JPH08100805A - Pressure control valve - Google Patents

Abstract

PURPOSE: To smoothly and stably control an actuator by providing a control oil pressure passage by which an operational oil is unloaded by communicating a port on the supplying side with a port on the discharge side at the time of a neutral position, and a regulation oil pressure passage for opening oil pressure chambers upstream and downstream from a pressure compensation valve less than a full communication opening. CONSTITUTION: Oil passages to an A port oil chamber 33 or a B port oil chamber 34 from a P port oil chamber 31 is closed in the neutral position, and a hydraulic motor 300 is stopped. An oil passage consisting of a main spool 11 and a casing 10 from the P port oil chamber 32 is opened, and then most of a pump discharge quantity is unloaded to a T port oil chamber 32. Operational oil from a hydraulic pump 201 flows in the A port oil chamber 33 in its oil quantity responding to a moving distance of a main spool 11, under an ON-load condition in which a pressure compensation function operates, and remaining oil flows by the pressure compensation spool 21 from a variable orifice 24 to the T port oil chamber 32. The variable orifice 24 is slightly opened reguadless of its nuetral position so as to make the operational oil flow, and it is smoothly transferred to the pressure compensation condition, and then startup of the hydraulic motor 300 without shock can be achieved.

Description

Detailed Description of the Invention

 ＄

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control valve used for starting and stopping hydraulic motors and hydraulic cylinders for marine hydraulic winches and construction machines, and for controlling rotation speed and speed. $

2. Description of the Related Art Conventionally, as a hydraulic control valve of this type, FIG.
And the one shown in FIG. FIG. 10 is a hydraulic circuit diagram of a conventional hydraulic control valve, and FIG. 11 is a detailed sectional view of the hydraulic control valve shown in FIG. In each of the above-mentioned drawings, a conventional hydraulic control valve is a flow rate control switching valve 1 for switching forward / backward of hydraulic fluid and a flow rate control for a hydraulic motor 300 or the like connected as a load, and the flow rate control switching valve 1. Is integrally combined with a pressure compensating valve 2 for compensating and controlling so that the pressure difference at 1 is almost constant. $ In the casing 10 of the flow rate adjustment switching valve 1, the hydraulic pump 201
This is a configuration in which an unloading oil passage 130 is formed to unload the hydraulic oil from the P port oil chamber 31 supplied from the to the T port oil chamber 32. The unloading oil passage 130 is used when a plurality of hydraulic actuators such as hydraulic motors are configured in a series circuit, and the configuration can be simplified and the cost of the device itself can be reduced. Next, the operation of the conventional hydraulic control valve based on the above configuration will be described. $ First, the hydraulic oil flowing in from the hydraulic pump 201 is the P port oil chamber 3 in the figure.
1 through the unload oil passage 130 provided in the casing 10 of the flow rate control switching valve 1, the main spool oil passage 113 formed by the casing 10 and the main spool 11, and the unloading oil to the T port oil chamber 32. To load.
Further, the hydraulic oil in the T port oil chamber 32 passes through a pipe (not shown) connected to the flow rate adjustment switching valve 1 and enters the P port oil chamber 31 of the next stage flow rate adjustment switching valve. $ Also, hydraulic motor 3
When a hydraulic actuator such as 00 is driven, the operation lever 12 is operated to operate the P port oil chamber 3 of the flow rate adjustment switching valve 1.
The hydraulic oil flowing into No. 1 is caused to flow into the A port oil chamber 33, the hydraulic motor 300 is driven, and the hydraulic oil returned from this hydraulic motor 300 is caused to flow into the B port oil chamber 34. The hydraulic oil in the B port oil chamber 34 flows through the main spool oil passage 113a formed by the casing 10 and the main spool 11 to the T port oil chamber 32, and from the T port oil chamber 32 to the flow rate adjustment switching valve of the next stage. Enter and finally return to the oil tank 200. Further, in order to control the speed of the hydraulic actuator such as the hydraulic motor 300, the amount of oil from the P port oil chamber 31 to the A port oil chamber 33 is adjusted according to the area of the oil groove formed in the main spool 11. The pressure compensating valve 2 having a pressure compensating mechanism that automatically adjusts even if the pressure changes, causes excess hydraulic oil to flow from the P port oil chamber 31 to the variable orifice 24 composed of the pressure compensating spool 21 and the casing 10. Discharge to the hydraulic chamber 32. $

Since the conventional hydraulic control valve is configured as described above, the main spool oil passage formed by the casing 10 and the main spool 11 regardless of the amount of hydraulic oil that flows in. The entire amount of hydraulic oil is unloaded into the T port oil chamber 32 through 113a, and in the unload state when the hydraulic motor 300 (hydraulic actuator) is stopped, the hydraulic compensation valve 2
Variable orifice 24 is closed. Hydraulic motor 300
When the main spool 11 is operated to activate a part of the hydraulic oil in the P port oil chamber 31 to the A port oil chamber 33, the hydraulic oil remaining in the P port oil chamber 31 is released from the pressure compensating valve 2.
Must be returned to the T port oil chamber 32 through the variable orifice 24 of When the main spool 11 is operated, the variable orifice 24 is in a closed state, and by the time the variable orifice 24 is opened, the entire amount of hydraulic oil flowing into the P port oil chamber 31 flows to the A port oil chamber 33. It flows to the hydraulic motor 300 side which is a hydraulic actuator. $ When the entire amount of hydraulic oil in the P port oil chamber 31 flows into the A port oil chamber 31 in this way, the hydraulic motor 30 is temporarily
The overspeed becomes 0, and the valve does not function as a flow rate control valve for speed control. As the jumping phenomenon of the switching valve with the flow rate adjusting function, the overspeed of the hydraulic motor 300 and the operation lever 12 are operated to operate the hydraulic motor 3.
00 has a problem that a smooth control operation cannot be performed because a shock caused by the switching operation is accompanied by a pressure increase in the hydraulic circuit until 00 normally operates. In other words, it is generally desirable for the machine driven by the hydraulic motor 300 to gradually increase the speed from the stopped state, but temporarily it suddenly starts moving from the stopped state and then gradually increases the speed, which is extremely unstable. There is a problem of driving control. The present invention has been made to solve the above problems, and an object of the present invention is to provide a hydraulic control valve that can smoothly and stably drive and control a hydraulic actuator. $

A hydraulic control device according to the present invention outputs hydraulic oil from an upstream port to a downstream side via any one of a plurality of switching ports, and loads the plurality of hydraulic oils from a load side. A directional control valve that inputs through any one of the switching ports, and switches the flow direction of the hydraulic oil in the plurality of switching ports by moving the main spool;
The hydraulic oil flowing through the directional control valve is set according to the equilibrium condition between the upstream hydraulic chamber connected to the supply port and the spring hydraulic chamber connected to the discharge port to which a predetermined pressure is applied by the spring force. In a hydraulic control device including a pressure compensation valve that adjusts to a substantially constant value, a casing of the directional control valve and a main spool are formed at a neutral time when the outflow of hydraulic oil to the load side is stopped. A control hydraulic path that communicates the port and unloads hydraulic oil,
An adjusting hydraulic passage that opens the upstream side hydraulic chamber and the downstream side hydraulic chamber of the pressure compensating valve to less than the total communication opening degree at the neutral state is provided. In addition, the hydraulic control device according to the present invention optionally sets the set pressure of the spring when the pressure compensating valve communicates the upstream hydraulic chamber and the downstream hydraulic chamber with the passage hydraulic pressure of the main spool of the directional control valve. It is set to be smaller than the magnitude of pressure loss in the passage. $

In the present invention, the control oil pressure passage is formed between the casing of the directional control valve and the main spool of the directional control valve at the time of neutrality so that the supply side port and the discharge side port are communicated with each other and the hydraulic oil is removed. Since the adjustment hydraulic passage that connects the upstream side hydraulic chamber and the downstream side hydraulic chamber of the pressure compensating valve is opened at a smaller opening than the full communication opening while loading, the oil passage formed on the main spool The pressure loss during unloading can be reduced as much as possible, and smooth and stable hydraulic control can be performed. Further, since the control hydraulic passage at the time of unloading is formed between the casing of the directional control valve and the main spool, the entire apparatus can be downsized. Further, in the present invention, when the pressure compensating valve communicates the upstream side hydraulic chamber and the downstream side hydraulic chamber, the set pressure of the spring of the pressure compensating valve is set to the pressure loss of the passage hydraulic passage of the main spool of the directional control valve. Since the size is set smaller than the size, the hydraulic control during unloading can be further facilitated. $

【Example】

(One Embodiment of the Present Invention) One embodiment of the present invention will be described below with reference to FIGS. 1 is a schematic hydraulic circuit diagram of a hydraulic control valve according to the present embodiment, FIGS. 2 to 5 are sectional views of the hydraulic control valve according to the present embodiment in various operating states, and FIGS. It is each operation characteristic view of the hydraulic control valve which concerns. In each of the drawings, the hydraulic control valve according to the present embodiment includes a flow rate control switching valve 1 for switching the inflow / outflow of hydraulic oil by the main spool 11 slidingly moving in the casing 10 by operating the operation lever 12. Flow rate adjustment switching valve 1
And a pressure compensating valve 2 for compensating the pressure fluctuation of the P port oil chamber 31 from the main spool oil passage 112 formed by the casing 10 and the main spool 11.
The port side oil chamber 32 is unloaded, and at the time of this unloading, the spring side oil chamber 211 of the pressure compensation valve 2 is moved to the main spool oil passage 11 formed in the main spool 11.
5 to the T port oil chamber 32, and the anti-spring side oil chamber 212 of the pressure compensating valve 2 is connected to the P port oil chamber 31 via a pressure compensating spool oil passage 231 formed in the pressure compensating spool 21. It is configured to be connected to. On the side wall of the casing 10 on the side of the pressure compensating valve 2 in the P port oil chamber 31, the expanded step portions 31a, 31b, 32a.
32b is formed. In addition, the spring 22 has its set value set according to the flow rate of the hydraulic oil discharged from the hydraulic pump 201 and the casing 10 and the main spool 1.
It is a configuration adapted to the value of the pressure loss generated between 1 and 1. $ Spring side oil chamber 21 at the time of unloading
The connection between 1 and the T port oil chamber 32 is such that the main spool 11 is in the neutral position during unloading, and the main spool oil passage 115, the casing oil passage 102, and the casing oil passage 10 are connected.
3 and 3 communicate with each other, and the oil is communicated through the oil passages 102, 103, 115 and the casing oil passage 25 which communicate with each other. Further, the connection between the anti-spring side oil chamber 212 and the P port oil chamber 31 during the unloading is
The pressure compensating spool orifice 23 communicates with the P port oil chamber 32, and the pressure compensating spool orifice 23 and the pressure compensating spool oil passage 231 are provided. Further, when the vehicle is on-road, the main spool 11 moves from the neutral position and the main spool oil passage 115 formed in the main spool 11 is displaced from the casing oil passage 102 and the casing oil passage 103, and the spring side oil is discharged. The chamber 221 and the P port oil chamber 31 are shut off, and the P port oil chamber 31 is connected to the A port chamber 33 (or the B port chamber 34) on the side where the hydraulic actuator such as the hydraulic motor 300 is connected to perform pressure compensation. Configured as a mechanism. Next, the operation of this embodiment based on the above configuration will be described. In FIG. 2, the hydraulic oil flowing into the P port oil chamber 31 passes through the oil passages in the casing 10 and the main spool oil passages 110, 11 provided in the main spool 11.
After passing through Nos. 1 and 113, it flows into the T port oil chamber 32 and flows out. In this case, a pressure loss for passage is generated depending on the area of each oil passage provided and the amount of hydraulic oil passing through. This pressure loss is ΔP (Kgf / cm ² ) = (Q / C ·
A) ² . Here, Q is the amount of oil, C is the flow coefficient, and A is the area of the passing throttle. This pressure loss ΔP is proportional to the square of the amount of oil and inversely proportional to the square of the area. $ Again
Loss power is loss power H (KW) = (△ P × Q) / 621
Is expressed as the product of pressure loss and oil amount. Where ΔP is
Kgf / cm ² , Q is L / min. Since the power loss is proportional to the oil amount and the pressure loss in this way, it is desirable to suppress the pressure loss under a constant oil amount condition. In the hydraulic control valve according to the present embodiment, the amount of oil used in the hydraulic control valve is detected, and when the amount of oil exceeds a preset amount, the pressure compensation spool 21 is pushed up together with the oil passage provided in the main spool 11. The variable orifice 24 is also unloaded. In this way, the main spool 11 side and the pressure compensation spool 21
Since it is possible to unload from the two flow passages, the pressure loss at the time of unloading due to the oil passage provided on the main spool 11 can be suppressed to the maximum, and the main passage that forms the oil passage area can be suppressed. The spool 11 and the casing 10 can be compactly accommodated. $ That is, the pressure loss only in the oil passage provided in the main spool 11 is proportional to the square of the oil amount, and therefore the pressure loss remarkably increases as the oil amount increases, but when the oil amount exceeds the set value, the pressure amount decreases. Unloading by the compensation spool 21 is added. Also,
Even if the amount of oil further increases, the variable orifice 24 opens at an opening proportional to the amount of oil, so that the pressure loss can be kept low, and a compact hydraulic control valve with low pressure loss can be configured (see FIG. 6). Further, in the case of unloading only with the pressure compensating spool 21, as shown by the chain double-dashed line in FIG. 6, a pressure sufficient to push up the spring for forming the oil passage to open the variable orifice 24 is required, regardless of the oil amount. There is a pressure loss proportional to the initial set pressure. $ The position of the pressure compensation spool 21 in the unloading state has a great influence on the transient state when the hydraulic motor 300 is operated. That is, in the method of unloading through the oil passage by the pressure compensation spool 21, the oil passage has a variable orifice 24.
As such, the variable orifice 24 requires a large passage area. In order to carry out the on-load from this state, the main spool 11 is operated to switch the hydraulic oil in the P port oil chamber 31 to the A port oil chamber 33 or the B port oil chamber 34, and either the A port or the B port oil chamber Hydraulic oil is supplied from 33 and 34 to the spring side oil chamber 211 through the casing orifice 101, and the spring 22 operates to close the variable orifice 24. At this time, it is installed to provide stability in an operating state. The casing orifice 101, which operates to delay the closing of the variable orifice 24 by the pressure compensation spool 21, delays the operation of the hydraulic motor 300. Further, when the hydraulic motor 300 is switched from the operating state to the unloading state, in the operating state, the pressure compensating spool 21 closes the variable orifice 24 as shown in FIG. 2, and the working oil is transferred from the P port oil chamber 31 to the main spool. 11 flows out to the A port oil chamber 33 or the B port oil chamber 34. $ Main spool 1
1 to move the P port oil chamber 31 to the A port oil chamber 33
Alternatively, when the oil passage to the B port oil chamber 34 is closed, the working oil in the spring-side oil chamber 211 is discharged from the casing orifice 10
1, the casing oil passages 106, 102, the main spool oil passage 115 and the casing oil passage 103 are connected to the low pressure side, but since the variable orifice 24 is in the closed state, the hydraulic oil from the P port oil chamber 31 is It loses its place of departure and pressure rises abnormally. When the pressure in the P port oil chamber 31 rises, the pressure compensating spool 21 compresses the spring side oil chamber 211 via the pressure compensating spool orifice 23 and the pressure compensating spool oil passage 231, and the working oil in the spring side oil chamber 211 is transferred to the casing. Orifice 101, casing oil passage 1
06, 102, the main spool oil passage 115, and the casing oil passage 103 to discharge to the low-pressure side T port oil chamber 32 to open the variable orifice 24 to form an unload state. In the present embodiment, it is not necessary to open the variable orifice 24 by the pressure compensation spool 21 largely for unloading, and the main spool 11 up to the set oil amount as shown in FIG.
The unloading in the oil passage is performed, and when the set oil amount is exceeded, the variable orifice 24 of the pressure compensation spool 21 is opened by a required opening proportional to the oil amount, and the unloading is performed together with the main spool 11. At this time, in the pressure compensating spool 21, as shown in FIG. 7, when the amount of oil is set, the spool stroke position is in the zero overlap state with the opening value of the variable orifice 24 being zero, and the amount of oil is increased and the opening area is increased. The stroke also becomes large. Further, when the amount of oil decreases, the opening area is zero, but the amount of overlap (normal polymerization amount, overlap value) at the variable orifice 24 formed by the pressure compensating spool 21 and the casing 10 at the spool stroke increases. In addition, since the unloading oil passage is closed by the operation of the main spool 11 in order to carry out the on-load from the unload state, the operating oil flowing from the P port oil chamber 31 is A in the main spool 11. It is switched to the port oil chamber 33 or the B port oil chamber 34. At this time, since the variable orifice 24 is closed or the minimum opening area corresponding to the amount of oil is opened, the stroke of the pressure compensating spool 21 to the operating state is small, and the hydraulic motor 300 operates smoothly. Can be controlled without delay. $
Furthermore, when switching the hydraulic oil with the main spool 11,
In the transient state, it is remarkable that the oil amount increases due to the switching shock phenomenon due to the pressure increase, but in the present embodiment, the variable orifice 24 is in the minimum open state, or is the position close to the zero polymerization state. Therefore, the hydraulic oil in the P port oil chamber 31 whose pressure has increased is the variable orifice 24.
Since it escapes to the T port oil chamber 32 more smoothly, the hydraulic motor 300 can be started up smoothly with almost no increase in pressure. In addition, since the oil passage for unloading is formed by the main spool 11 in the switching state from the operating state of the hydraulic motor 300 to the unloading state, the block state does not occur in the hydraulic circuit and the unloading state does not occur. Since it shifts to, smooth stop can be done without switching shock. $ As explained above, the hydraulic motor 3
00 Pressure compensating spool 2 when unloading when stopped
By adjusting No. 1 so that the oil passage is slightly opened, the pressure compensation state is immediately obtained when the main spool 11 is operated to drive the hydraulic motor 300. There is no jumping phenomenon of the hydraulic motor 300 due to a time delay from the closed state to the open state of the spool 21 or the hydraulic circuit shock phenomenon, and the actuators such as the hydraulic motor 300 can be started more smoothly than in the stopped state. Is. $ Further, by unloading the casing 10 of the flow rate control switching valve 1 and the oil passage of the main spool 11 and opening the switching casing by the pressure compensating spool 21, the P port oil chamber 31 to the T port oil chamber 32 is opened. Since the unload works together, the pressure loss can be reduced as shown in FIG. $ In the series circuit using the flow rate control switching valve having the unloading function, since a large number of hydraulic motors 300 are operated by one hydraulic pump 201, pressure loss during unloading even when the hydraulic motors 300 are stopped. Is a multiple of the number of hydraulic motors 300 (or the number of flow rate adjustment switching valves), resulting in a power loss. Therefore, reducing the pressure loss is effective because the power loss can be reduced. Further, reducing the pressure loss when the series circuit is unloaded can effectively utilize the reduced pressure as an increase in the effective pressure when the hydraulic motor 300 is driven, so that the efficiency can be easily increased by using the same machine. Become. The position of the main spool 11 shown in FIG. 2 is in the neutral state, that is, the unloading state, and the main spool 11 moves from the P port oil chamber 31 to the A port oil chamber 33 or the B port oil chamber 3 with respect to the vertical movement.
4 and the oil passage state from the P port oil chamber 31 to the T port oil chamber 32 will be described with reference to FIG. $ In this neutral state, from the P port oil chamber 31 to the A port oil chamber 33
Alternatively, since the oil passage to the B port oil chamber 34 is closed and there is no flow of hydraulic oil, the hydraulic motor 300 is in a stopped state. An oil passage formed by the main spool 11 and the casing 10 is opened from the P port oil chamber 32, and most of the pump discharge amount is unloaded into the T port oil chamber 32 through this oil passage. If the main spool 11 is operated to move downward, this oil passage is gradually closed in the main spool oil passage 113 and follows the line GB shown in FIG. 8 and is closed at the movement amount "2". The position of this movement amount “2” is the point where the main spool oil passage 114 starts to open from the P port oil chamber 31 to the A port oil chamber 33, and thereafter the main spool oil passage 114 is proportional to the movement amount of the main spool 11. Increase the area. Since this flow rate adjustment switching valve 1 has a pressure compensation function, the amount of oil flowing out from the P port oil chamber 31 to the A port oil chamber 33 increases or decreases according to the area of the main spool oil passage 114. $ This oil passage area and the amount of spilled oil are
This is represented by the line GA in FIG. In the section from the moving amount “2” to “8”, the pressure compensating function is in the on-road state, and the hydraulic oil flowing out from the hydraulic pump 201 has an oil amount corresponding to the moving amount of the main spool 11. It flows into the A port oil chamber 33, and the rest flows from the variable orifice 24 into the T port oil chamber 32 by the pressure compensation spool 21. $
The amount of outflow from the variable orifice 24 to the T port oil chamber 32 is represented by GC in FIG. The variable orifice 24 is slightly opened even in the neutral state so that the main spool oil passages 110, 11 are formed in the main spool 11.
3 and the spring 22 are set, the section of the moving amount "-2" to "2" is also set to P on the main spool 11 which is the neutral area.
The hydraulic oil flows out from the port oil chamber 31 to the T port oil chamber 32. $ From the unloading of the main spool 11 to the outflow of the pressure compensation spool 21 at the boundary of the movement amount "2" of the main spool 11, but from the time of unloading,
Since the hydraulic oil flows out through the variable orifice 24 of the pressure compensating spool 21, it is possible to smoothly shift to the pressure compensating state, so that the hydraulic motor 300 can be smoothly started without shock due to pressure fluctuation. Next, FIG. 9 is a graph showing characteristics of the conventional device in a transfer state according to the conventional structure for such smooth startup of the hydraulic motor 300 of the present embodiment.
Will be described with reference to. Since the outflow timing with respect to the movement amount of the main spool 11 is the same, the oil passage from the P port oil chamber 31 to the T port oil chamber 32 is blocked at the movement amount “2”, and unloading is eliminated. After that, the oil passage gradually opens from the P port oil chamber 31 to the A port oil chamber 33, but at the movement amount "2", the oil passage from the P port oil passage 31 to the T port oil passage 32 is blocked, and the P port oil passage is closed. The oil passage from the oil passage 31 to the A port oil passage 33 is not opened, and a block state occurs on the hydraulic circuit. In this case, the pressure compensating spool 21 tries to push up the pressure compensating spool 21 via the pressure compensating spool oil passage 231 by the pressure of the P port oil chamber 31, but the spring oil chamber 211 of the pressure compensating spool 21 is closed. Therefore, the pilot relief valve 211a installed in the upper part of the spring operates to release the oil in the spring oil chamber 211 to a low pressure.
Only a slight compression of 11 goes up. The pressure in the P port oil chamber 31 rises until the variable orifice 24 opens. This pressure rises again when the relief valve is set on the hydraulic pump side 201, and rises to the set pressure of the pilot relief valve 211a when it is not set. If neither the relief valve (not shown) of the hydraulic pump 201 nor the pilot relief valve 221a is present, the hydraulic pump 201 may further rise and a part of the device may be damaged. $ If the main spool 11 is further moved from the state where the pressure is increased, the oil passage is opened from the P port oil chamber 31 to the A port oil chamber 33, but the hydraulic pressure is increased when the pressure of the P port oil chamber 31 is increased. Since the motor 300 is driven, it suddenly starts moving regardless of the load of the hydraulic motor 300. Further, until the variable orifice 24 is opened, the oil passage from the P port oil chamber 31 is only the main spool oil passage 114, so that the entire amount of the hydraulic oil flowing into the P port oil chamber 31 is the A port oil chamber 33. To the hydraulic motor 300, which is dangerous. If working oil flows too much into the main spool oil passage 114, a large pressure difference is generated between the P port oil chamber 31 and the A port oil passage 33.
The pressure compensating spool 21 opens the variable orifice 24 to allow the working oil in the P port oil chamber 31 to escape to the T port oil chamber 32, reduce the working oil flowing to the A port oil chamber 33, and to perform pressure compensation to perform normal operation. . As a measure against this, the main spool 11 is used to connect the P port oil chamber 31 to the T port oil chamber 3
If the oil passage to 2 is opened after the oil passage from the P port oil chamber 31 to the A port oil chamber 33 is opened (see the line GD in FIG. 9), the hydraulic oil is blocked in a circuit manner. However, the hydraulic motor 300 can be started smoothly, but the neutral range becomes wider and the flow rate control range becomes narrower (moving amount “2” to “8” → moving amount “3” to “8”). There is a drawback that. Further, between the movement amount “2” and “3”, P, T,
Since the port oil chambers 31, 32, 33, and 34 of A and B are connected to each other, there is a disadvantage that the hydraulic motor 300 cannot be used when there is a load. In the present embodiment, the above-mentioned conventional defects can be eliminated. $

As described above, according to the present invention, the control hydraulic passage is formed between the casing of the directional control valve and the main spool of the directional control valve in the neutral state so that the supply side port and the discharge side port communicate with each other. By doing so, the hydraulic oil is unloaded, and the adjustment hydraulic passage that connects the upstream hydraulic chamber and the downstream hydraulic chamber of the pressure compensating valve is opened with a smaller opening than the total opening. The pressure loss at the time of unloading the formed oil passage can be reduced as much as possible, and smooth and stable hydraulic control can be performed. Further, since the control hydraulic passage at the time of unloading is formed between the casing of the directional control valve and the main spool, there is an effect that the entire device can be downsized. Further, in the present invention, when the pressure compensating valve communicates the upstream side hydraulic chamber and the downstream side hydraulic chamber, the set pressure of the spring of the pressure compensating valve is set to the magnitude of the pressure loss of the passage hydraulic passage of the main spool of the directional control valve. Since it is set to be smaller than this, there is an effect that the hydraulic control at the time of unloading can be further smoothed.

[Brief description of drawings]

FIG. 1 is a schematic hydraulic circuit diagram of a hydraulic control valve according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a neutral operating state of a hydraulic control valve according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a neutral operating state of a hydraulic control valve according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a neutral operating state of a hydraulic control valve according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating an operating state of the hydraulic control valve according to the embodiment of the present invention.

FIG. 6 is a pressure loss characteristic diagram of a hydraulic control valve according to an embodiment of the present invention.

FIG. 7 is a characteristic diagram of a variable orifice oil amount in the pressure compensation valve of the hydraulic control valve according to the embodiment of the present invention.

FIG. 8 is a flow rate characteristic diagram of a hydraulic control valve according to an embodiment of the present invention.

FIG. 9 is a flow rate characteristic diagram of a conventional hydraulic control valve.

FIG. 10 is a schematic hydraulic circuit diagram of a conventional hydraulic control valve.

FIG. 11 is a sectional view for explaining an operating state of a conventional hydraulic control valve.

[Explanation of symbols]

 1 flow rate adjustment switching valve 1a reverse rotation switching valve 1b forward rotation switching valve 2 pressure compensation valve 10 casing 11 main spool 12 operation lever 21 pressure compensation spool 22 spring 23 pressure compensation spool orifice 24 variable orifice 31 P port oil chamber 32 T port oil chamber 31a / 31b, 32a / 32b Step 33 A port oil chamber 34 B port oil chamber 101 Casing orifice 25, 102, 103, 106 Casing oil passage 111, 112, 113, 114 Main spool oil passage 201 Hydraulic pump 202 High pressure line 203 Return line 204 Drain line 211 Spring-side oil chamber 212 Anti-spring-side oil chamber 300 Hydraulic motors 301, 302 Motor line

Claims (2)

[Claims] 1. A hydraulic oil from an upstream port is output to a downstream side via any one of a plurality of switching ports, and is input from a load side via any one of the plurality of switching ports, A directional control valve that switches the flow direction of the hydraulic oil in the plurality of switching ports by moving the main spool, an upstream hydraulic chamber connected to the supply port and a discharge side port, and a predetermined pressure is applied by a spring force. In a hydraulic control device provided with a pressure compensating valve that adjusts the hydraulic fluid flowing through the directional control valve to a substantially constant value according to an equilibrium condition with an additional spring-side hydraulic chamber, stopping the outflow of hydraulic fluid to the load side. A control hydraulic passage that is formed by the casing of the directional control valve and the main spool at the time of neutralization, and that communicates the supply side port and the discharge side port to unload the working oil; Hydraulic control apparatus characterized by comprising a regulating hydraulic passage opening smaller than the upstream-side hydraulic chamber and the downstream side hydraulic chamber and the Zenrendori opening of the pressure compensating valve in. 2. The hydraulic control device according to claim 1, wherein the pressure compensating valve adjusts a set pressure of a spring of the main spool of the directional control valve when the upstream side hydraulic chamber and the downstream side hydraulic chamber are communicated with each other. A hydraulic control device characterized in that it is set to be smaller than the magnitude of pressure loss in a passing hydraulic passage.