Hydraulic system

Abstract

To provide a hydraulic unit capable of suppressing energy loss caused by heat of a pressure reduction valve, and capable of achieving improvement of energy efficiency and reduction of the cost.SOLUTION: A hydraulic system of the present invention includes a hydraulic pump 110, a changeover valve 130 for supplying a hydraulic pressure to actuators (first actuator 190b, second actuator 190c), a first pressure sensor 120 for detecting a primary side pressure of the changeover valve 130, and second pressure sensors 150a, 150b for detecting a secondary side pressure of the changeover valve 130. The hydraulic pump 110 operates so as to maintain the primary side pressure on the basis of the pressure detected by the first pressure sensor 120, and the changeover valve 130 performs ON / OFF control to maintain the secondary side pressure lower than the primary side pressure on the basis of the pressure detected by the second pressure sensors 150a, 150b.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hydraulic system that supplies hydraulic oil discharged from a hydraulic pump to an actuator. [Background technology]

[0002] Conventionally, hydraulic systems that supply hydraulic oil discharged from a hydraulic pump to an actuator are known, particularly hydraulic systems that use an accumulator and a pressure reducing valve to stabilize the hydraulic pressure even when the hydraulic cylinder of the actuator is operating and reduce the capacity of the hydraulic pump.

[0003] For example, Patent Document 1 discloses a hydraulic unit comprising: "a hydraulic pump connected to a primary side line; an accumulator connected to the primary side line and storing hydraulic oil discharged from the hydraulic pump; the primary side line for introducing hydraulic oil from the accumulator and a secondary side line for discharging the introduced hydraulic oil toward an actuator; and a non-leak pressure reducing valve for adjusting the pressure of the hydraulic oil in the secondary side line to a pressure lower than that of the primary side line, the secondary side line being connected to the primary side line only via the non-leak pressure reducing valve, and the hydraulic pump being connected to the actuator only via the secondary side line." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5782483 Summary of the Invention [Problem to be solved by the invention]

[0005] In the hydraulic unit of Patent Document 1, the primary line and the secondary line are connected only by a non-leak pressure reducing valve, and hydraulic oil whose pressure is adjusted to a lower pressure than the pressure in the primary line by the non-leak pressure reducing valve (hereinafter simply referred to as the pressure reducing valve) is fed to the secondary line. However, the pressure reducing valve is a component that easily generates heat, and thus causes a large energy loss. For this reason, further improvements are required to improve the energy efficiency of the hydraulic unit.

[0006] In view of the above problems, the present invention aims to provide a hydraulic unit that can suppress energy loss caused by heat generation in a pressure reducing valve, thereby improving energy efficiency and reducing costs. [Means for solving the problem]

[0007] In view of the above problems, a representative configuration of a hydraulic system according to the present invention includes a hydraulic pump, a switching valve that supplies hydraulic pressure to an actuator, a first pressure sensor that detects the pressure on the primary side of the switching valve, and a second pressure sensor that detects the pressure on the secondary side of the switching valve, wherein the hydraulic pump operates to maintain the primary side pressure based on the pressure detected by the first pressure sensor, and the switching valve performs ON / OFF control to maintain the secondary side pressure that is lower than the primary side pressure based on the pressure detected by the second pressure sensor. Effect of the Invention

[0008] According to the present invention, it is possible to provide a hydraulic unit that can suppress energy loss caused by heat generation in the pressure reducing valve, thereby achieving energy efficiency and cost reduction. [Brief description of the drawings]

[0009] [Figure 1] 1 is a hydraulic circuit diagram illustrating a hydraulic system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific values ​​shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present invention are not shown.

[0011] Fig. 1 is a hydraulic circuit diagram illustrating a hydraulic system 100 according to this embodiment. As shown in Fig. 1, the hydraulic system 100 of this embodiment is composed of a pump system 100a, a first pressure reduction system 100b, and a second pressure reduction system 100c.

[0012] The pump system 100a, the first pressure reduction system 100b, and the second pressure reduction system 100c are connected by a pump line 102 and a drain line 104. A relief valve 106 that returns excess pressure in the pump line 102 to the drain 114 is provided between the pump line 102 and the drain line 104. The pump line 102 is, in other words, a pipe on the primary side (hydraulic pump 110 side) of a switching valve 130 provided in the first pressure reduction system 100b and the second pressure reduction system 100c.

[0013] The pump system 100a includes a hydraulic pump 110 and a first pressure sensor 120. The hydraulic pump 110 operates using a motor 112 as a drive source, and pressurizes the hydraulic oil in a drain 114 and sends it to the pump line 102. A filter 116 is provided upstream of the hydraulic pump 110, and a check valve 118 is provided downstream of the hydraulic pump 110 to prevent backflow of the hydraulic oil to the hydraulic pump 110.

[0014] The first pressure sensor 120 (PS1) is connected to the pump line 102 and detects the pressure of the pump line 102. The first pressure sensor 120 and the motor 112 are connected to a primary pressure maintenance control unit 122. The primary pressure maintenance control unit 122 controls the motor 112 based on the pressure of the pump line 102 detected by the first pressure sensor 120.

[0015] The first pressure reduction system 100b and the second pressure reduction system 100c are connected to the first actuator 190b and the second actuator 190c, respectively, and reduce the pressure of the hydraulic oil sent from the hydraulic pump 110 through the pump line 102 from high pressure to low pressure. Note that the first pressure reduction system 100b and the second pressure reduction system 100c have the same configuration although different actuators are connected, so the first pressure reduction system 100b will be described below as an example, and the second pressure reduction system 100c will be given the same reference numerals and description thereof will be omitted.

[0016] The first pressure reducing system 100b includes a switching valve 130 and second pressure sensors 150a, 150b (two PS2). The switching valve 130 supplies hydraulic oil to the first actuator 190b (the switching valve 130 of the second pressure reducing system 100c supplies hydraulic oil to the second actuator 190c). In this embodiment, a four-port, three-position directional control valve is illustrated as the switching valve 130. However, this is not limited thereto, and the type of the switching valve 130 can be appropriately selected. For example, if the cylinder 192 of the first actuator 190b or the second actuator 190c has a return spring, a three-port, two-position directional control valve may be used as the switching valve 130.

[0017] As described above, the pump line 102 is connected to the P port on the primary side of the switching valve 130. The first actuator 190b is connected to the A and B ports on the secondary side of the switching valve 130 via pressure supply lines 140a and 140b. When the A port is opened, hydraulic oil is supplied from the pressure supply line 140a to the first actuator 190b, and the piston 194 moves upward in the cylinder 192 in the figure. When the B port is opened, hydraulic oil is supplied from the pressure supply line 140b to the first actuator 190b, and the piston 194 moves downward in the cylinder 192 in the figure.

[0018] A pilot check valve 142 and a throttle 144 are disposed in each of the supply pressure lines 140a and 140b. Second pressure sensors 150a and 150b are also provided in each of the supply pressure lines 140a and 140b. The second pressure sensors 150a and 150b detect the pressure in the supply pressure lines 140a and 140b, which are on the secondary side (actuator side) of the switching valve 130.

[0019] The second pressure sensors 150a, 150b and the switching valve 130 are connected to a secondary pressure generating circuit 152. The secondary pressure generating circuit 152 controls the switching valve 130 based on the pressures in the supply pressure lines 140a and 140b detected by the second pressure sensors 150a, 150b.

[0020] As a feature of the hydraulic system 100 of this embodiment, the primary pressure maintenance control unit 122 controls the hydraulic pump 110 based on the pressure detected by the first pressure sensor 120, and operates the hydraulic pump 110 to maintain a high primary side pressure. As an example, the primary pressure maintenance control unit 122 turns the motor 112 ON when the primary side pressure falls below 6.5 MPa, and turns the motor 112 OFF when the primary side pressure exceeds 7.0 MPa.

[0021] Further, the secondary pressure generating circuit 152 performs ON / OFF control of the switching valve 130 so as to maintain the secondary side pressure lower than the primary side pressure based on the pressure detected by the second pressure sensors 150a, 150b. As an example, the secondary pressure generating circuit 152 turns on the switching valve 130 when the secondary side pressure falls below 6.0 MPa, and turns off the switching valve 130 when the secondary side pressure reaches 6.0 MPa.

[0022] According to the above configuration, the pressure of the hydraulic oil sent from the hydraulic pump 110 can be reduced to a low pressure, i.e., the input pressure (secondary pressure) of the actuator, in the switching valve 130, eliminating the need for a pressure reducing valve. Therefore, energy loss caused by heat generation in the pressure reducing valve can be suppressed, and it is possible to improve energy efficiency and reduce device costs.

[0023] In addition, in the above configuration, the primary pressure maintenance control unit 122 controls the hydraulic pump 110 to maintain the primary pressure. Therefore, an accumulator that was used to maintain the primary pressure in conventional hydraulic systems is no longer necessary. This makes it possible to further reduce the cost of the device and contribute to reducing the facility space.

[0024] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an example. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. [Industrial Applicability]

[0025] INDUSTRIAL APPLICABILITY The present invention can be used as a hydraulic system that supplies hydraulic oil discharged from a hydraulic pump to an actuator. [Explanation of symbols]

[0026] 100...hydraulic system, 100a...pump system, 100b...first pressure reduction system, 100c...second pressure reduction system, 102...pump line, 104...drain line, 106...relief valve, 110...hydraulic pump, 112...motor, 114...drain, 116...filter, 118...check valve, 120...first pressure sensor, 122...primary pressure maintenance control unit, 130...switching valve, 140a...supply pressure line, 140b...supply pressure line, 142...pilot check valve, 144...restriction, 150a...second pressure sensor, 150b...second pressure sensor, 152...secondary pressure generating circuit, 190b...first actuator, 190c...second actuator, 192...cylinder, 194...piston

Claims

[Claim 1] A hydraulic pump; A switching valve that supplies hydraulic oil to the actuator; A first pressure sensor that detects a pressure on a primary side of the switching valve; A second pressure sensor that detects a pressure on the secondary side of the switching valve; Equipped with The hydraulic pump operates to maintain a primary side pressure based on the pressure detected by the first pressure sensor; A hydraulic system characterized in that the switching valve performs ON / OFF control so as to maintain a secondary side pressure that is lower than the primary side pressure, based on the pressure detected by the second pressure sensor.

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