JPS60249706A - Hydraulic control device - Google Patents

Abstract

PURPOSE:To attain good hydraulic control irrespective of a pump type, that is, a negative type or a positive type, by supplying a pressure oil to a regulator of a hydraulic pump via a pressure reducing valve unit formed by combining a pilot valve with a pressure reducing valve. CONSTITUTION:When a pilot valve 64 is pushed down to a position r, a pressure oil is supplied to a hydraulic pack 68 to bring a main selector valve into a condition C. At this time, a pressure oil from a check valve 82 is fed into a pilot port to increase pressure in a chamber and thereby extend a pressure reducing spring 40. When a signal is supplied from a hydraulic pump 56 to an external signal pressure port, a pressure reducing valve body 38 is displaced to a differential piston 44 side, and a piston 58a of a controller 58 is displaced by a resilient force of a coil spring 60 to increase a discharge amount of a hydraulic pump 80.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control device, and more particularly to a hydraulic control device that is attached to a variable displacement hydraulic pump and adjusts the amount of pressure oil discharged from the hydraulic pump regardless of its control type. This invention relates to a hydraulic control device that enables

2. Description of the Related Art Variable displacement hydraulic pumps that can adjust the discharge flow rate of pressure oil from a hydraulic pump by applying a pilot pressure signal to a regulator, that is, a controller from the outside, have been widely used. In this case, the regulator is a so-called positive controller capable of increasing the discharge flow rate from the hydraulic pump as the external pilot pressure increases, and a so-called positive controller capable of increasing the discharge flow rate of the hydraulic pump as the external pilot pressure decreases. It can be broadly divided into negative controllers. In this case, the type of controller is highly dependent on the type of pump. In other words, the pump structure is determined by whether a positive controller or a negative controller is employed.

In reality, these positive controllers and negative controllers are used depending on the purpose or application of each device.

However, the hydraulic control systems of various devices other than the positive controller or negative controller are common, and therefore, in some cases, it may be necessary to replace the positive controller with a negative controller, or replace a negative controller with a positive controller. There will be a request to do so. However, in the conventional technology, since the positive controller and negative controller have different pump structures of the hydraulic pumps in which the respective controllers are incorporated, it is necessary to rearrange the pump as a whole or give up on such a change. There was an inconvenience. Of course, even if it were possible to rearrange the sheet metal, it would impose a large financial burden, and there would also be the problem that the hydraulic line would have to be stopped for a considerable period of time, even temporarily. .

The present invention has been made in order to eliminate the various inconveniences mentioned above, and even when the control method of the hydraulic pump is different, it can be used simply by attaching it to the signal input part of the regulator that controls the discharge amount. It is an object of the present invention to provide a hydraulic control device capable of easily changing a negative recontrol method.

In order to achieve the above object, the present invention includes a variable displacement hydraulic pump, a switching valve connected to the discharge side of the hydraulic pump to supply pressure oil to an actuator, and a switching valve connected to the hydraulic pump to supply pressure oil to an actuator. A pressure reducing valve unit including a controller that controls the discharge pressure of the hydraulic pump based on a hydraulic signal, and that connects a pilot valve that controls a pressure oil supply passage to the switching valve and controls the supply of pressure oil to the controller. It is characterized by being configured to connect.

Next, preferred embodiments of the hydraulic control device according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a tank for supplying predetermined oil to a variable displacement positive type hydraulic pump 12. As shown in FIG. The output side of the hydraulic pump 12 is connected to a switching valve unit 14 . The switching valve unit 14 includes a main switching valve 16, a main relief valve 18, and a low pressure relief valve 20, and an actuator 22 is further connected to the main switching valve 16.

That is, the pipe line extending from the hydraulic pump 12 becomes a center bypass 24 inside the switching valve unit 14,
The primary side of the main relief valve 18 is the center bypass 2
Connected to 4. On the other hand, the center bypass 24 is configured such that the main switching valve 16 passes through the main switching valve 16 and is introduced into the low pressure relief valve 20 when the main switching valve 16 is in a neutral state. The low pressure relief valve 20 includes a check valve 26 and a throttle valve 28 therein, and the check valve 26 and the throttle valve 28 are arranged in parallel with each other, and the downstream side thereof is connected to the tank 30. In this case, the secondary side of the main relief valve 18 is also connected to the tank 30.

Next, in the center bypass 24, a pipe line is branched from upstream of the low pressure relief valve 20, and this pipe line is introduced into the pressure reducing valve unit 32.

Therefore, the detailed configuration of the pressure reducing valve unit 32 is shown in FIG. 2. That is, the pressure reducing valve unit 32 includes a body 34, a pressure reducing valve main body 38 slidably disposed in a hole 36 having a step formed in the center of the body 34, and one end of the pressure reducing valve main body 38. The differential piston 44 is basically comprised of a pressure reducing spring 40 that is locked to the pressure reducing spring 40, and a differential piston 44, one end of which engages with the pressure reducing spring 40 and a differential spring 42 seated and engaged with the other end. Note that the body 34 has a pilot port 46, a drain port 48, and an external signal pressure port 5.
0 and a reduced pressure secondary port 52 are formed.

On the other hand, a hydraulic pump 56 for supplying pressure oil from a tank 54 is attached to the external signal pressure port 50, and the secondary side of the pressure reducing valve unit 32 is connected to a controller 58.

The controller 58 has an elastic member, ie, a coil spring 60 disposed therein.
A rod 62 is extended outside the hydraulic pump 12, and the discharge amount of the hydraulic pump 12 is adjusted by this rod 62.

Next, a pilot valve 64 is interposed in the device of the present invention. One port of the viroft valve 64 is connected to one hydraulic pack 66 of the main switching valve 16, and the other port of the pilot valve 64 is connected to the other hydraulic pack 68 of the main switching valve 16. The viroft valve 64 can be opened and closed freely via a lever 70. The discharge side of the hydraulic pump 56 is connected to the input port. In addition,
In the figure, reference numeral 72 is a relief valve connected to the discharge side of the hydraulic pump 56, and reference numeral 74 is a hydraulic tank connected to the secondary side of the relief valve 72.

The hydraulic control device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

For example, when the lever 70 of the pilot valve 64 is maintained at the neutral position and the hydraulic pump 56 is driven, the hydraulic pump 56 pumps pressure oil from the tank 54 to the pressure reducing valve unit 3.
2 and the pilot valve 64. At this time, the hydraulic pump 12 is also rotated. When the lever 70 is in the neutral position, the main switching valve 16 occupies the neutral port, ie the position indicated by reference numeral A, since hydraulic oil of equal pressure is supplied to the hydraulic banks 66,68. Therefore, the pressure oil supplied by the hydraulic pump 12 is transferred to the center bypass 2.
4, is fed to the low pressure relief valve 2o, and is returned to the tank 30 via the check valve 26.

If the discharge amount of the hydraulic pump 12 is large, the relief valve 18 opens and the excess pressure oil is returned to the tank 30 in the same manner as described above.

By the way, by displacing the pilot valve 64 to the left (L side), the branched pressure oil of the hydraulic pump 56 enters the other hydraulic puncture 66 side, gradually increases the pressure against the main switching valve 16, and reaches a predetermined level. When the pressure reaches , the main switching valve 16 is completely switched to the state indicated by reference numeral B, and the hydraulic pump 12 is connected to the actuator 22. That is, the pressure oil that has passed through the center bypass 24 passes through the check valve in the main switching valve 16, reaches the actuator 22, and displaces the piston inside the actuator 22 in the direction of arrow X. In this case, when the main switching valve 16 is in state B, the port of the center bypass 24 to the low pressure relief valve 2o is blocked, so no pressure oil is supplied to it. Therefore, since there is no pressure oil branched from upstream of the low pressure relief valve 20, no hydraulic pressure is applied to the pilot port 46.

Therefore, the differential spring 42 sufficiently presses the differential piston 44, and the pressure reducing spring 40 is compressed. As a result, the pressure reducing valve main body 38 is pushed toward the secondary pressure port 52 side. Therefore, when the pressure oil supplied from the hydraulic pump 56 via the external signal pressure port 50 is introduced into the chamber 38a of the pressure reducing valve main body 38 sliding in the body 34, the pressure inside the chamber 38a is increases. However, the pressure of this pressure oil does not push the pressure reducing valve main body 38 against the elastic force of the pressure reducing spring 40, but rather increases the amount of pressure oil flowing out from the secondary pressure port 52 for pressure reduction. let As a result, the pressure oil increases in the controller 58, causing the piston 58a of the controller 58 to be displaced against the coil spring 60, so that the rod 62 increases the discharge amount of the hydraulic pump 12.

Next, another embodiment of the hydraulic control device according to the present invention is shown in FIG. In this case, the same reference numerals as in the above embodiment indicate the same components.

Therefore, in this embodiment, the hydraulic pump 80 is of a negative type, that is, a type in which the discharge flow rate decreases as the hydraulic pressure within the controller increases. The low pressure relief valve 20 incorporated in the above embodiment is omitted and the pilot valve 6 is replaced instead.
A check valve 82 is provided to allow only the higher pressure oil to flow through the pipes to the hydraulic punctures 66 and 68 of the four main switching valves 16.

Therefore, in this embodiment, when the lever 70 is in the neutral state, the check valve 80 is connected to the pressure reducing valve unit 32.
There is no pressure oil supply to the area.

Therefore, the differential piston 44 is pressed by the differential spring 42,
As in the previous embodiment, the pressure in the chamber 38a of the pressure reducing valve main body 38 is high, and sufficient pressure oil is supplied to the controller 58. That is, since the piston 58a of the controller 58 is displaced against the elastic force of the coil spring 60, the rod 62 is displaced in the direction of the arrow, thereby reducing the discharge amount of the pump 80.

On the other hand, if the pilot valve 64 is tilted to the right side (R side), for example, the main switching valve 16 reaches the C state because pressure oil is supplied to the hydraulic panchromator 8. At this time, check valve 82
Pressure oil from the chamber enters the pilot port 46 and increases the pressure in the chamber 46a. As a result, the differential piston 44 is displaced in a direction that compresses the differential spring 42 due to the increase in pressure within the chamber 46a, and as a result, the pressure reducing spring 40 is expanded. That is, when a signal from the hydraulic pump 56 enters the external signal pressure port 50, the hydraulic pressure in the chamber 38a increases, but since the pressure reducing spring 40 has already reduced its elastic force, the hydraulic pressure is reduced to the pressure reducing valve body. 3
8 toward the differential piston 44 side. As a result, the piston 58a of the controller 58 is displaced in the direction shown by the broken line arrow by the elastic force of the coil spring 60, so that the hydraulic pump 80 increases its discharge amount.

According to the present invention, as described above, by combining the pyro valve and the pressure reducing valve, it is possible to perform hydraulic control regardless of whether the hydraulic pump is a negative type or a positive type. Furthermore, since the device of the present invention has a simple configuration, it can be easily incorporated into various devices that have been used in the past, and is inexpensive, so the economic burden can be reduced.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design are possible without departing from the gist of the present invention. Of course.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of a hydraulic control device according to the present invention, and FIG.
The figure is a longitudinal sectional view of a pressure reducing valve unit incorporated in the device of the present invention, and FIG. 3 is a hydraulic circuit diagram showing another embodiment of the hydraulic control device according to the present invention. lO...Tank 12...Hydraulic pump 14...Switching valve unit 16...Main switching valve 18...Main relief valve 20...Low pressure relief valve 22...Actuator 24
... Center bypass 26.. Check valve 28.. Throttle valve 30.. Tank 32.. Pressure reducing valve unit 34.. Body 36.. Hole 38.. Pressure reducing valve body 38a.. Chamber 40.. Pressure reducing spring 42. -Differential spring 44...Differential piston 46...Pilot boat 46a...Chamber 48...Drain port 50...External signal pressure port 52...Secondary pressure port for pressure reduction 54...Tank 56...Hydraulic pump 58 ... Controller 58a ... Piston 60 ... Coil spring 62 ... Rod 64 ... Biloft valve 66 ... Hydraulic puncture 68 ... Hydraulic pack 70 ... Lever 72 ... Relief valve 74 ... Hydraulic tank 74 ... Pressure reducing valve Main body 74a...Chamber 76...Pilot port 78...Tren port 80...Hydraulic pump 82...Check valve Patent applicant Toshiba Machine Co., Ltd.

Claims (1)

[Scope of Claims] (1) A variable displacement expansion hydraulic pump, a switching valve connected to the discharge side of the hydraulic pump for supplying pressure oil to the actuator, and a switching valve connected to the hydraulic pump to respond to an external hydraulic signal. a controller that controls the discharge pressure of the hydraulic pump, a pilot valve that controls a pressure oil supply passage is connected to the switching valve, and a pressure reducing valve unit that controls the supply of pressure oil to the controller is connected. A hydraulic control device characterized by being configured as follows. (2. In the device according to claim 1, the hydraulic pump is of a positive type, and the pressure reducing valve unit supplies pressure oil from the upstream side of a low pressure relief valve connected to the center bypass passage of the hydraulic pump. (3) In the device according to claim 1, the hydraulic pump is of a negative type, and the pressure reducing valve unit is disposed downstream of the pilot valve. A hydraulic control device that achieves control of a controller by supplying pressure oil from a check valve that has been installed. (4) In the device according to any one of claims 1 to 3, a pressure reducing valve unit A hydraulic control device comprising a differential piston disposed within a body and pressed by a differential spring, and a pressure reducing spring interposed between the differential piston and a pressure reducing valve body.