JPH0636321Y2 - Signal extraction circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic circuit for extracting a signal from a pilot pump according to the operation of a plurality of center bypass type multiple control valves.

[Prior Art] Conventionally, in a hydraulic circuit that drives actuators via center bypass type multiple control valves respectively connected to a plurality of main pumps, all the switching valves included in the multiple control valves are neutral. A signal extraction circuit is provided to determine if the condition or at least one switching valve is in the actuated position. As a specific means, when the switching valve is operated manually, a limit switch that mechanically detects the movement of the operating lever or spool of each switching valve is attached to take out an electrical signal, or a selector valve is attached to each switching valve. The hydraulic signal was taken out by connecting. When the switching valve operates pilot pressure, the pilot pressures on both sides that operate each switching valve are connected by a shuttle valve to determine which is higher, and the pilot pressure between these switching valves is determined by the shuttle valve. It was constructed by successively superimposing shuttle valves so that the higher pressure can be judged by connecting with, and the maximum pressure was picked up from the operating pilot pressures of all the switching valves and taken out as an output signal.

[Problems to be Solved by the Invention] However, in order to extract the signal for switching valve operation as described above, when the number of switching valves in a plurality of multiple control valves increases, in the case of a manually operated switching valve, Requires the same number or twice as many detectors as the switching valve, and the total number of switching valves is n in the case of switching valves that operate pilot pressure.
If all of them are multiple types, 2n-1 shuttle valves and piping for connecting them are required, and in any case, there is a drawback that a large amount of cost and a vast occupied space are required. there were.

An object of the present invention is to improve this point, and in a hydraulic circuit in which a center bypass type multiple control valve is connected to each of a plurality of main pumps, at least one of the multiple control valves is included in the hydraulic circuit. The output signal when two switching valves are operated can correspond to either manual operation or pilot pressure operation of the switching valve, reducing cost and occupying space as compared with the conventional one, and multiple control valve It is an object of the present invention to provide a signal extraction circuit in which the merits become greater as the number of switching valves included in (1) increases.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a center bypass type multiple control valve connected to each of a plurality of main pumps, and each of the multiple control valves is provided with a center bypass type multiple control valve. In a hydraulic circuit configured to drive each actuator connected to each switching valve provided and to communicate the downstream of the multiple control valve to the tank, the hydraulic circuit is arranged in parallel with each of the main pumps. From the pilot pump by connecting the pilot oil passages branched from upstream and downstream of the series control valve to the pilot pressure chamber to oppose each other and interposing an opening / closing valve that operates by the pressure difference between the upstream and downstream of the multiple control valve. A signal outlet that is configured to connect and block the pressure oil from the signal outlet to the signal outlet, and branch from the passage to the signal outlet and connect to the tank via a throttle. The circuit.

Further, in the hydraulic circuit configured to communicate with the tank by interposing a pressure generating member downstream of the multiple control valve, from the upstream side and the downstream pressure generating member inlet side of the multiple control valve, respectively. The branched pilot oil passage is connected to the pilot pressure chamber so as to be opposed to each other, and the on-off valve operated by the pressure difference between the upstream and downstream of the multiple control valve is interposed to communicate the pressure oil from the pilot pump to the signal outlet. • A signal extraction circuit configured to shut off.

[Operation] In the signal extraction circuit configured as described above, first, when all of the switching valves of the multiple control valves are set to the neutral position, the main pumps directly communicate with the tank via the center bypass passages of the switching valves. Will be unloaded, so
There is no pressure difference between the pressure oil on the upper and downstream sides of the center bypass passage that acts on the pilot pressure chambers on both sides of the on-off valve via the pilot oil passages branched from the upstream and downstream of the multiple control valve, respectively. Is operated to the closed position to close the valve passage, and the pressure oil from the pilot pump to the signal outlet is shut off. At this time, the pressure at the signal outlet is the lowest value because it is connected to the tank through the throttle. Next, when at least one of the switching valves is switched, the center bypass passage is cut off, and the pressure of the main pump reaches a load pressure for driving an actuator (not shown) connected to the switching valve. Therefore, the on-off valve arranged in parallel to the main pump acts on one pilot pressure chamber via the pilot oil passage branched from the upstream of the center bypass passage of the multiple control valve including the switching valve. There is a pressure difference between the pressure of the main pump and the pressure acting on the other pilot pressure chamber via the pilot oil passage branched from the downstream of the center bypass passage that is communicated with the tank and cut off by the switching of the switching valve. As a result, the on-off valve operates in the open position and opens the valve passage, so that the pressure oil from the pilot pump is returned to the tank through the on-off valve and the throttle, and the signal outlet is throttled. A loss pressure is applied as it passes. In this way, the pressure oil from the pilot pump is taken out as a pressure signal to the signal outlet in accordance with the operation of switching at least one of the switching valves included in the plurality of center bypass type multiple control valves. Become. Further, also in a hydraulic circuit configured to communicate with a tank by interposing a pressure generating member downstream of the multiple control valve, similarly, from the upstream side and the downstream pressure generating member inlet side of the multiple control valve, respectively. The branched pilot pressure oil is made to oppose and act on the pilot pressure chamber to operate the opening / closing valve by the pressure difference between the upstream and downstream of the multiple control valve, and the pressure oil from the pilot pump is taken out through this opening / closing valve. Will be taken out as a pressure signal.

[Embodiment] A first embodiment of the present invention will be described below with reference to FIG. In the figure, center bypass type multiple control valves 21 and 22 respectively connected to a plurality of main pumps 1 and 2 are provided, and one multiple control valve 21 has switching valves 3 and 4 and the other multiple control valve 21. The switching valves 5 and 6 are installed in the continuous control valve 22, and these switching valves
Not shown actuators are connected to 3, 4, 5 and 6 to drive them, and a hydraulic circuit that connects the center bypass passages of the multiple control valves 21 and 22 to the tank 20 is configured.

Therefore, in the present invention, the pilot oil passages 11 and 12 respectively branched from the upstream of the multiple control valves 21 and 22 connected to the main pumps 1 and 2 and the downstream from the multiple control valves 21 and 22 respectively are branched. The on-off valve 13 and the on-off valve 14 which operate by connecting the pilot oil passages 12 and 10 to the pilot pressure chamber and operating by opposing the upstream and downstream pressures of the center bypass passages of the multiple control valves 21 and 22 respectively. It is arranged in parallel with the main pumps 1 and 2, and by interposing the opening / closing valve 13 and the opening / closing valve 14, the pressure oil of the pilot pump 15 is formed to communicate with or cut off from the signal outlet 16. . Further, it branches from the passage to the signal output port 16 and is connected to the tank 20 via the throttle 18.

Explaining the operation of the circuit configured as described above, first, when all of the switching valves 3 and 4 and the switching valves 5 and 6 of the multiple control valves 21 and 22 are set to the neutral position, the main pumps 1 and 2 are
Are unloaded by communicating directly with the tank 20 through the center bypass passages of the switching valves 3 and 4 and the switching valves 5 and 6, respectively, so that the pilot oil branched from the upstream and downstream of the multiple control valves 21 and 22 respectively. There is no pressure difference in the pressure oil on the upstream and downstream sides of the center bypass passage that acts on the pilot pressure chambers on both sides of the on-off valves 13, 14 via the passages 11, 9 and 12, 10, and the on-off valves 13, 14 are By the force of a return spring attached to the pilot pressure chamber, the valve passage is closed by operating to the closed position, and the pressure oil from the pilot pump 15 to the signal outlet 16 is shut off. At this time, the pressure at the signal outlet 16 is reduced.
It is connected to the tank 20 via 18 and has the lowest value. Next, when at least one switching valve among the switching valves 3 and 4 and the switching valves 5 and 6, for example, the switching valve 3, is switched, the center bypass passage is cut off and the pressure of the main pump 1 is transferred to the switching valve 3. The load pressure of the connected actuator (not shown) is reached. Therefore, the on-off valve 13 arranged in parallel to the main pump 1 is provided with one pilot pressure via the pilot oil passage 11 branched from the upstream of the center bypass passage of the multiple control valve 21 to which the switching valve 3 belongs. The pressure of the main pump 1 acting on the chamber and the pressure acting on the other pilot pressure chamber via the pilot oil passage 9 branched from the downstream of the center bypass passage which is communicated with the tank 20 and cut off by the switching of the switching valve 3. As a result, a pressure difference is generated, and as a result, the on-off valve 13 operates in the open position to open the valve passage, so that the pressure oil discharged from the pilot pump 15 is returned to the tank via the on-off valve 13 and the throttle 18. At the same time, squeeze the signal outlet 16
The loss pressure as it passes through 18 is applied. in this way,
A pressure signal can be taken out from the pilot pump 15 to the signal take-out port 16 via the opening / closing valve 13 according to the operation of switching one of the switching valves 3 and 4 of the multiple control valve 21.
Even when the switching valve 5 or 6 included in the other multiple control valve 22 is switched, a pressure signal can be similarly taken out from the pilot pump 15 to the signal taking-out port 16 via the opening / closing valve 14.

FIG. 2 shows a second embodiment of the present invention which is a modification of the first embodiment shown in FIG.
The pressure generating members 7 and 8 are arranged downstream of the center bypass passages 21 and 22, and the others are the same as those in the first embodiment.
This type of pressure generating member is generally widely used to detect a large amount of oil passing through the center bypass passage near the neutral position of the switching valve where it is not necessary to supply pressure oil to the actuator and reduce the discharge amount of the pump. It is used and is composed of a throttle or a throttle valve and a relief valve connected in parallel. In such a hydraulic circuit, as illustrated in FIG. 3, the load pressure change of the main pump with respect to the movement amount of the switching valve,
That is, the upstream pressure C of the multiple control valve has a characteristic that the pressure loss B generated by the passage of the center bypass passage is accumulated on the pressure loss A generated in the pressure generating member, and the movement amount of the switching valve near the neutral position of the switching valve. There is a tendency that the pressure of the main pump rises slowly with respect to, or temporarily decreases during the process. In the second embodiment, the pilot oil passages branched from the upstream side and the downstream side of the pressure generating member inlet side of the multiple control valve are connected to the pilot pressure chambers so as to oppose each other, and the upstream and downstream of the multiple control valve are opposed to each other. Just before the center bypass passage in
Since the on-off valve is operated by the pressure difference due to the main pump generated immediately after, the pressure oil from the pilot pump is used as a pressure signal to the signal outlet via this on-off valve in the same manner as described in the first embodiment. Can be taken out.

[Advantage of the Invention] As described above, according to the present invention, the pilot oil passages are branched from upstream and downstream of the multiple control valves respectively connected to the main pumps, and connected to the pilot pressure chambers to perform multiple control. On-off valves that operate by opposing the upstream and downstream pressures of the center bypass passage of the valve are arranged in parallel with the main pump, and by interposing these on-off valves, the pressure oil of the pilot pump is taken out as a signal outlet. When at least one switching valve is switched, the center bypass passage is blocked, and the on-off valve arranged in parallel to the main pump has its multiple control The pressure of the main pump that acts on one pilot pressure chamber via the pilot oil passage branched from the upstream and downstream of the center bypass passage of the valve and communicates with the tank and switches the switching valve A pressure difference is generated between the pressure acting on the other pilot pressure chamber via the pilot oil passage branched from the downstream of the center bypass passage blocked by the valve, and as a result, the on-off valve operates in the open position. Since the valve passage is opened, pressure oil from the pilot pump is sent to the signal outlet via the on-off valve in response to the operation of switching at least one of the switching valves of the multiple center bypass type multiple control valves. It is taken out as a pressure signal. Therefore, it becomes unnecessary to construct a large number of mechanical detection units required for a manually operated switching valve and a large number of shuttle valves required for a pilot pressure operated switching valve as in the conventional case. It is possible to reduce a large amount of cost and a large occupied space as compared with the conventional one, and moreover, there is an effect that these advantages become larger as the number of switching valves in the multiple control valve increases.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention, and FIG.
FIG. 3 is a hydraulic circuit diagram showing a second embodiment of the present invention, and FIG. 3 is a diagram for explaining the relationship between the moving amount of the switching valve and the generated pressure in the second embodiment of the present invention. 1,2 ...... Main pump, 3 to 6 ...... Switching valve, 7,8 ...... Pressure generating member, 9 to 12 ...... Pilot oil passage, 13,14 ...... Open / close valve, 1
5 …… Pilot pump, 16 …… Signal outlet, 18 ……
Throttle, 21, 22 ... Multiple control valve.

Claims (2)

[Scope of utility model registration request] 1. A center bypass type multiple control valve connected to each of a plurality of main pumps is provided to drive each actuator connected to each switching valve provided in each of the multiple control valves. In a hydraulic circuit configured to communicate the downstream of the multiple control valve to a tank, pilot oil passages that are respectively arranged in parallel to the main pump and branched from upstream and downstream of the multiple control valve are provided. The pressure oil from the pilot pump is communicated with and cut off from the signal outlet by interposing an opening / closing valve that is connected to the pilot pressure chamber to oppose it and operate by the pressure difference between the upstream and downstream of the multiple control valve. A signal extraction circuit characterized in that it is configured to branch from a passage to an extraction port and be connected to a tank through a throttle. 2. A center bypass type multiple control valve connected to each of a plurality of main pumps is provided to drive each actuator connected to each switching valve disposed in each of the multiple control valves, and In a hydraulic circuit configured to communicate with a tank by interposing a pressure generating member downstream of the multiple control valve, the hydraulic circuit is arranged in parallel to the main pump, and the upstream and the downstream of the multiple control valve are arranged. The pilot oil passages branched from the inlet side of the pressure generating member are connected to the pilot pressure chamber to oppose each other, and an on-off valve operated by the pressure difference between the upstream and downstream of the multiple control valve is interposed so that the pilot pump Communication of pressure oil to signal outlet
A signal take-out circuit, which is configured to be cut off and branched from a passage to the signal take-out port and connected to a tank via a throttle.