JP2008116021A - Control circuit for hydraulic actuator operating speed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a load on a hydraulic pump in a control circuit for hydraulic actuator operating speed which adjusts an amount of pressurized oil supplied from the hydraulic pump to a hydraulic actuator, and an amount of drain of the hydraulic actuator so that position control for a pilot pressure operation type variable throttle valve is made, and also to reduce a cost and a size by reducing the number of components. <P>SOLUTION: The other supply line 790 which is regulated at a designated pressure so as to supply working oil to a hydraulic mechanism having the other hydraulic actuator 300 different from the hydraulic actuator 60 and the other hydraulic actuator 600 fluidally driving the other hydraulic actuator 300 is fluidally connected with primary sides of electromagnetic proportional pressure regulators 760 and 765 fluidally connected with a pilot line 750 for giving pilot pressure to the variable throttle valve 740 on a secondary side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention adjusts the amount of pressure oil supplied when supplying hydraulic oil from a hydraulic pump to a hydraulic actuator and the amount of drain when discharging hydraulic oil from the hydraulic actuator by position control of a pilot pressure operated variable throttle valve. The hydraulic actuator operating speed control circuit is configured to control the operating speed of the hydraulic actuator.

  As a hydraulic mechanism that controls the operating speed of the hydraulic actuator by adjusting the pressure oil supply amount when supplying the hydraulic oil from the hydraulic pump to the hydraulic actuator and the drain amount when discharging the hydraulic oil from the hydraulic actuator, a pilot One using a pressure-actuated variable throttle valve has been proposed (see Patent Document 1 below).

Specifically, the hydraulic mechanism described in Patent Document 1 includes a supply line that supplies pressure oil from a hydraulic pump to a hydraulic actuator, a direction switching valve that selectively connects or disconnects the supply line, and the direction switching valve. And a drain line communicating with the supply line between the hydraulic actuators, a pilot pressure actuated variable throttle valve inserted in the drain line, and a pilot for applying a pilot pressure to the variable throttle valve And an electromagnetic proportional pressure reducing valve for adjusting the pressure oil supply to the pilot line.
The conventional hydraulic mechanism can adjust the pressure oil supply amount to the actuator and the drain amount from the actuator without inserting the electromagnetic proportional pressure reducing valve in the supply / discharge line of the hydraulic actuator. This is useful in that the operating speed of the hydraulic actuator can be controlled within a sufficient range without increasing the size of the valve.

However, in the conventional hydraulic mechanism, since a part of the pressure oil in the supply line is taken out and supplied to the primary side of the electromagnetic proportional pressure reducing valve, the variable throttle valve is operated. Regardless of whether or not, there is a problem that a load is always applied to the hydraulic pump.
That is, in the conventional hydraulic mechanism, a part of the pressure oil in the supply line is branched to the pilot pressure extraction line via the flow rate adjustment valve, and the pressure oil in the pilot pressure extraction line is regulated by the relief valve Is configured to supply to the primary side of the electromagnetic proportional pressure reducing valve.
In such a configuration, even when the variable throttle valve is not operated, a certain amount of pressure oil always flows through the pilot pressure extraction line, and an unnecessary load is constantly applied to the hydraulic pump.

Further, in the conventional configuration, the flow rate adjusting valve for taking out the pressure oil to the pilot pressure take-out line and the relief valve for setting the oil pressure of the pilot pressure take-out line are necessary, and the cost due to an increase in the number of parts is required. There is also the problem of incurring high and large size.
JP-A-6-280815

  The present invention has been made in view of the prior art, and by controlling the position of a pilot pressure actuated variable throttle valve, the amount of pressure oil supplied from the hydraulic pump to the hydraulic actuator and the amount of drain from the hydraulic actuator are reduced. Provided is an adjustable hydraulic actuator operation speed control circuit, which can reduce the load on the hydraulic pump and can reduce the cost and size by reducing the number of parts. One purpose.

  In order to solve the above problems, the present invention provides a supply line that supplies hydraulic oil from a hydraulic pump that is operatively driven by an engine to a hydraulic actuator, and a direction switching valve that selectively connects or disconnects the supply line. A drain line communicating with the supply line between the direction switching valve and the hydraulic actuator, a pilot pressure-operated variable throttle valve inserted in the drain line, and a pilot for the variable throttle valve A pilot line for applying pressure, and an electromagnetic proportional pressure reducing valve that adjusts the supply of pressure oil to the pilot line, and is output from the secondary side of the electromagnetic proportional pressure reducing valve, and the hydraulic pressure of the pressure oil flowing through the pilot line The operating degree of the hydraulic actuator is controlled by changing the throttle degree of the variable throttle valve by adjusting A pressure actuator operating speed control circuit, wherein the hydraulic pressure is set to a predetermined pressure to supply hydraulic oil to a hydraulic mechanism having another hydraulic actuator different from the hydraulic actuator and another hydraulic pump that fluidly drives the other hydraulic actuator. A hydraulic actuator operating speed control circuit is provided in which another regulated supply line is fluidly connected to the primary side of the electromagnetic proportional pressure reducing valve.

  The present invention also provides a pair of HSTs inserted in the traveling system transmission path so as to drive a pair of left and right drive wheels, respectively, and a first and a second driven by a pump shaft in the pair of HSTs. A second hydraulic pump, a charge line for supplying pressure oil from the second hydraulic pump to the pair of HSTs while being regulated to a predetermined pressure, a working machine, and a hydraulic actuator for raising and lowering the working machine, A hydraulic actuator operating speed control circuit applied to a work vehicle including a supply line for supplying pressure oil from the first hydraulic pump to the hydraulic actuator, wherein the supply line is selectively communicated or cut off. A switching valve, a drain line communicating with the supply line between the direction switching valve and the hydraulic actuator, and the drain line Comprising an pilot pressure-operating variable throttle valve, a pilot line for applying a pilot pressure to the variable throttle valve, and an electromagnetic proportional pressure reducing valve for adjusting pressure oil supply to the pilot line, A hydraulic actuator operating speed control circuit fluidly connected to a primary side of the electromagnetic proportional pressure reducing valve is provided.

According to the present invention, the pilot line that applies the pilot pressure to the pilot pressure actuated variable throttle valve that controls the operation speed of the hydraulic actuator is regulated to a predetermined pressure in order to supply hydraulic oil to the HST. Since pressure oil is supplied from the charge line, it is possible to reduce the load on the hydraulic pump serving as the hydraulic pressure source of the hydraulic actuator.
Also, compared with the conventional configuration in which the pressure oil for flowing to the pilot line is taken out from the supply line for supplying the pressure oil from the hydraulic pump to the hydraulic actuator, the flow control valve and the relief valve for setting the pilot pressure Can be eliminated. Therefore, cost reduction and size reduction can be achieved by reducing the number of parts.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
1 and 2 are a side view and a hydraulic circuit diagram of a tractor 1 to which an embodiment of a hydraulic actuator operating speed control circuit according to the present invention is applied, respectively.

First, the tractor 1 will be described.
As shown in FIGS. 1 and 2, the tractor 1 includes a body frame 10, an engine 20 supported by the body frame 10, and a pair of left and right first and second disposed on one side in the vehicle longitudinal direction. Drive wheels 30a and 30b (front wheels in the present embodiment), HST 100 inserted in a traveling system transmission path from engine 20 to drive wheels 30a and 30b, and the other side in the vehicle longitudinal direction Non-driving wheel 40 (a caster wheel that forms a rear wheel in the present embodiment), a working machine 50 that is operatively driven by the engine 20, a hydraulic lifting device 60 that lifts and lowers the working machine 50, And a first hydraulic pump 500 acting as a hydraulic source of the hydraulic lifting device 60.

As shown in FIG. 1, in the present embodiment, the tractor 1 is an articulate body.
Specifically, the fuselage frame 10 includes a first frame 11 disposed on one side in the vehicle front-rear direction (front in the present embodiment) and the other side in the vehicle front-rear direction (rear in the present embodiment). And a second frame 12 that is swingably connected to the first frame 11 so as to be swingable about a pivot shaft 15 along a substantially vertical direction.
The tractor 1 further swings the first frame 11 about the pivot shaft 10 with respect to the second frame 12 in conjunction with a steering member 5 such as a steering wheel that can be manually operated. A hydraulic steering mechanism (not shown) is provided.

The HST 100 includes an HST pump main body 220 that is operatively driven by the engine 20, and an HST motor main body 320 that is fluidly driven by the HST pump main body 220 and operatively drives the drive wheels 30. ing.
At least one of the HST pump main body 220 and the HST motor main body 320 is a variable displacement type. In the present embodiment, as shown in FIG. 2, the HST pump main body 220 is a variable displacement type, and the HST motor main body 320 is a fixed displacement type.

  In the present embodiment, as shown in FIG. 2, the HST 100 includes a first HST 100a corresponding to one of the pair of driving wheels 30a and 30b (for example, the left driving wheel 30a) and the pair of driving wheels 30a and 30b. The second HST 100b corresponding to the other (for example, the right drive wheel 30b).

The first HST 100a includes a first HST pump main body 220a that is operatively driven by the engine 20, and a first HST motor main body 320a that is fluidly connected to the first HST pump main body 220a via a pair of first hydraulic oil lines 400a. The first HST motor main body 320a that operatively drives the corresponding first driving wheel 30a.
The second HST 100b includes a second HST pump main body 220b operatively driven by the engine 20, and a second HST motor main body 320b fluidly connected to the second HST pump main body 220b via a pair of second hydraulic oil lines 400b. The second HST motor main body 320b that operatively drives the corresponding second driving wheel 30b.

In the present embodiment, the first and second HST motor bodies 320a and 320b are constituent members of a pair of wheel motor devices 80a and 80b that are close to the corresponding drive wheels 30a and 30b, respectively.
That is, the working vehicle 1 is separated from the hydraulic pump unit 200 including the first and second HST pump bodies 220a and 220b and the hydraulic pump unit 200 so as to be disposed close to the corresponding first drive wheel 30a. The first wheel motor device 80a is disposed, and the second wheel motor device 80b is disposed so as to be spaced from the hydraulic pump unit 200 so as to be disposed close to the corresponding second drive wheel 30b.

The hydraulic pump unit 200 includes first and second pump shafts 210a and 210b operatively connected to an output shaft of the engine 20, and the first HST pump supported by the first pump shaft 210a so as not to be relatively rotatable. A main body 220a, the second HST pump main body 220b supported by the second pump shaft 210b so as not to be relatively rotatable, a pump case 250 for housing the first and second HST pump main bodies 220a and 220b, and the first HST pump main body A first output adjustment member 230a that changes the suction / discharge amount of 220a and a second output adjustment member 230b that changes the suction / discharge amount of the second HST pump body 220b are provided.
In the present embodiment, as shown in FIG. 1, the hydraulic pump unit 100 is integrally connected to the engine 20 via a mounting member 150.

As shown in FIGS. 1 and 2, in the present embodiment, the first hydraulic pump 500 is attached to the hydraulic pump unit 200.
Specifically, the first hydraulic pump 500 includes a first hydraulic pump body 510 that is operatively driven to rotate by the engine 20, and a first pump case 520 that houses the first hydraulic pump body 510. Yes.
In the present embodiment, the first hydraulic pump body 510 is operatively rotated by one of the first and second pump shafts 210a and 210b (for example, the first pump shaft 210a), as shown in FIG. It is designed to be driven.

Furthermore, a second hydraulic pump 600 is attached to the hydraulic pump unit 200.
As shown in FIG. 2, the second hydraulic pump 600 acts as a charge pump for supplying hydraulic oil to the first and second HSTs 100a and 100b.
Specifically, the second hydraulic pump 600 includes a second hydraulic pump body 610 that is operatively driven to rotate by the engine 20, and a second pump case 620 that houses the second hydraulic pump body 610. Yes.
In the present embodiment, as shown in FIG. 2, the second hydraulic pump body 610 is rotationally driven by the other of the first and second pump shafts 210a and 210b (for example, the second pump shaft 210b). It has come to be.

  The first and second wheel motor devices 80a and 80b have substantially the same configuration. Accordingly, the constituent members of the second wheel motor device 80b are given the same reference numerals as the constituent members in the first wheel motor device 80a or the same reference numerals with the end of the reference numerals changed to b, and detailed description thereof is omitted. To do.

The first wheel motor device 80a includes a hydraulic motor unit 300 including the first HST motor body 320b.
The hydraulic motor unit 300 includes a first HST motor main body 320a, a motor shaft 310 that supports the first HST motor main body 320a so as not to be relatively rotatable, a motor case 350 that houses the first HST motor main body 310, and the first HST motor main body 320a. And a fixed swash plate (not shown) that defines the amount of oil supplied and discharged from the hydraulic HST main body 320a.

In such a configuration, the first HST motor main body 320a is fluidly connected to the first HST pump main body 220a via a pair of first hydraulic oil lines 400a, and is fluidly driven by the first HST pump main body 220a. It is like that.
Similarly, the second HST motor main body 320b is fluidly connected to the second HST pump main body 220b via a pair of second hydraulic oil lines 400b, and is fluidly driven by the second HST pump main body 220b. It has become.

Next, the hydraulic line in the HST 100 will be described.
The HST 100 fluidly connects the pair of first hydraulic fluid lines 400a fluidly connecting the first HST pump body 220a and the first HST motor body 320a, and the second HST pump body 220b and the second HST motor body 320b. A pair of second hydraulic oil lines 400b, a suction line 450 for fluidly connecting the suction sides of the first and second hydraulic pump bodies 510 and 610 to the oil sump 90, and pressure oil from the second hydraulic pump body 610 are used. And a charge line 410 for supplying the first hydraulic oil line 400a and the second hydraulic oil line 400b.

The charge line 410 is configured to supply pressure oil from the second hydraulic pump body 610 to the first and second hydraulic oil lines 400a and 400b in a state where the pressure oil is adjusted to a predetermined charge pressure.
Specifically, a charge relief valve 415 for setting a charge pressure is inserted in the charge line 410.
Further, the charge line 410 has a check valve that allows inflow of pressure oil from the second hydraulic pump body 610 to the first and second hydraulic oil lines 400a and 400b and prevents reverse flow. 416 is inserted.

  In the present embodiment, as shown in FIG. 2, the first and second HSTs 100a and 100b include one of a pair of first hydraulic oil lines 400a and one of a pair of second hydraulic oil lines 400b, respectively. When the pressure becomes abnormally high, a relief line 420 is provided for allowing the hydraulic oil in one hydraulic oil line to flow into the other hydraulic oil line.

  Further, in the present embodiment, as shown in FIG. 2, the HST 100 is provided with a drain line 430 for discharging the stored oil in the pump case 250 to the oil sump 90. Preferably, an oil cooler 435 is inserted in the drain line 430. 2 is a bypass line for preventing the inside of the pump case 250 from becoming an abnormally high pressure when the oil cooler 435 is clogged.

Here, the hydraulic actuator operation speed control circuit according to the present embodiment will be described.
The hydraulic actuator operating speed control circuit is applied to a work vehicle such as a tractor in order to control the operating speed of the hydraulic actuator.
In the present embodiment, the operating speed control circuit is configured to control the operating speed of the hydraulic lifting device 60.

  Specifically, as shown in FIG. 2, the operating speed control circuit includes a supply line 710 for supplying pressure oil from the first hydraulic pump 500 to the hydraulic lifting device 60 acting as the hydraulic actuator, and the supply line. A directional switching valve 720 for selectively communicating or blocking 710, a drain line 730 communicating with the supply line 710 between the directional switching valve 720 and the hydraulic actuator, and a pilot inserted in the drain line 730 A pressure-actuated variable throttle valve 740; a pilot line 750 for applying a pilot pressure to the variable throttle valve 740; and an electromagnetic proportional pressure reducing valve 760 for adjusting the pressure oil supply to the pilot line 750. Is output from the secondary side of the electromagnetic proportional pressure reducing valve 760 and flows through the pilot line 750. It is configured to control the operating speed of the variable throttle valve 740 of the aperture of the change the hydraulic lifting device 60 by adjusting the hydraulic pressure of that hydraulic fluid.

  As shown in FIG. 2, the variable throttle valve 740 can take a shut-off state in which the drain line 730 is shut off and a variable throttle state in which the communication width of the drain line 730 is changed according to the pilot pressure. ing.

  Since the electromagnetic proportional pressure reducing valve 760 is not inserted in the supply / discharge line of the hydraulic lifting / lowering device 60, the operating speed control circuit having such a configuration does not increase the size of the electromagnetic proportional pressure reducing valve 760. The operating speed of the lifting device 60 can be controlled within a sufficient range.

  In addition to the above configuration, the operating speed control circuit allows a flow of hydraulic oil from the relief valve 715 for setting the hydraulic pressure of the supply line 710 and the hydraulic actuator from the first hydraulic pump 500 to the hydraulic actuator and vice versa. A check valve 770 inserted in the supply line 710 between the direction switching valve 720 and the hydraulic actuator so as to prevent a flow in the direction, and the supply line 710 when the supply line 710 becomes abnormally high in pressure. And an unload valve 780 for discharging the pressurized oil therein to the oil reservoir 90.

Further, in the present embodiment, as shown in FIG. 2, the direction switching valve 720 also has a pilot pressure actuated variable throttle function.
That is, the direction switching valve 720 includes a shut-off state in which the hydraulic oil supply from the first hydraulic pump 500 to the hydraulic actuator is shut off, and a variable throttle state in which the communication width of the supply line 710 is changed according to a pilot pressure. Can be taken.
Therefore, in addition to the above-described configuration, the operating speed control circuit includes a second pilot line 755 for applying a pilot pressure to the variable throttle type directional switching valve 720, and pressure oil to the second pilot line 755. And a second electromagnetic proportional pressure reducing valve 765 for adjusting the supply.

  The operating speed control circuit according to the present embodiment is a hydraulic mechanism having, in addition to the above configuration, another hydraulic actuator different from the hydraulic lifting device 60 and a hydraulic pump that hydraulically drives the other hydraulic actuator. The hydraulic oil is configured to be supplied to the pilot line 750 (and the second pilot line 755) using the hydraulic oil.

  Specifically, as shown in FIG. 2, the operating speed control circuit connects the charge line 410 for supplying hydraulic oil to the HST 100 via the connection line 790 to the electromagnetic proportional pressure reducing valve 760 (and The second electromagnetic proportional pressure reducing valve 765) is fluidly connected to the primary side, thereby reducing the load on the first hydraulic pump 500, and for the flow rate adjusting valve and the pilot line that have been conventionally required. This eliminates the need for relief valves.

  That is, the conventional operation speed control circuit of the type in which the electromagnetic proportional pressure reducing valve is not inserted in the supply / discharge line of the hydraulic actuator extracts a part of the pressure oil in the supply line for supplying the hydraulic oil to the hydraulic actuator. The electromagnetic proportional pressure reducing valve is configured to be supplied to the primary side. Therefore, there is a problem that a load is always applied to the hydraulic pump serving as the hydraulic pressure source of the hydraulic actuator regardless of whether or not the variable throttle valve is operated.

Specifically, the conventional operating speed control circuit branches a part of the pressure oil in the supply line to the pilot pressure extraction line via the flow rate adjustment valve, and regulates the pressure oil in the pilot extraction line by the relief valve. In this state, the electromagnetic proportional pressure reducing valve is supplied to the primary side.
In such a configuration, even when the variable throttle valve is not operated, a certain amount of pressure oil always flows through the pilot pressure extraction line, which is unnecessary for the hydraulic pump serving as the hydraulic source of the hydraulic actuator. Load is always applied.
Further, in the conventional configuration, the flow rate adjusting valve for taking out the pressure oil to the pilot pressure take-out line and the relief valve for setting the oil pressure of the pilot pressure take-out line are necessary, and the cost due to the increase in the number of parts is required. There is also the problem of incurring high and large size.

On the other hand, in the present embodiment, as described above, the hydraulic oil from the charge line 410 adjusted to a predetermined pressure by the charge relief valve 415 to the pilot line 750 (and the second pilot line 755). (See FIG. 2 etc.).
Therefore, the load on the first hydraulic pump 500 can be reduced, and the flow rate adjusting valve and the relief valve for the pilot line can be made unnecessary.
The second hydraulic pump 600 acting as a charge pump is always supplied with a sufficient amount of pressure oil that can sufficiently supply hydraulic oil to the HST 100 from the second hydraulic pump 600, and surplus oil is supplied to the charge relief. Drained through valve 425.
Therefore, even if the hydraulic fluid for the pilot line 750 (and the second pilot line 755) is taken out from the charge line 410, the load on the second hydraulic pump 600 does not increase so much.

FIG. 1 is a perspective view of a tractor to which an embodiment of a hydraulic actuator operating speed control circuit according to the present invention is applied. FIG. 2 is a hydraulic circuit diagram of the tractor shown in FIG.

Explanation of symbols

1 Tractor (work vehicle)
20 Engine 60 Hydraulic lifting device (hydraulic actuator)
100a, 100b 1st HST, 2nd HST
220a, 220b First and second HST pumps (other hydraulic pumps)
320a, 320b first and second HST motors (other hydraulic actuators)
410 charge line 500 first hydraulic pump 600 second hydraulic pump 710 supply line 720 direction switching valve 730 drain line 740 variable throttle valve 750 pilot line 755 second pilot line 760 electromagnetic proportional pressure reducing valve 765 second electromagnetic proportional pressure reducing valve

Claims (2)

A supply line for supplying hydraulic oil from a hydraulic pump operatively driven by an engine to a hydraulic actuator, a direction switching valve for selectively communicating or blocking the supply line, and between the direction switching valve and the hydraulic actuator A drain line communicated with the supply line, a pilot pressure actuated variable throttle valve inserted in the drain line, a pilot line for applying a pilot pressure to the variable throttle valve, and the pilot line An electromagnetic proportional pressure reducing valve that adjusts the pressure oil supply to the throttle valve, and the throttle degree of the variable throttle valve is adjusted by adjusting the hydraulic pressure of the pressure oil that is output from the secondary side of the electromagnetic proportional pressure reducing valve and flows through the pilot line Hydraulic actuator operating speed control circuit configured to control the operating speed of the hydraulic actuator by changing There,
Another supply line regulated to a predetermined pressure to supply hydraulic oil to a hydraulic mechanism having another hydraulic actuator different from the hydraulic actuator and another hydraulic pump that fluidly drives the other hydraulic actuator A hydraulic actuator operating speed control circuit characterized in that it is fluidly connected to the primary side of an electromagnetic proportional pressure reducing valve. A pair of HSTs inserted in the traveling system transmission path so as to drive a pair of left and right drive wheels, respectively, and first and second hydraulic pumps operatively driven by pump shafts in the pair of HSTs, A charge line for supplying pressure oil from the second hydraulic pump to the pair of HSTs in a state adjusted to a predetermined pressure, a working machine, a hydraulic actuator for raising and lowering the working machine, and the first hydraulic pump A hydraulic actuator operating speed control circuit applied to a work vehicle including a supply line for supplying the hydraulic oil to the hydraulic actuator,
A direction switching valve for selectively communicating or shutting off the supply line, a drain line communicating with the supply line between the direction switching valve and the hydraulic actuator, and a pilot pressure operation type inserted in the drain line A variable throttle valve, a pilot line for applying a pilot pressure to the variable throttle valve, and an electromagnetic proportional pressure reducing valve for adjusting pressure oil supply to the pilot line,
A hydraulic actuator operating speed control circuit, wherein the charge line is fluidly connected to a primary side of the electromagnetic proportional pressure reducing valve.

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