JPH0610838U - Oil pressure detector - Google Patents

Abstract

(57) [Summary] [Purpose] It is not affected by the surge pressure generated in the pressure oil, and only when the pressure of the pressure oil constantly reaches the predetermined pressure.
Provided is a hydraulic pressure detection device capable of detecting that the hydraulic pressure has risen. [Structure] The hydraulic pressure detection device 30 is a hydraulic actuator 1.
6 has a pressure switch 31 which guides a part of the pressure oil supplied to the pressure sensor 6 and receives and operates a pressure of the pressure oil that has reached a predetermined pressure. Further, there is provided a throttle portion 34 branched from an introduction oil passage 35 for guiding pressure oil to the pressure switch 31 and connected to the oil tank T, and having a passage area smaller than the minimum passage area of the introduction oil passage 35. A surge pressure releasing oil passage 33 is also provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic pressure detection device for detecting whether or not the pressure of pressure oil supplied to a hydraulic actuator such as a hydraulic cylinder has reached a predetermined pressure.

[0002]

[Prior art]

 The hydraulic actuator may be automatically controlled according to the pressure of the pressure oil supplied to the hydraulic actuator. For example, mobile cranes and aerial work vehicles are equipped with outrigger jacks at four locations on the front, rear, left, and right of the vehicle body.After these outrigger jacks are extended to the side of the vehicle body, the lower-end grounding plate is grounded. It is designed to ensure stability. Since the burden on the operator is heavy if the projecting operation is performed for each jack, the projecting of these four outrigger jacks can be automatically carried out by operating only one start switch on a work vehicle such as an aerial work platform. It is often equipped with an automatic overhang device.

In this automatic overhang device, an operator operates a start switch to supply pressure oil to an overhanging hydraulic cylinder that drives the outrigger jacks to overhang, and extends the hydraulic cylinder to the stroke end. Make the outrigger jack extend to the maximum. If pressure oil continues to be supplied to this overhang hydraulic cylinder even after the stroke end, the pressure oil is supplied before the overhang hydraulic cylinder reaches the stroke end (during stroke). It rises above the hydraulic pressure. For this reason, the controller of the automatic overhang device recognizes that the outrigger jack is overhanging by detecting that the pressure oil is in such a high pressure state, and the pressure for each overhang hydraulic cylinder is detected. The oil supply can be stopped.

A pressure switch is used to detect that the pressure oil is in a high pressure state. This pressure switch guides a part of the pressure oil supplied to the overhanging hydraulic cylinder, and is directly detected by the pressure of the pressure oil reaching a predetermined high pressure, and sends a detection signal to the controller.

[0005]

[Problems to be solved by the device]

 However, for example, when the outrigger jack extension operation starts, a load due to static friction between the members forming the outrigger jack extension mechanism acts on the extension hydraulic cylinder, and the extension hydraulic cylinder is supplied to the extension hydraulic cylinder. The pressure oil may momentarily become high in pressure. In addition, surge pressure may be generated for some reason even while the outrigger jack is being extended. If the surge pressure thus generated acts on the pressure switch and is detected and operated, the overhang operation of the outrigger jack will stop before the overhang operation is completed. is there.

The present invention has been made in view of such a problem, and is not affected by the surge pressure generated in the pressure oil, and only when the pressure of the pressure oil constantly reaches a predetermined pressure. It is an object of the present invention to provide an oil pressure detection device capable of detecting this.

[0007]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the oil pressure detecting device of the present invention is a pressure switch that guides a part of the pressure oil supplied to the hydraulic actuator and receives the pressure of the pressure oil that has reached a predetermined pressure for detection operation. In addition to this, the surge pressure release is provided by branching from the introduction oil passage that guides pressure oil to this pressure switch and connecting to the oil tank, and by providing a throttle with a passage area smaller than the minimum passage area of the introduction oil passage It has an oil passage.

[0008]

[Action]

 According to such a hydraulic pressure detecting device, for example, the surge pressure generated during the stroke of the hydraulic actuator is released to the oil tank through the surge pressure releasing oil passage. Therefore, it is possible to prevent the surge pressure from directly acting on the pressure switch. On the other hand, the pressure of the pressure oil that rises after the hydraulic actuator reaches the stroke end acts on the pressure switch with almost no decrease due to the presence of the throttle portion in the surge pressure release oil passage. For this reason, the pressure switch is operated to detect that the hydraulic pressure has reached a predetermined pressure (the hydraulic actuator has reached the stroke end).

[0009]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows an aerial work vehicle 10 equipped with a hydraulic pressure detection device according to the present invention. A table 12 is attached. A boom 13 is telescopically attached to the upper part of the swivel base 12 so as to be telescopic. Further, a workbench 14 is horizontally attached to the tip of the boom 13. An operator can board the work table 14, and the worker can move to an arbitrary height by controlling the operation of the boom 13 and the like.

By operating the boom 13 or the like, a load acts on the vehicle body 11 in a direction to tip it over. Therefore, the outrigger jacks 15 are provided at four positions on the front, rear, left and right sides of the vehicle body 11. There is. The outrigger jack 15 is constructed by attaching a jack 15b to the tip of a beam member 15a which is capable of expanding and contracting laterally of the vehicle body 11. The expansion / contraction operation of the beam member 15a is driven by the expansion / contraction operation of a hydraulic extension cylinder (hereinafter, simply referred to as an extension cylinder) 16 incorporated in the beam member 15a. The jack 15b is configured to be capable of expanding and contracting downward, and supports the vehicle body 11 with respect to the ground by grounding a ground plate 15c attached to the lower end. The expansion / contraction operation of the jack 15b is driven by the expansion / contraction operation of a hydraulic jack cylinder (hereinafter, simply referred to as a jack cylinder) 17 built in the jack 15b.

In order to support the vehicle body 11 by the outrigger jack 15 configured as described above, first, the beam member 15 a is extended and the jack 15 b is extended to the side of the vehicle body 11. Then, the jack 15b is extended to ground the ground plate 15c to complete the support. In this way, by grounding the jack 15b in a state where the jack 15b is extended to the side of the vehicle body 11, it is possible to improve the stability of the vehicle body 11 and move the workbench 14 in a wide range. On the other hand, the jack 15b can be stored in the vehicle body 11 by reducing the jack 15b to raise the ground plate 15c, and then reducing the beam member 15a to bring the jack 15b close to the vehicle body 11.

By the way, the aerial work vehicle 10 is equipped with an automatic overhang device for automatically overhanging and retracting the jack 15b only by a first activation instruction operation by an operator. The automatic overhang device will be described below with reference to FIG. The automatic overhang device 20 includes an overhang side hydraulic circuit 21, a ground side hydraulic circuit 22, an overhang / grounding switching circuit 23, and a controller 24. The overhanging side hydraulic circuit 21 has an overhanging valve unit 21b that receives the supply of the hydraulic oil discharged from the hydraulic pump P via the overhanging oil passage 21a and distributes and supplies it to each overhanging cylinder 16. The grounding side hydraulic circuit 22 has a grounding valve unit 22b which receives the supply of the hydraulic oil discharged from the hydraulic pump P through the grounding oil passage 22a and supplies the hydraulic oil to each jack cylinder 17 in a distributed manner. .

The overhang / grounding switching circuit 23 includes a switching valve 23a for selectively connecting the discharge oil passage 25 connected to the discharge port of the hydraulic pump P to one of the overhanging oil passage 21a and the grounding oil passage 22a. , And an oil pressure detecting device 30 according to the present invention. The switching valve 23a is a three-position switching type electromagnetic switching control valve, and has a neutral position where the discharge oil passage 25 is drained to the oil tank T, and a left moving position where the discharge oil passage 25 is connected to the overhanging oil passage 21a. And a right moving position connected to the grounding oil passage 22a.

The hydraulic pressure detection device 30 has a pressure switch 31, a main throttle 32, and a surge pressure releasing oil passage 33. The pressure switch 31 guides a part of the pressure oil supplied to each of the overhanging cylinders 16 via an introduction oil passage 35 branched from the overhanging oil passage 21a. When the pressure of the pressure oil in the introduction oil passage 35 reaches a predetermined high pressure, the pressure is directly detected and operated. A detection signal (electrical signal) is output from the pressure switch 31 that has been operated for detection.

The above “predetermined high pressure” means that the pressure oil continues to be supplied even though each of the overhanging cylinders 16 has been operated to the stroke end, so that the overhanging oil passage 21 a and the introduction oil passage 35. Among the pressures generated when the pressure of the pressure oil in the inside rises, those pressures are selected and set in advance. Therefore, the pressure is higher than that when each overhanging cylinder 16 is operating in the middle of the stroke.

The main throttle 32 is attached to the introduction oil passage 35, and narrows the flow passage area of the introduction oil passage 35 to such an extent that the flow rate of the pressure oil required for the detection operation of the pressure switch 31 can pass. The surge pressure release oil passage 33 branches from the downstream side of the installation position of the main throttle 32 in the introduction oil passage 35 and is connected to the oil tank T. The surge pressure releasing oil passage 33 is provided with an open throttle (“throttle portion” in the claims) 34 for narrowing the flow passage area of the surge pressure releasing oil passage 33 at the intermediate portion thereof. The flow passage area of the portion throttled by the open throttle 34 is considerably smaller than the minimum flow passage area of the introduction oil passage 35 throttled by the main throttle 32. Therefore, the flow rate of the pressure oil passing through the open throttle 34, together with the flow rate limitation by the main throttle 32, is limited to an extremely small amount as compared with the flow rate in the oil passage 21a for overhanging.

The controller 24 is connected to a start switch 27 that is operated to instruct the start of the automatic overhang device 20, and the controller 24 outputs the start signal output from the start switch 27 and the pressure switch 31. Switching control of the overhang valve unit 21b and the switching valve 23a is performed based on the output detection signal. Hereinafter, the control content will be described together with the operation of the oil pressure detection device 30. However, the automatic extension operation of the jack 15b will be described here.

The controller 24 receiving the start signal from the start switch 27 switches the switching valve 23a from the neutral position to the left position and sends a control signal to the overhang valve unit 21b so that the overhang valve unit 21b receives the control signal. The supply of pressure oil to each overhang cylinder 16 is started. As a result, the extension operation of each extension cylinder 16, that is, the extension operation of each jack 15b is started.

Here, from the start of the supply of the pressure oil to each overhanging cylinder 16 to the actual movement of each jack 15 b, the static pressure generated on the contact surface between the beam member 15 a and the vehicle body 11 or the like. A load due to friction acts on each overhanging cylinder 16. Therefore, the pressure of the pressure oil supplied to each overhanging cylinder 16 may momentarily increase. The surge pressure thus generated also affects the pressure of the pressure oil in the introduction oil passage 35. However, since the surge pressure relief oil passage 33 is provided in the introduction oil passage 35, most of the surge pressure is released from the surge pressure relief oil passage 33 to the tank T, and the surge oil of the pressure oil in the introduction oil passage 35 is released. The pressure hardly rises. Therefore, the pressure switch 31 is not detected and operated by such surge pressure.

When each overhanging cylinder 16 extends to the stroke end and each jack 15b overhangs to the maximum width, the pressure of the pressure oil in the overhanging oil passage 21a rises as described above. The pressure rise is continuous or steady. Therefore, the pressure of the pressure oil in the introduction oil passage 35 rises with almost no decrease due to the existence of the surge pressure release oil passage 33 whose flow rate is restricted by the opening throttle 34, and eventually the pressure switch 31 performs the detection operation. To be done.

The controller 24 receiving the detection signal from the pressure switch 31 causes the overhanging valve unit 21b to stop the supply of the pressure oil to each overhanging cylinder 16. Furthermore, the switching valve 23a is returned to the neutral position. In this way, the extension of each jack 15b is completed. After that, when an operation signal is input to the controller 24 through the operation of an operation means (not shown), the controller 24 switches the switching valve 23a to the right moving position, so that each jack cylinder 17 can be grounded.

Although the operation of the jack 15b is extended here, the hydraulic pressure detection device 30 detects the surge pressure of the pressure oil generated during storage activation and during storage operation even when the jack 15b is retracted. It is possible to detect that the overhanging cylinder 16 has reached the stroke end (reduction side) without being affected. Therefore, the automatic overhang device 20 can reliably perform the automatic storage operation of the jack 15b.

[0023]

[Effect of device]

 As described above, in the hydraulic pressure detecting device of the present invention, the surge pressure of the pressure oil that has momentarily increased to a predetermined pressure or higher is released to the tank through the surge pressure release oil passage, and the pressure switch detects the surge pressure. It will not be done. On the other hand, the pressure that is constantly maintained above the predetermined pressure is detected and operated by the pressure switch with almost no decrease due to the presence of the surge pressure release oil passage. Therefore, if this hydraulic pressure detection device is used, for example, to determine that the operation of the hydraulic actuator has reached the stroke end, surge pressure may be generated at the start of operation of this hydraulic actuator or during the stroke. Without being affected, it is possible to detect only the pressure rise state due to reaching the stroke end. As described above, by using the present hydraulic pressure detection device, it is possible to improve the reliability of the control device that controls the hydraulic actuator or the like based on the pressure force of the pressure oil.

[Brief description of drawings]

FIG. 1 is a perspective view of an aerial work vehicle equipped with an oil pressure detection device according to the present invention.

FIG. 2 is a configuration diagram of the oil pressure detection device.

[Explanation of symbols]

 16 Overhanging Cylinder 17 Jack Cylinder 20 Automatic Overhanging Device 23a Switching Valve 24 Controller 30 Hydraulic Pressure Detection Device 31 Pressure Switch 33 Surge Pressure Relief Oil Path 34 Opening Throttle

Claims (1)

[Scope of utility model registration request] 1. A hydraulic pressure detection device for detecting that the pressure of pressure oil supplied to a hydraulic actuator has reached a predetermined pressure, wherein a part of the pressure oil supplied to the hydraulic actuator is guided to the predetermined pressure. A pressure switch that is detected and operated by the pressure of the pressure oil that has reached a pressure, and is connected to an oil tank by branching from the introduction oil passage that guides the pressure oil to this pressure switch, and is smaller than the minimum passage area of the introduction oil passage. A hydraulic pressure detecting device comprising: a surge pressure releasing oil passage provided with a throttle portion having a passage area.