shape is a pressure receiving surface on which a pressure P3 in the medium-diameter output chamber 30-6 acts. A pressure receiving area of the left end surface 122a is the same as a difference between the cross-sectional area S3 of the medium-diameter columnar portion 122 and the cross-sectional area S2 of the small-diameter columnar portion 121 (S3 - S2). Hereinafter, the left end surface 122a is referred to as the pressure receiving surface 122a, and the pressure receiving area thereof is referred to as the pressure receiving area (S3 - S2).
The port Ps1 is connected to the pipeline 18. The pipeline 18 is connected to the hydraulic pressure-supplied circuit 7, and the pipeline 19 is connected between the port Ps1 and the hydraulic pressure-supplied circuit 7. In addition, the check valve 13 is provided in the pipeline 18 between the port Ps1 and the pipeline 19. The check valve 13 is configured to allow the oil serving as the secondary fluid to pass therethrough from the port Ps1 to a hydraulic pressure-supplied circuit 7 side.
The port Pt1 is connected to the pipeline 20. The pipeline 20 is connected to the pipeline 15, and the check valve 12 is provided between the port Pt1 and the pipeline 15. The check valve 12 is configured to allow the oil serving as the secondary fluid to pass therethrough from a tank 8 side to the port Pt1.
As will be described later, by opening the check valve 13, the oil delivered from the small-diameter output chamber 30-4 through the port Ps1 passes through the pipeline 18, and is delivered to the accumulator 6 or the hydraulic pressure-supplied circuit 7. Meanwhile, when the oil is delivered from the small-diameter output chamber 30-4, the check valve 12 is in a closed state, so that the oil is prevented from being delivered from the port Pt1 to the tank 8 side.
In addition, as will be described later, when the pressure in the small-diameter output chamber 30-4 becomes relatively negative, the check valve 12 is opened, and the oil in the tank 8 is suctioned into the small-diameter output chamber 30-4 through the pipelines 15 and 20. Meanwhile, when the pressure in the small diameter output chamber 30-4 is a relatively negative pressure, the check valve 13 is in a closed state, so that the oil is prevented from being suctioned into the small-diameter output chamber 30-4 from the accumulator 6 or the hydraulic pressure-supplied circuit 7 side.
The port Ps2 is connected to the pipeline 35. The pipeline 35 is connected to the electromagnetic switching valve 31, and the check valve 36 is provided between the port Ps2 and the electromagnetic switching valve 31. The check valve 36 is configured to allow the oil serving as the secondary fluid to pass therethrough from the port Ps2 to the electromagnetic switching valve 31.
The port Pt2 is connected to the pipeline 40. The pipeline 40 is connected to the pipeline 15, and the check valve 41 is provided between the port Pt2 and the pipeline 15. The check valve 41 is configured to allow the oil serving as the secondary fluid to pass therethrough from the tank 8 side to the port Pt2.
As will be described later, when the pressure in the medium-diameter output chamber 30-6 becomes relatively negative, the check valve 41 is opened, and the oil in the tank 8 is suctioned into the medium-diameter output chamber 30-6 through the pipelines 15 and 40. Meanwhile, when the pressure in the medium-diameter output chamber 30-6 is a relatively negative pressure, the check valve 36 is in a closed state, so that the oil is prevented from being suctioned into the medium-diameter output chamber 30-6 from an electromagnetic switching valve 31 side to be described later.
The piston 30-2 enclosed in the casing 30-1 is reciprocatable between a starting end position and a terminal end position.
The starting end position in the present embodiment is a position where the pressure receiving surface 120a of the large-diameter columnar portion 120 of the piston 30-2 comes into contact with a stopper 110a provided at a right end on a radial inner side of the large-diameter cylindrical portion 110 of the casing 30-1. As a result, a space in the input chamber 30-3 that communicates with the port Ph1 is ensured.
Incidentally, the structure for ensuring the space in the input chamber 30-3 that communicates with the port Ph1 may be implemented, for example, by recessing the pressure receiving surface of the large-diameter columnar portion, and may be changed as appropriate as long as the primary fluid can flow smoothly into the input chamber. In addition, if a direction in which the piston moves and a direction in which the primary fluid flows in are the same as illustrated in FIG. 1, the piston in the starting end position may close the port Ph1. The same applies to the terminal end position.
The terminal end position in the present embodiment is a position where the pressure receiving surface 122a of the medium-diameter columnar portion 122 of the piston 30-2 comes into contact with a top surface 112a of the medium-diameter cylindrical portion 112 of the casing 30-1.
Here, when the piston 30-2 is in the starting end position, the medium-diameter output chamber 30-6 has a shorter axial dimension than the small-diameter output chamber 30-4 and the oil chamber 30-5. Therefore, when the piston 30-2 is in the terminal end position, the left end surface of the large-diameter columnar portion 120 of the piston 30-2 is spaced apart from a top surface of the large-diameter cylindrical portion 110 of the casing 30-1. Similarly, the pressure receiving surface 121a of the small-diameter columnar portion 121 of the piston 30-2 is spaced apart from a top surface of the small-diameter cylindrical portion 111 of the casing 30-1.
In this manner, a space in the oil chamber 30-5 that communicates with the port Pr1 and a space in the small-diameter output chamber 30-4 that communicates with the ports Ps1 and Pt1 are ensured.
The electromagnetic switching valve 31 is a spring offset type two-position, three-port electromagnetic switching valve. The electromagnetic switching valve 31 in an offset position 31-1 connects the pipeline 35 to the pipeline 39. The pipeline 39 is connected to the tank 8.
As will be described later, by opening the check valve 36, the oil delivered from the medium-diameter output chamber 30-6 through the port Ps2 passes through the pipelines 35 and 39, and is discharged into the tank 8. Meanwhile, when the oil is delivered from the medium-diameter output chamber 30-6, the check valve 41 is kept in a closed state, so that the oil is prevented from being delivered from the port Pt2 to the tank 8 side.
The electromagnetic switching valve 31 includes a solenoids 31a. The solenoid 31a is electrically connected to the controller 9 through the electrical signal line 34.
When an electrical signal is applied to the solenoid 31a of the electromagnetic switching valve 31 through the electrical signal line 34, and the solenoid 31a is energized, a spool moves and the electromagnetic switching valve 31 switches to an onset position 31-2. The electromagnetic switching valve 31 in the onset position 31-2 connects the pipeline 35 to the pipeline 37, and prevents the pipeline 35 from communicating with the pipeline 39.
The pipeline 37 is connected to the pipeline 19, and the check valve 38 is provided between the electromagnetic switching valve 31 and the pipeline 19. The check valve 38 is configured to allow the oil serving as the secondary fluid to pass therethrough from the electromagnetic switching valve 31 to the pipeline 19.
As will be described later, by opening the check valves 36 and 38, the oil delivered from the medium-diameter output chamber 30-6 through the port Ps2 passes through the pipelines 35 and 37, and is delivered to the pipeline 19.
The pipeline 19 is connected to the accumulator 6 as well as to the pipelines 18 and 37.
The hydraulic pressure-supplied circuit 7 is a hydraulic circuit in which a hydraulic cylinder for operating a bucket or the like is provided.
Next, a pressure increasing cycle by the hydraulic circuit 101 will be described.
First, a state before the pressure increasing device 30 starts increasing the pressure will be described. In this state, the direction switching valve 3 is in the neutral position 3-1, and the electromagnetic switching valve 31 is in the offset position 31-1. In addition, the piston 30-2 is disposed at the starting end position.
The oil is stored in the input chamber 30-3, the small-diameter output chamber 30-4, the oil chamber 30-5, and the medium-diameter output chamber 30-6 of the pressure increasing device 30. The pressures in these chambers are substantially the same as that of the oil serving as the secondary fluid that is stored in the tank 8 open to the outside. In more detail, there are cases where only the pressure in the oil chamber 30-5 is higher than the pressure in the tank 8.
Next, when an operation command is input from the control device (not illustrated), the controller 9 switches the direction switching valve 3 from the neutral position 3-1 to the right position 3-2. As a result, the pressure oil delivered from the hydraulic pump 2 flows into the input chamber 30-3. In addition, the oil in the oil chamber 30-5 is discharged into the tank 8 as the piston 30-2 moves to the left side. Namely, the pressure of the oil in the oil chamber 30-5 is not increased, and the pressure of the oil is substantially constant.
The piston 30-2 moves to the left side when a force F_L1 that moves the piston 30-2 to the left side is larger than a force F_R1 that moves the piston 30-2 to the right side.
In more detail, the force F_L1 is the product of the pressure P1 in the input chamber 30-3 and the pressure receiving area S1 of the pressure receiving surface 120a (F_L1 = P1 × S1). The force F_R1 is the sum of the product of the pressure P2 in the small-diameter output chamber 30-4 and the pressure receiving area S2 of the pressure receiving surface 121a and the product of the pressure P3 in the medium-diameter output chamber 30-6 and the pressure receiving area (S3 - S2) of the pressure receiving surface 122a (F_R1 = P2 x S2 + P3 x (S3 - S2)). Accordingly, the following Formula 2 is established. $P 1 \times S 1 = P 2 \times S 2 + P 3 \times (S 3 - S 2)$
The small-diameter output chamber 30-4 communicates with the hydraulic pressure-supplied circuit 7 side via the check valve 13. In order to deliver the oil serving as the secondary fluid in the small-diameter output chamber 30-4 to the hydraulic pressure-supplied circuit 7 side, the pressure P2 in the small-diameter output chamber 30-4 needs to be increased above a pressure P0 on the hydraulic pressure-supplied circuit 7 side to open the check valve 13 (P0 < P2).
Incidentally, the hydraulic pressure-supplied circuit 7 side refers to a region including the hydraulic pressure-supplied circuit 7 and the accumulator 6, which is located downstream of the check valves 13 and 38 and which has the same pressure P0 as the hydraulic pressure-supplied circuit 7. Incidentally, the pressure P0 is assumed to be constant unless otherwise specified.
Meanwhile, when the electromagnetic switching valve 31 is in the offset position 31-1, the medium-diameter output chamber 30-6 communicates with the tank 8 through both the ports Ps2 and Pt2. As the piston 30-2 moves in the left direction, the oil in the medium-diameter output chamber 30-6 opens the check valve 36, and is discharged into the tank 8 from the port Ps2. Therefore, the oil in the medium-diameter output chamber 30-6 is substantially not compressed.
When the pressure in the tank 8 is zero and the pressures P0 to P2 are relative values with respect to the pressure in the tank 8, the following Formula 3 is established from Formula 2. In addition, the following Formula 4 is established from Formula 3 and a condition formula for opening the check valve 13 (P0 < P2). $P 2 = P 1 \times S 1 / S 2$ $\begin{array}{l} P 0 < P 2 \\ ∴ P 0 < P 1 \times S 1 / S 2 \end{array}$
From Formula 3, when the electromagnetic switching valve 31 is in the offset position 31-1, the pressure increase ratio of the pressure P2 in the small-diameter output chamber 30-4 to the pressure P1 in the input chamber 30-3 is S1/S2.
The piston 30-2 stops when the pressure receiving surface 122a of the piston 30-2 comes into contact with the top surface 112a of the casing 30-1 and the piston 30-2 reaches the terminal end position. At this time, the hydraulic circuit 101 can open the relief valve 4 and discharge the pressure oil into the tank 8 when the pressure in the pipeline 21, in other words, the pressure P1 in the input chamber 30-3 increases to a predetermined level or higher. As a result, the pressure oil delivered from the hydraulic pump 2 can be prevented from being trapped between the hydraulic pump 2 and the input chamber 30-3, so that the circuit can be protected.
When a position sensor (not illustrated) detects that the piston 30-2 has reached the terminal end position, and an electrical signal is input to the controller 9, the controller 9 switches the direction switching valve 3 from the right position 3-2 to the left position 3-3. As a result, the pressure oil in the input chamber 30-3 is discharged into the tank 8, and accordingly, the pressure P1 in the input chamber 30-3 decreases, and becomes substantially the same as the pressure in the tank 8. In addition, the pressure oil delivered from the hydraulic pump 2 flows into the oil chamber 30-5.
Incidentally, the present invention is not limited to the configuration in which the position sensor detects that the piston 30-2 has reached the terminal end position, and the detection method may be realized by pressure detection performed by the pressure sensor 32, a contact sensor that detects that the pressure receiving surface 122a of the piston 30-2 has come into contact with the top surface 112a of the casing 30-1, or the like, and may be changed as appropriate. In addition, timer control may be used, and the configuration may be such that the position of the direction switching valve 3 is switched according to a set time. The same applies to a case where the piston 30-2 has reached the starting end position.
The piston 30-2 moves to the right side as the pressure in the oil chamber 30-5 increases. The oil in the input chamber 30-3 is discharged into the tank 8. Meanwhile, the pressures in the small-diameter output chamber 30-4 and the medium-diameter output chamber 30-6 become relatively negative, and as described above, the oil in the tank 8, which serves as the secondary fluid, is suctioned thereinto. As a result, both the pressure P2 in the small-diameter output chamber 30-4 and the pressure P3 in the medium-diameter output chamber 30-6 become substantially the same as the pressure in the tank 8.
The piston 30-2 stops when the pressure receiving surface 120a of the piston 30-2 comes into contact with the stopper 110a of the casing 30-1 and the piston 30-2 reaches the starting end position. When a position sensor (not illustrated) detects that the piston 30-2 has reached the starting end position, and an electrical signal is input to the controller 9, the controller 9 switches the direction switching valve 3 from the left position 3-3 to the right position 3-2.
In this manner, the controller 9 alternately switches the position of the direction switching valve 3 between the right position 3-2 and the left position 3-3, so that the hydraulic circuit 101 can repeatedly reciprocate the piston 30-2 to continuously deliver the oil, which is increased in pressure, to the hydraulic pressure-supplied circuit 7 side. As a result, the hydraulic circuit 101 can not only supply the oil to the hydraulic pressure-supplied circuit 7 but also store the oil in the accumulator 6.
Next, control when the pressure P0 on the hydraulic pressure-supplied circuit 7 side decreases, for example, due to earth in the bucket being released while the piston 30-2 moves to the left side in a state where the pressure P0 on the hydraulic pressure-supplied circuit 7 side is high will be described.
When the pressure P0 on the hydraulic pressure-supplied circuit 7 side decreases while the piston 30-2 moves to the left side, the pressure P1 in the input chamber 30-3 becomes excessive with respect to the pressure P0.
As a result, the difference between the force F_L1 that moves the piston 30-2 to the left side and the force F_R1 that moves the piston 30-2 to the right side increases (F_R1 <<< F_L1), and the movement speed of the piston 30-2 increases. Accordingly, the change in the volume of the input chamber 30-3 increases rapidly, and the pressure P1 in the input chamber 30-3 becomes relatively small.
When the controller 9 detects from the pressure signal output from the pressure sensor 32 that the pressure P1 has decreased by a predetermined value or more, the controller 9 outputs an electrical signal to the electrical signal line 34 to switch the electromagnetic switching valve 31 to the onset position 31-2.
As described above, the pressure increasing device 30 can open the check valve 13 and deliver the oil in the small-diameter output chamber 30-4 to the hydraulic pressure-supplied circuit 7 side by increasing the pressure P2 in the small-diameter output chamber 30-4 above the pressure P0 on the hydraulic pressure-supplied circuit 7 side (P0 < P2).
Similarly, the pressure increasing device 30 can open the check valves 36 and 38 and deliver the oil serving as the secondary fluid in the medium-diameter output chamber 30-6 to the hydraulic pressure-supplied circuit 7 side by increasing the pressure P3 in the medium-diameter output chamber 30-6 above the pressure P0 on the hydraulic pressure-supplied circuit 7 side (P0 < P3).
When the pressure P2 and the pressure P3 are set to be the same (P2 = P3) and are reflected in Formula 2, the following Formula 5 is established. In addition, the following Formula 6 is established from Formula 5 and the condition formula for opening the check valve 13 (P0 < P2). $\begin{array}{l} P 1 \times S 1 = P 2 \times S 2 + P 2 \times (S 3 - S 2) \\ P 1 \times S 1 = P 2 \times S 3 \\ ∴ P 2 = P 1 \times S 1 / S 3 \end{array}$ $\begin{array}{l} P 0 < P 2 \\ ∴ P 0 < P 1 \times S 1 / S 3 \end{array}$
From Formula 5, when the electromagnetic switching valve 31 is in the onset position 31-2, the pressure increase ratio of the pressure P2 in the small-diameter output chamber 30-4 and the pressure P3 in the medium-diameter output chamber 30-6 to the pressure P1 in the input chamber 30-3 is S1/S3.
As a result, the pressure increase ratio (S1/S3) when the electromagnetic switching valve 31 is in the onset position 31-2 is smaller than the pressure increase ratio (S1/S2) when the electromagnetic switching valve 31 is in the offset position 31-1.
Namely, by reducing the pressure increase ratio in response to the pressure P1 that is excessive, the pressures P2 and P3 of the pressure-increased oil delivered from the small-diameter output chamber 30-4 and the medium-diameter output chamber 30-6 can be reduced.
In addition, by reducing the pressure increase ratio in response to the pressure P1 that is excessive, the difference between the force F_L1 that moves the piston 30-2 to the left side and the force F_R1 that moves the piston 30-2 to the right side is reduced (F_R1 << F_L1). As a result, the movement speed of the piston 30-2 can be slowed down. This prevents impact from occurring even when the piston 30-2 reaches the terminal end position.
In addition, when the electromagnetic switching valve 31 is in the onset position 31-2, the pressure increasing device 30 delivers the oil not only from the small-diameter output chamber 30-4 but also from the medium-diameter output chamber 30-6, so that the amount of the oil delivered can be increased. As a result, the pressure increasing device 30 can not only supply the oil to the hydraulic pressure-supplied circuit 7 but also efficiently store the oil in the accumulator 6.
When the position sensor (not illustrated) detects that the piston 30-2 has reached the terminal end position, the controller 9 switches the direction switching valve 3 from the right position 3-2 to the left position 3-3. In addition, the electromagnetic switching valve 31 is switched from the onset position 31-2 to the offset position 31-1. The following description is omitted since the following description is the same as when the electromagnetic switching valve 31 is in the offset position 31-1.
As described above, the hydraulic circuit 101 can obtain the desired pressure-increased fluid delivered from the small-diameter output chamber 30-4 or the medium-diameter output chamber 30-6 by changing the pressure increase ratio according to the pressure P1 that is the input pressure. In addition, even when the input pressure fluctuates, the desired pressure-increased fluid can be obtained, and the pressure-increased fluid can be obtained for various pressure values supplied to the pressure increasing device 30, so that a circuit without waste of energy can be achieved.
In addition, the hydraulic circuit 101 can maintain the movement speed of the piston 30-2 of the pressure increasing device 30 substantially constant by changing the pressure increase ratio of the pressure increasing device 30. In this manner, the hydraulic circuit 101 can execute control suitable for the situation.
In addition, the hydraulic circuit 101 can change the pressure increase ratio by selectively switching between increasing the pressure using only the pressure receiving surface 121a or increasing the pressure using both the pressure receiving surfaces 121a and 122a in response to the pressure of the primary fluid. As a result, the hydraulic circuit 101 can improve the responsiveness of control to changes in the situation.
In addition, the hydraulic circuit 101 can change the pressure increase ratio in response to a change in the pressure P1 in the input chamber 30-3 that is detected through the pressure sensor 32. Therefore, the hydraulic circuit 101 can improve the accuracy of control to changes in the situation.
In addition, an output space is provided in the hydraulic circuit 101 for each of the pressure receiving surfaces 121a and 122a. Therefore, the hydraulic circuit 101 can set a plurality of pressure increase ratios with a simple configuration.
In addition, the hydraulic circuit 101 can connect or disconnect the medium-diameter output chamber 30-6, which defines the output space, to or from the hydraulic pressure-supplied circuit 7 side while keeping the small-diameter output chamber 30-4, which defines another output space connected to the hydraulic pressure-supplied circuit 7, connected to the hydraulic pressure-supplied circuit 7 side. As a result, the hydraulic circuit 101 can change the pressure increase ratio while maintaining smooth delivery of the working fluid from the pressure increasing device 30 to the supply destination.
In addition, in the hydraulic circuit 101, the electromagnetic switching valve 31 is provided between the hydraulic pressure-supplied circuit 7 and the medium-diameter output chamber 30-6 constituting one output space. As a result, the hydraulic circuit 101 can set a plurality of pressure increase ratios with a simple configuration in which the electromagnetic switching valve 31 is switched to the offset position 31-1 or the onset position 31-2.
Incidentally, in the above description, a configuration in which the electromagnetic switching valve 31 is in the offset position 31-1 and the electromagnetic switching valve 31 switches to the onset position 31-2 while the piston 30-2 moves to the left side has been described; however, the present invention is not limited thereto, and a configuration in which the electromagnetic switching valve 31 is in the onset position 31-2, and the electromagnetic switching valve 31 switches to the offset position 31-1 while the piston 30-2 moves to the left side may be implemented.
When the controller 9 detects from the pressure signal output from the pressure sensor 32 that the pressure P1 has increased by a predetermined value or more, the controller 9 stops the electrical signal to switch the electromagnetic switching valve 31 to the offset position 31-1. As a result, the pressure increase ratio of the pressure increasing device 30 increases (S1/S3 < S1/S2).
Namely, by increasing the pressure increase ratio in response to the pressure P1 that is insufficient, the pressure P2 of the pressure-increased oil delivered from the small-diameter output chamber 30-4 can be increased.
In addition, by increasing the pressure increase ratio in response to the pressure P1 that is insufficient, the force F_L1 that moves the piston 30-2 to the left side can be made larger than the force F_R1 that moves the piston 30-2 to the right side (F_R1 << F_L1), so that the movement speed of the piston 30-2 is increased.
Even with such control, the hydraulic circuit 101 can obtain the desired pressure-increased fluid delivered from the small-diameter output chamber 30-4 or the medium-diameter output chamber 30-6 by changing the pressure increase ratio of the pressure increasing device 30.
In addition, even with such control, the hydraulic circuit 101 can maintain the movement speed of the piston 30-2 of the pressure increasing device 30 substantially constant by changing the pressure increase ratio of the pressure increasing device 30. In this manner, the hydraulic circuit 101 can execute control suitable for the situation.
With such control, the electromagnetic switching valve may be configured to allow communication between the medium-diameter output chamber 30-6 and the hydraulic pressure-supplied circuit 7 side when in the offset position, and to allow communication between the medium-diameter output chamber 30-6 and the tank 8 when in the onset position. With such a configuration, the amount of electric power consumption can be reduced. In this manner, the configuration of the electromagnetic switching valve may be changed as appropriate.
Incidentally, in the present embodiment, a configuration in which the pressure P1 that is the input pressure changes relative to the pressure P0 on the hydraulic pressure-supplied circuit 7 side has been described; however, the present invention is not limited thereto, and the structure may be such that the pressure of the fluid supplied to the pressure increasing device fluctuates as described above. For example, a configuration in which the input pressure is changed by replacing the hydraulic pump may be implemented, or a configuration in which the working fluid delivered from an actuator such as a hydraulic cylinder flows in may be implemented. Namely, any configuration may be implemented as long as the input pressure changes and the pressure P0 may be constant.
In addition, in the present embodiment, a configuration in which the small-diameter output chamber 30-4 communicates with the ports Pt1 and Ps1 has been described as an example; however, the present invention is not limited thereto, and as long as the pipeline 20 is configured to communicate with the pipeline 18 between the port Ps1 and the check valve 13, the port Pt1 may be omitted. Similarly, as long as the pipeline 18 is configured to communicate with the pipeline 20 between the port Pt1 and the check valve 12, the port Ps1 may be omitted. The same applies to the medium-diameter output chamber 30-6.

{Second embodiment}

Next, a fluid pressure circuit according to a second embodiment of the present invention will be described with reference to FIG. 2. Incidentally, the same reference signs are assigned to the same components as the components illustrated in the first embodiment, and duplicate descriptions will be omitted.
As illustrated in FIG. 2, a hydraulic circuit 201 differs from that in the first embodiment in the structures of a pressure increasing device 50 and an electromagnetic switching valve 51, and pipelines 52, 54, 55, and 57 and check valves 53, 56, and 58 are added.
A casing 50-1 of the pressure increasing device 50 is formed in a stepped cylindrical shape including a large-diameter cylindrical portion 210, a small-diameter cylindrical portion 211, a first medium-diameter cylindrical portion 212, and a second medium-diameter cylindrical portion 213. The large-diameter cylindrical portion 210, the second medium-diameter cylindrical portion 213, the first medium-diameter cylindrical portion 212, and the small-diameter cylindrical portion 211 are disposed in order from right to left. The first medium-diameter cylindrical portion 212 corresponds to the medium-diameter cylindrical portion 112 of the first embodiment.
The second medium-diameter cylindrical portion 213 is provided between the large-diameter cylindrical portion 210 and the first medium-diameter cylindrical portion 212. The second medium-diameter cylindrical portion 213 has a diameter smaller than that of the large-diameter cylindrical portion 210 and larger than that of the first medium-diameter cylindrical portion 212. The other configurations are substantially the same as those of the first medium-diameter cylindrical portion 212.
A piston 50-2 of the pressure increasing device 50 is formed in a stepped columnar shape including a large-diameter columnar portion 220, a small-diameter columnar portion 221, a first medium-diameter columnar portion 222, and a second medium-diameter columnar portion 223. The large-diameter columnar portion 220, the second medium-diameter columnar portion 223, the first medium-diameter columnar portion 222, and the small-diameter columnar portion 221 are disposed in order from right to left. The first medium-diameter columnar portion 222 corresponds to the medium-diameter columnar portion 122 of the first embodiment.
The second medium-diameter columnar portion 223 is provided between the large-diameter columnar portion 220 and the first medium-diameter columnar portion 222. The second medium-diameter columnar portion 223 has a diameter smaller than that of the large-diameter columnar portion 220 and larger than that of the first medium-diameter columnar portion 222. In addition, a cross-sectional area S14 of the second medium-diameter columnar portion 223 is smaller than a cross-sectional area S11 of the large-diameter columnar portion 220, and is larger than a cross-sectional area S12 of the small-diameter columnar portion 221 and a cross-sectional area S13 of the first medium-diameter columnar portion 222 (S12 < S13 < S14 < S11). The other configurations are substantially the same as those of the first medium-diameter columnar portion 222.
By enclosing the piston 50-2 of the casing 50-1, an input chamber 50-3, a small-diameter output chamber 50-4, an oil chamber 50-5, a first medium-diameter output chamber 50-6 defining one output space, and a second medium-diameter output chamber 50-7 defining one output space are formed in the pressure increasing device 50. The first medium-diameter output chamber 50-6 corresponds to the medium-diameter output chamber 30-6 of the first embodiment.
The output chamber of the present invention includes the small-diameter output chamber 50-4, the first medium-diameter output chamber 50-6, and the second medium-diameter output chamber 50-7, and the input chamber of the present invention includes the input chamber 50-3.
The second medium-diameter output chamber 50-7 is formed by an inner surface of the second medium-diameter cylindrical portion 213 of the casing 50-1, a left end surface 223a of the second medium-diameter columnar portion 223 of the piston 50-2, and an outer peripheral surface of the first medium-diameter columnar portion 222. The second medium-diameter output chamber 50-7 communicates with ports Ps3 and Pt3. In addition, when the piston 50-2 is in the starting end position, the second medium-diameter output chamber 50-7 has a longer axial dimension than the first medium-diameter output chamber 50-6.
The left end surface 223a having an annular shape is a pressure receiving surface on which a pressure P14 in the second medium-diameter output chamber 50-7 acts. A pressure receiving area of the left end surface 223a is the same as a difference between the cross-sectional area S14 of the second medium-diameter columnar portion 223 and the cross-sectional area S13 of the first medium-diameter columnar portion 222 (S14 - S13). Hereinafter, the left end surface 223a is referred to as the pressure receiving surface 223a, and the pressure receiving area thereof is referred to as the pressure receiving area (S14 - S13).
The port Ps3 is connected to the pipeline 52. The pipeline 52 is connected to the electromagnetic switching valve 51, and the check valve 53 is provided between the port Ps3 and the electromagnetic switching valve 51. The check valve 53 is configured to allow the oil serving as the secondary fluid to pass therethrough from the port Ps3 to the electromagnetic switching valve 51.
The port Pt3 is connected to the pipeline 55. The pipeline 55 is connected to the pipeline 15, and the check valve 56 is provided between the port Pt3 and the pipeline 15. The check valve 56 is configured to allow the oil serving as the secondary fluid to pass therethrough from the tank 8 side to the port Pt3.
The electromagnetic switching valve 51 is a spring offset type three-position, six-port electromagnetic switching valve. The electromagnetic switching valve 51 in an offset position 51-1 connects the pipeline 35 to the pipeline 39, and connects the pipeline 52 to the pipeline 54. The pipeline 54 is connected to the tank 8.
The electromagnetic switching valve 51 can be switched to a first onset position 51-2 or a second onset position 51-3 in response to an electrical signal input to a solenoid 51a.
The electromagnetic switching valve 51 in the first onset position 51-2 connects the pipeline 35 to the pipeline 37, and connects the pipeline 52 to the pipeline 54.
The electromagnetic switching valve 51 in the second onset position 51-3 connects the pipeline 35 to the pipeline 37, and connects the pipeline 52 to the pipeline 57.
The pipeline 57 is connected to the pipeline 19, and the check valve 58 is provided between the electromagnetic switching valve 51 and the pipeline 19. The check valve 58 is configured to allow the oil serving as the secondary fluid to pass therethrough from the electromagnetic switching valve 51 to the pipeline 19.
Next, a pressure increasing cycle by the hydraulic circuit 201 will be described.
First, a state before the pressure increasing device 50 starts increasing the pressure will be described. In this state, the direction switching valve 3 is in the neutral position 3-1, and the electromagnetic switching valve 51 is in the offset position 51-1.
In the pressure increasing device 50, the oil having substantially the same pressure as the oil in the tank 8 is stored in the input chamber 50-3, the small-diameter output chamber 50-4, the oil chamber 50-5, the first medium-diameter output chamber 50-6, and the second medium-diameter output chamber 50-7.
Next, when the direction switching valve 3 switches to the right position 3-2, the pressure oil delivered from the hydraulic pump 2 flows into the input chamber 50-3.
The piston 50-2 moves to the left side when a force F_L2 that moves the piston 50-2 to the left side is larger than a force F_R2 that moves the piston 50-2 to the right side.
In more detail, the force F_L2 is the product of a pressure P11 in the input chamber 50-3 and the pressure receiving area S11 of a pressure receiving surface 220a (F_L2 = P11 × S11). The force F_R2 is the sum of the product of a pressure P12 in the small-diameter output chamber 50-4 and the pressure receiving area S12 of a pressure receiving surface 221a, the product of the pressure P13 in the first medium-diameter output chamber 50-6 and a pressure receiving area (S13 - S12) of a pressure receiving surface 222a, and the product of the pressure P14 in the second medium-diameter output chamber 50-7 and the pressure receiving area (S14 - S13) of the pressure receiving surface 223a (F_R2 = P12 x S12 + P13 x (S13 - S12) + P14 x (S14 - S13)). As a result, the following Formula 7 is established. P11 × S11 = P12 × S12 + P13 × (S13 - S12) + P14 × (S14 - S13)
The small-diameter output chamber 50-4 communicates with the hydraulic pressure-supplied circuit 7 side via the check valve 13. Meanwhile, when the electromagnetic switching valve 51 is in the offset position 51-1, the first medium-diameter output chamber 50-6 communicates with the tank 8 through both ports Ps2 and Pt2, and the second medium-diameter output chamber 50-7 communicates with the tank 8 through both ports Ps3 and Pt3.
When the pressure in the tank 8 is zero and the pressures P10 to P13 are relative values with respect to the pressure in the tank 8, the following Formula 8 is established from Formula 7. In addition, the following Formula 9 is established from Formula 8 and a condition formula for opening the check valve 13 (P10 < P12). $P 12 = P 11 \times S 11 / S 12$ $\begin{array}{l} P 10 < P 12 \\ ∴ P 10 < P 11 \times S 11 / S 12 \end{array}$
From Formula 8, when the electromagnetic switching valve 51 is in the offset position 51-1, the pressure increase ratio of the pressure P12 in the small-diameter output chamber 50-4 to the pressure P11 in the input chamber 50-3 is S11/S12.
Next, a pressure increasing cycle when the pressure P11 in the input chamber 50-3 becomes excessive with respect to the pressure P10 on the hydraulic pressure-supplied circuit 7 side while the piston 50-2 moves to the left side in a state where the pressure P10 is high will be described.
When the controller 9 detects from the pressure signal output from the pressure sensor 32 that the pressure P11 has decreased by a predetermined value or more, the controller 9 switches the electromagnetic switching valve 51 to the first onset position 51-2.
The pressure increasing device 50 can deliver the oil in the small-diameter output chamber 50-4 and the oil in the first medium-diameter output chamber 50-6 to the hydraulic pressure-supplied circuit 7 side by increasing the pressure P12 in the small-diameter output chamber 50-4 and the pressure P13 in the first medium-diameter output chamber 50-6 above the pressure P10 on the hydraulic pressure-supplied circuit 7 side.
When the pressure P12 and the pressure P13 are set to be the same (P12 = P13) and are reflected in Formula 7, the following Formula 10 is established. In addition, the following Formula 11 is established from Formula 10 and the condition formula for opening the check valve 13 (P10 < P12). $\begin{array}{l} P 11 \times S 11 = P 12 \times S 12 + P 12 \times (S 13 - S 12) \\ P 11 \times S 11 = P 12 \times S 13 \\ ∴ P 12 = P 11 \times S 11 / S 13 \end{array}$ $\begin{array}{l} P 10 < P 12 \\ ∴ P 10 < P 11 \times S 11 / S 13 \end{array}$
From Formula 10, when the electromagnetic switching valve 51 is in the first onset position 51-2, the pressure increase ratio of the pressure P12 in the small-diameter output chamber 50-4 and the pressure P13 in the first medium-diameter output chamber 50-6 to the pressure P11 in the input chamber 50-3 is S11/S13.
As a result, the pressure increase ratio (S11/S13) when the electromagnetic switching valve 51 is in the first onset position 51-2 is smaller than the pressure increase ratio (S11/S12) when the electromagnetic switching valve 51 is in the offset position 51-1.
Namely, by reducing the pressure increase ratio in response to the pressure P11 that is excessive, the pressures P12 and P13 of the pressure-increased oil delivered from the small-diameter output chamber 50-4 and the first medium-diameter output chamber 50-6 can be reduced.
In addition, by reducing the pressure increase ratio in response to the pressure P11 that is excessive, the difference between the force F_L2 that moves the piston 50-2 to the left side and the force F_R2 that moves the piston 50-2 to the right side can be further reduced (F_R2 <<< F_L2), so that the movement speed of the piston 50-2 can be slowed down.
After the electromagnetic switching valve 51 is switched to the first onset position 51-2, when the controller 9 detects from the pressure signal output from the pressure sensor 32 that the pressure P11 has decreased by a predetermined value or more, the controller 9 switches the electromagnetic switching valve 51 to the second onset position 51-3.
The pressure increasing device 50 can deliver the oil in the small-diameter output chamber 50-4, the oil in the first medium-diameter output chamber 50-6, and the oil in the second medium-diameter output chamber 50-7 to the hydraulic pressure-supplied circuit 7 side by increasing the pressure P12 in the small-diameter output chamber 50-4, the pressure P13 in the first medium-diameter output chamber 50-6, and the pressure P14 in the second medium-diameter output chamber 50-7 above the pressure P10 on the hydraulic pressure-supplied circuit 7 side.
When the pressure P12, the pressure P13, and the pressure P14 are set to be the same (P12 = P13 = P14) and are reflected in Formula 7, the following Formula 12 is established. In addition, the following Formula 13 is established from Formula 12 and the condition formula for opening the check valve 13 (P10 < P12). $\begin{array}{l} P 11 \times S 11 = P 12 \times S 12 + P 12 \times (S 13 - S 12) + P 12 \times (\begin{array}{l} S 14 - \\ S 13 \end{array}) \\ P 11 \times S 11 = P 12 \times S 14 \\ ∴ P 12 = P 11 \times S 11 / S 14 \end{array}$ $\begin{array}{l} P 10 < P 12 \\ ∴ P 10 < P 11 \times S 11 / S 14 \end{array}$
From Formula 12, when the electromagnetic switching valve 51 is in the first onset position 51-2, the pressure increase ratio of the pressure P12 in the small-diameter output chamber 50-4 and the pressure P13 in the first medium-diameter output chamber 50-6 to the pressure P11 in the input chamber 50-3 is S11/S14.
As a result, the pressure increase ratio (S11/S14) when the electromagnetic switching valve 51 is in the second onset position 51-3 is smaller than the pressure increase ratio (S11/S13) when the electromagnetic switching valve 51 is in the first onset position 51-2.
Namely, by further decreasing the pressure increase ratio in response to the pressure P11 that is excessive, the pressures P12, P13, and P14 of the pressure-increased oil delivered from the small-diameter output chamber 50-4, the first medium-diameter output chamber 50-6, and the second medium-diameter output chamber 50-7 can be reduced.
In addition, by reducing the pressure increase ratio in response to the pressure P11 that is excessive, the difference between the force F_L2 that moves the piston 50-2 to the left side and the force F_R2 that moves the piston 50-2 to the right side can be further reduced (F_R2 << F_L2), so that the movement speed of the piston 50-2 can be slowed down.
With such a configuration, in the hydraulic circuit 201 of the present embodiment, the number of pressure receiving surfaces disposed in the output chambers can be increased compared to the first embodiment. As a result, the hydraulic circuit 201 of the present embodiment can change the pressure increase ratio of the pressure increasing device 50 more finely to obtain the desired pressure-increased fluid. In addition, even when the input pressure fluctuates, the desired pressure-increased fluid can be obtained, and the pressure-increased fluid can be obtained for various pressure values supplied to the pressure increasing device 50, so that a circuit without waste of energy can be achieved.
In addition, the hydraulic circuit 201 of the present embodiment can change the pressure increase ratio of the pressure increasing device 50 more finely to further reduce a change in the movement speed of the piston 50-2 of the pressure increasing device 50. Therefore, the hydraulic circuit 201 can execute control more suitable for the situation.
In this manner, the number of pressure receiving surfaces disposed in the output chambers may be changed as appropriate.
Incidentally, similarly to the first embodiment, the control of the hydraulic circuit 201 may be changed as appropriate.

{Third embodiment}

Next, a fluid pressure circuit according to a third embodiment of the present invention will be described with reference to FIG. 3. Incidentally, the same reference signs are assigned to the same components as the components illustrated in the second embodiment, and duplicate descriptions will be omitted.
As illustrated in FIG. 3, in a hydraulic circuit 301, a first electromagnetic switching valve 60 and a second electromagnetic switching valve 61 are disposed instead of the electromagnetic switching valve 51 in the second embodiment, and electrical signal lines 62 and 63 are added.
The first electromagnetic switching valve 60 is a spring offset type two-position, three-port electromagnetic switching valve. The first electromagnetic switching valve 60 in an offset position 60-1 connects the pipeline 35 to the pipeline 39.
When an electrical signal is applied to a solenoid 60a of the first electromagnetic switching valve 60 from the controller 9 through the electrical signal line 62, the first electromagnetic switching valve 60 switches to an onset position 60-2. The first electromagnetic switching valve 60 in the onset position 60-2 connects the pipeline 35 to the pipeline 37.
The second electromagnetic switching valve 61 is a spring offset type two-position, three-port electromagnetic switching valve. The second electromagnetic switching valve 61 in an offset position 61-1 connects the pipeline 52 to the pipeline 54.
When an electrical signal is applied to a solenoid 61a of the second electromagnetic switching valve 61 from the controller 9 through the electrical signal line 63, the second electromagnetic switching valve 61 switches to an onset position 61-2. The second electromagnetic switching valve 61 in the onset position 61-2 connects the pipeline 52 to the pipeline 57.
The hydraulic circuit 301 can be set the same as when the electromagnetic switching valve 51 is set to the offset position 51-1 in the second embodiment by setting the first electromagnetic switching valve 60 to the offset position 60-1 and the second electromagnetic switching valve 61 to the offset position 61-1.
In addition, the hydraulic circuit 301 can be set the same as when the electromagnetic switching valve 51 is set to the first onset position 51-2 in the second embodiment by setting the first electromagnetic switching valve 60 to the onset position 60-2 and the second electromagnetic switching valve 61 to the offset position 61-1.
In addition, the hydraulic circuit 301 can be set the same as when the electromagnetic switching valve 51 is set to the second onset position 51-3 in the second embodiment by setting the first electromagnetic switching valve 60 to the onset position 60-2 and the second electromagnetic switching valve 61 to the onset position 61-2.
In this manner, the output switching valve of the present invention may be provided for each output space as in the present embodiment, or one output switching valve may be provided for a plurality of output spaces as in the second embodiment, and the configuration of the output switching valve may be changed as appropriate as long as the output switching valve can switch the output space connected to the supply destination.

{Fourth embodiment}

Next, a fluid pressure circuit according to a fourth embodiment of the present invention will be described with reference to FIG. 4. Incidentally, the same reference signs are assigned to the same components as the components illustrated in the first embodiment, and duplicate descriptions will be omitted.
As illustrated in FIG. 4, a hydraulic circuit 401 is mainly composed of the drive mechanism 1, the hydraulic pump 2, the direction switching valve 3, the relief valve 4, the accumulator 6, the hydraulic pressure-supplied circuit 7 serving as a supply destination, the tank 8, the controller 9, a pressure increasing device 70, an electromagnetic switching valve 71 serving as an input switching valve, the pressure sensor 32, the electrical signal lines 10, 11, 33, and 76, the check valves 12, 13, and 75, and the pipelines 14 to 22 and 72 to 74.
The pipeline 72 is connected to the pipeline 16 between the direction switching valve 3 and the port Ph1. The pipeline 72 is connected to the electromagnetic switching valve 71.
The electromagnetic switching valve 71 is a spring offset type two-position, three-port electromagnetic switching valve. The electromagnetic switching valve 71 in an offset position 71-1 connects the pipeline 72 to the pipeline 73, and prevents the pipeline 73 from communicating with the pipeline 74.
The pipeline 73 is connected to a port Ph2 of the pressure increasing device 70. The pipeline 74 is connected to the tank 8, and the check valve 75 is provided between the electromagnetic switching valve 71 and the tank 8. The check valve 75 is configured to allow the oil serving as the secondary fluid to pass therethrough from the tank 8 side to a port Ph2 side.
When an electrical signal is applied to a solenoid 71a of the electromagnetic switching valve 71 from the controller 9 through the electrical signal line 76, the electromagnetic switching valve 71 switches to an onset position 71-2. The electromagnetic switching valve 71 in the onset position 71-2 connects the pipeline 73 to the pipeline 74, and prevents the pipeline 72 from communicating with the pipeline 73.
A casing 70-1 of the pressure increasing device 70 is formed in a stepped cylindrical shape including a large-diameter cylindrical portion 410, a small-diameter cylindrical portion 411, and a medium-diameter cylindrical portion 412. The medium-diameter cylindrical portion 412, the large-diameter cylindrical portion 410, and the small-diameter cylindrical portion 411 are disposed in order from right side to left.
The large-diameter cylindrical portion 410 is formed in a cylindrical shape with a top which includes a peripheral wall and an annular plate. The port Ph2 penetrating through the peripheral wall of the large-diameter cylindrical portion 410 in the radial direction is provided at a right end of the peripheral wall.
The medium-diameter cylindrical portion 412 is formed in a cylindrical shape with a bottom and a flange which includes a peripheral wall, a circular plate, and an annular plate. The port Ph1 penetrating through the circular plate of the medium-diameter cylindrical portion 412 in the axial direction is provided at the radial center of the circular plate.
A piston 70-2 of the pressure increasing device 70 is formed in a stepped columnar shape including a large-diameter columnar portion 420, a small-diameter columnar portion 421, and a medium-diameter columnar portion 422. The medium-diameter columnar portion 422, the large-diameter columnar portion 420, and the small-diameter columnar portion 421 are disposed in order from right to left.
A cross-sectional area S43 of the medium-diameter columnar portion 422 is smaller than a cross-sectional area S41 of the large-diameter columnar portion 420 and is larger than a cross-sectional area S42 of the small-diameter columnar portion 421 (S42 < S43 < S41).
By enclosing the piston 70-2 in the casing 70-1, a medium-diameter input chamber 70-3 defining one input space, a output chamber 70-4 defining one output space, an oil chamber 70-5, and a large-diameter input chamber 70-8 defining one input space are formed in the pressure increasing device 70. The output chamber of the present invention includes the output chamber 70-4, and the input chamber of the present invention includes the medium-diameter input chamber 70-3 and the large-diameter input chamber 70-8.
In more detail, the medium-diameter input chamber 70-3 is defined by an inner surface of the medium-diameter cylindrical portion 412 of the casing 70-1 and a right end surface 422a of the medium-diameter columnar portion 422 of the piston 70-2. The medium-diameter input chamber 70-3 communicates with the port Ph1.
The right end surface 422a having a circular shape is a pressure receiving surface on which a pressure P41 in the medium-diameter input chamber 70-3 acts. A pressure receiving area of the right end surface 422a is the same as the cross-sectional area S43 of the medium-diameter columnar portion 422. Hereinafter, the right end surface 422a is referred to as the pressure receiving surface 422a, and the pressure receiving area thereof is referred to as the pressure receiving area S43.
The large-diameter input chamber 70-8 is formed by an inner surface of the large-diameter cylindrical portion 410 of the casing 70-1, a right end surface 420a of the large-diameter columnar portion 420 of the piston 70-2, and an outer peripheral surface of the medium-diameter columnar portion 422. The large-diameter input chamber 70-8 communicates with the port Ph2.
The right end surface 420a having an annular shape is a pressure receiving surface on which a pressure P44 in the large-diameter input chamber 70-8 acts. A pressure receiving area of the right end surface 420a is the same as a difference between the cross-sectional area S41 of the large-diameter columnar portion 420 and the cross-sectional area S43 of the medium-diameter columnar portion 422 (S41 - S43). Hereinafter, the right end surface 420a is referred to as the pressure receiving surface 420a, and the pressure receiving area thereof is referred to as the pressure receiving area (S41 - S43).
Next, a pressure increasing cycle by the hydraulic circuit 401 will be described.
First, a state before the pressure increasing device 70 starts increasing the pressure will be described. In this state, the direction switching valve 3 is in the neutral position 3-1, and the electromagnetic switching valve 71 is in the offset position 71-1.
In the pressure increasing device 70, the oil having substantially the same pressure as the oil in the tank 8 is stored in the medium-diameter input chamber 70-3, the output chamber 70-4, the oil chamber 70-5, and the large-diameter input chamber 70-8.
Next, when the direction switching valve 3 switches to the right position 3-2, the pressure oil delivered from the hydraulic pump 2 flows into the medium-diameter input chamber 70-3 and the large-diameter input chamber 70-8.
The piston 70-2 moves to the left side when a force F_L4 that moves the piston 70-2 to the left side is larger than a force F_R4 that moves the piston 70-2 to the right side.
In more detail, the force F_L4 is the sum of the product of the pressure P41 in the medium-diameter input chamber 70-3 and the pressure receiving area S43 of the pressure receiving surface 422a and the product of the pressure P44 in the large-diameter input chamber 70-8 and the pressure receiving area (S41 - S43) of the pressure receiving surface 420a (F_L4 = P41 x S43 + P44 x (S41 - S43)). The force F_R4 is the product of a pressure P42 in the output chamber 70-4 and the pressure receiving area S42 of a pressure receiving surface 421a (F_R4 = P42 × S42). As a result, the following Formula 14 is established. $P 41 \times S 43 + P 44 \times (S 41 - S 43) = P 42 \times S 42$
The medium-diameter input chamber 70-3 and the large-diameter input chamber 70-8 are connected in parallel to the hydraulic pump 2. As a result, when the pressure P41 and the pressure P44 are set to be the same (P41 = P44) and are reflected in Formula 14, the following Formula 15 is established. In addition, the following Formula 16 is established from Formula 15 and a condition formula for opening the check valve 13 (P40 < P42). $\begin{array}{l} P 41 \times S 43 + P 41 \times (S 41 - S 43) = P 42 \times S 42 \\ P 41 \times S 41 = P 42 \times S 42 \\ ∴ P 42 = P 41 \times S 41 / S 42 \end{array}$ $\begin{array}{l} P 40 < P 42 \\ ∴ P 40 < P 41 \times S 41 / S 42 \end{array}$
From Formula 15, when the electromagnetic switching valve 71 is in the offset position 71-1, the pressure increase ratio of the pressure P42 in the output chamber 70-4 to the pressure P41 in the medium-diameter input chamber 70-3 and the pressure P44 in the large-diameter input chamber 70-8 is S41/S42.
Next, a pressure increasing cycle when the pressure P41 in the medium-diameter input chamber 70-3 and the pressure P44 in the large-diameter input chamber 70-8 becomes excessive with respect to a pressure P40 on the hydraulic pressure-supplied circuit 7 side while the piston 70-2 moves to the left side in a state where the pressure P40 is high will be described.
When the controller 9 detects from the pressure signal output from the pressure sensor 32 that the pressures P41 and P44 have decreased by a predetermined value or more, the controller 9 switches the electromagnetic switching valve 71 to the onset position 71-2.
When the piston 70-2 moves to the left side, the pressure in the large-diameter input chamber 70-8 becomes relatively negative, and the oil in the tank 8, which serves as the secondary fluid, is suctioned into the large-diameter input chamber 70-8 through the pipelines 73 and 74. As a result, the oil in the tank 8 is supplied into the large-diameter input chamber 70-8, and the pressure P44 in the large-diameter input chamber 70-8 becomes substantially the same as the pressure in the tank 8.
When the pressure in the tank 8 is zero and the pressures P40 to P42 and P44 are relative values with respect to the pressure in the tank 8, the following Formula 17 is established from Formula 14. In addition, the following Formula 18 is established from Formula 17 and the condition formula for opening the check valve 13 (P40 < P42). $\begin{array}{l} P 41 \times S 43 = P 42 \times S 42 \\ ∴ P 42 = P 41 \times S 43 / S 42 \end{array}$ $\begin{array}{l} P 40 < P 42 \\ ∴ P 40 < P 41 \times S 43 / S 42 \end{array}$
From Formula 17, when the electromagnetic switching valve 71 is in the onset position 71-2, the pressure increase ratio of the pressure P42 in the output chamber 70-4 to the pressure P41 in the medium-diameter input chamber 70-3 is S43/S42.
As a result, the pressure increase ratio (S43/S42) when the electromagnetic switching valve 71 is in the onset position 71-2 is smaller than the pressure increase ratio (S41/S42) when the electromagnetic switching valve 71 is in the offset position 71-1.
Namely, by reducing the pressure increase ratio in response to the pressures P41 and P44 that are excessive, the pressure P42 of the pressure-increased oil delivered from the output chamber 70-4 can be reduced.
In addition, by reducing the pressure increase ratio in response to the pressures P41 and P44 that are excessive, the difference between the force F_L4 that moves the piston 70-2 to the left side and the force F_R4 that moves the piston 70-2 to the right side can be reduced (F_R4 << F_L4), so that the movement speed of the piston 70-2 can be slowed down.
When a position sensor (not illustrated) detects that the piston 70-2 has reached the terminal end position, the controller 9 switches the direction switching valve 3 from the right position 3-2 to the left position 3-3. In addition, the electromagnetic switching valve 71 is switched from the onset position 71-2 to the offset position 71-1.
As a result, the oil in the medium-diameter input chamber 70-3 and the oil in the large-diameter input chamber 70-8 can be discharged into the tank 8 through the pipelines 16 and 15 or the pipelines 73, 16, and 15.
In this manner, even in the hydraulic circuit 401 in which two pressure receiving surfaces 420a and 422a are provided in the input chamber, the movement speed of the piston 70-2 of the pressure increasing device 70 can be maintained substantially constant by changing the pressure increase ratio of the pressure increasing device 70. Therefore, the hydraulic circuit 401 can execute control suitable for the situation.
In addition, in the hydraulic circuit 401, the input space is provided for each of the pressure receiving surfaces 420a and 422a. Therefore, the hydraulic circuit 401 can set a plurality of pressure increase ratios with a simple configuration.
In addition, the hydraulic circuit 401 can connect or disconnect the large-diameter input chamber 70-8, which constitutes the input space, to or from the hydraulic pump 2 while keeping the medium-diameter input chamber 70-3, which constitutes another input space connected to the hydraulic pump 2, connected to the hydraulic pump 2. As a result, the hydraulic circuit 401 can change the pressure increase ratio while maintaining smooth delivery of the working fluid from the pressure increasing device 70 to the supply destination.
In addition, in the hydraulic circuit 401, the electromagnetic switching valve 71 is provided between the hydraulic pressure-supplied circuit 7 and the large-diameter input chamber 70-8. As a result, the hydraulic circuit 401 can set a plurality of pressure increase ratios with a simple configuration in which the electromagnetic switching valve 71 is switched to the offset position 71-1 or the onset position 71-2.
Incidentally, in the present embodiment, a configuration in which two pressure receiving surfaces are provided in the input chamber has been described; however, the present invention is not limited thereto, and three or more pressure receiving surfaces may be provided. Furthermore, similarly to the first to third embodiments, two or more pressure receiving surfaces may be provided in the output chamber.
In addition, similarly to the first embodiment, the control of the hydraulic circuit 401 may be changed as appropriate.
The embodiments of the present invention have been described above with reference to the drawings; however, specific configurations are not limited to these embodiments, and modifications or additions that are made without departing from the scope of the present invention are also included in the present invention.
For example, in the first to fourth embodiments, the fluid pressure circuit has been described as being a hydraulic circuit in which oil is pumped; however, the present invention is not limited thereto. The working fluid may be a fluid other oil, and the fluid to be applied may be changed as appropriate.
In addition, in the first to fourth embodiments, the actuator disposed at the supply destination has been described as being a hydraulic cylinder; however, the present invention is not limited thereto. The actuator may be a hydraulic motor and may be changed as appropriate.
In addition, in the first to fourth embodiments, a configuration in which the pressure oil serving as the primary fluid delivered from the hydraulic pump is supplied only to the input chamber and the oil chamber of the pressure increasing device has been described; however, the present invention is not limited thereto, and a configuration in which the pressure oil is also supplied to the hydraulic pressure-supplied circuit may be implemented.
In addition, in the first to fourth embodiments, a configuration in which the accumulator is applied has been described; however, the present invention is not limited thereto. The accumulator may not be applied or a generator may be applied instead of the accumulator, and changes may be made as appropriate.
In addition, in the first to fourth embodiments, the casing has been described as having a stepped cylindrical shape formed by connecting cylinders having different radial dimensions; however, the present invention is not limited thereto, and the casing may have any shape as long as the area ratio can be changed.
In addition, in the first to fourth embodiments, the piston has been described as having a stepped columnar shape formed by connecting columns having different radial dimensions; however, the present invention is not limited thereto, and the piston may have a configuration in which a plurality of disks are spaced apart from each other in the axial direction and are fixed to a rod, an end surface on one axial side of each disk functions as a pressure receiving surface on the input chamber side, and an end surface on the other axial side functions as a pressure receiving surface on the output chamber side.
In more detail, the shapes of the casing and the piston may be changed as appropriate as long as the casing and the piston have a configuration in which the sum of the pressure receiving areas disposed in the output chamber is smaller than the sum of the pressure receiving areas disposed in the input chamber.
In addition, in the first to fourth embodiments, the pressure increasing device has been described as being of a so-called single-acting type that increases pressure only when the piston moves to one side in the axial direction; however, the present invention is not limited thereto, and the pressure increasing device may be of a double-acting type that increases pressure both when the piston moves to the one side in the axial direction and when the piston moves to the other side in the axial direction.

{REFERENCE SIGNS LIST}

101 Hydraulic circuit
1 Drive mechanism
2 Hydraulic pump (fluid supply device)
3 Electromagnetic direction switching valve
6 Accumulator
7 Hydraulic pressure-supplied circuit (supply destination)
8 Tank
30 Pressure increasing device
30-1 Casing
30-2 Piston
30-3 Input chamber (input space)
30-4 Small-diameter output chamber (output space)
30-6 Medium-diameter output chamber (output space)
31 Electromagnetic switching valve (output switching valve)
32 Pressure sensor
120a Pressure receiving surface (pressure receiving surface of input chamber)
121a, 122a Pressure receiving surface (pressure receiving surface of output chamber)
201 Hydraulic circuit
50 Pressure increasing device
50-1 Casing
50-2 Piston
50-3 Input chamber (input space)
50-4 Small-diameter output chamber (output space)
50-6 First medium-diameter output chamber (output space)
50-7 Second medium-diameter output chamber (output space)
51 Electromagnetic switching valve (output switching valve)
220a Pressure receiving surface (pressure receiving surface of input chamber)
221a, 222a, 223a Pressure receiving surface (pressure receiving surface of output chamber)
301 Hydraulic circuit
60 First electromagnetic switching valve (output switching valve)
61 Second electromagnetic switching valve (output switching valve)
401 Hydraulic circuit
70 Pressure increasing device
70-1 Casing
70-2 Piston
70-3 Medium-diameter input chamber (input space)
70-4 Output chamber (output space)
70-8 Large-diameter input chamber (input space)
71 Electromagnetic switching valve (input switching valve)
420a, 422a Pressure receiving surface (pressure receiving surface of input chamber)
421a Pressure receiving surface (pressure receiving surface of output chamber)

Claims

A fluid pressure circuit, comprising:
a fluid supply device that delivers a primary fluid; and

a pressure increasing device configured for increasing a pressure of a secondary fluid in an output chamber using the primary fluid input from the fluid supply device to an input chamber, and delivering the secondary fluid to a supply destination,

wherein the pressure increasing device is configured such that at least one of the input chamber and the output chamber includes a plurality of pressure receiving surfaces and a pressure increase ratio of the secondary fluid to the primary fluid is changeable.
The fluid pressure circuit according to claim 1,
wherein the fluid pressure circuit is configured to change the pressure increase ratio by selectively switching between the plurality of pressure receiving surfaces.
The fluid pressure circuit according to claim 1, further comprising:
a pressure sensor that detects a pressure of the primary fluid.
The fluid pressure circuit according to claim 1,
wherein the output chamber has output spaces, each of the spaces being for each of the pressure receiving surfaces.
The fluid pressure circuit according to claim 4,
wherein the fluid pressure circuit is configured to change the pressure increase ratio by increasing or decreasing the number of the output spaces connected to the supply destination.
The fluid pressure circuit according to claim 4 or 5, further comprising:
an output switching valve disposed between the supply destination and at least one of the output spaces.
The fluid pressure circuit according to claim 1,
wherein the input chamber has input spaces, each of the input spaces being for each of the pressure receiving surfaces.
The fluid pressure circuit according to claim 7,
wherein the fluid pressure circuit is configured to change the pressure increase ratio by increasing or decreasing the number of the input spaces connected to the fluid supply device.
The fluid pressure circuit according to claim 7 or 8, further comprising:
an input switching valve disposed between the fluid supply device and at least one of the input spaces.