JPH112202A - Solenoid valve hydraulic control circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy saving type circuit to maintain a pilot pressure without keeping an unload valve in an exciting state. SOLUTION: A selector valve 32 to intercommunicated the unload valve 27 and a pump P and disconnect the communication therebetween is arranged upper stream from the unload valve 27, and a pressure in a feed passage 7 is guided to the pilot chamber 33 of the selector valve 32 through a pilot passage 34. When, simultaneously with operation of switch means 23-26, the unload valve 27 is switched and communication between the pump P and a tank T is disconnected, a pilot pressure is generated at a main pilot passage 31. Meanwhile, when a prescribed pressure is generated in a spot situated upper stream from the unload valve 27, a sequence valve 6 is opened, the selector valve 32 is switched by a pressure generated at the feed passage 7, the selector valve 32 is switched, and communication between the pump P and the unload valve 27 is disconnected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic valve hydraulic control circuit for generating an operating pressure for an actuator and a pilot pressure for switching a control valve with a single pump.

[0002]

2. Description of the Related Art In a conventional solenoid valve hydraulic control circuit shown in FIG. 4, a sequence valve 6 is connected to a pump P via a pump passage 5. The sequence valve 6 opens when a predetermined pressure is generated in the pump passage 5, and connects the pump passage 5 to a supply passage 7 connected downstream of the sequence valve. A parallel feeder 8 and a neutral passage 9 are connected to the supply passage 7. The parallel feeder 8 is connected to a plurality of control valves 1 to 4 which are parallel to each other. The neutral passage 9 is connected to the tank T via the plurality of control valves 1-4, and connects the supply passage 7 to the tank T when all of the control valves 1-4 are neutral.

The control valves 1 to 4 have inlet ports 10 to 13 connected to a parallel feeder 8 and tank passages 14.
And reflux ports 15 to 18 connected thereto. These control valves 1-4 are switched by introducing pilot pressure controlled by solenoids 23-26 to pilot chambers 19-22. Then, when the control valve is switched, the port communicates with an actuator (not shown).

On the other hand, the pump passage 5 and the tank passage 14
Is connected to the first branch passage 5a.
Are connected. The unload valve 27 normally maintains the normal position shown in the figure, but switches when the solenoid 30 is excited to cut off the communication between the pump passage 5 and the tank passage 14. The solenoid 30 has control valves 1-4.
When the solenoids 23 to 26 provided in the above are excited, they are simultaneously excited.

The pump passage 5 is connected to a second branch passage 5b. A pressure reducing valve 28 is connected to the second branch passage 5b. Downstream of the pressure reducing valve 28, the pilot chambers 19 to 2 are connected via a main pilot passage 31.
3 are connected. Reference numeral 29 denotes a relief valve. When the pressure in the pump passage 5 becomes equal to or higher than the set pressure, the relief valve 29 is connected to the pump passage 5 and the tank passage 14.
And communicate with. Then, the pressure in the circuit is suppressed within the set pressure by discharging the pressure in the pump passage 5 to the tank T.

Next, the operation of this conventional example will be described. FIG.
When all the control valves 1 to 4 are in the neutral position, the solenoid 30 of the unload valve 27 also keeps the demagnetized state as shown in FIG.
Through the tank T. In this case, since the tank pressure is on the upstream side of the sequence valve 6, no pilot pressure is generated in the main pilot passage 31.

When any one of the solenoids 23 to 26 of the control valves 1 to 4 is excited from the above state, the unload valve 27
Is also excited at the same time. Therefore, the unload valve 27 is switched to the upper position in the figure, and the communication between the pump passage 5 and the tank passage 14 is cut off. When the communication between the pump passage 5 and the tank T is interrupted, pressure is generated in the pump passage 5. The pressure in the pump passage 5 is determined by the set pressure of the sequence valve 6, and this pressure becomes the main pilot pressure. Then, this pressure is guided to the main pilot passage 31 via the pressure reducing valve 28. The main pilot pressure guided to the main pilot passage 31 is controlled by a predetermined solenoid and guided to each pilot chamber. Then, the control valve is switched by the pressure led to the pilot chamber.

On the other hand, when the pressure in the pump passage 5 becomes equal to or higher than the set pressure of the sequence valve 6, the sequence valve 6
Opens to connect the pump passage 5 and the supply passage 7. Therefore, the discharge oil of the pump P is supplied to the parallel feeder 8 via the supply passage 7. The discharge oil of the pump P supplied to the parallel feeder 8 is supplied to an actuator (not shown) via the switched control valve.

[0009]

In the conventional solenoid valve hydraulic control circuit, the solenoid 30 of the unload valve 27 must be always kept in an excited state in order to maintain the pilot pressure for switching the control valves 1-4. Did not. Therefore,
That much power was required. The purpose of this invention is
An object of the present invention is to provide a solenoid valve hydraulic control circuit that operates with low power consumption.

[0010]

According to a first aspect of the present invention, there is provided a pump, a sequence valve connected to the pump and opened when the pressure on the primary side reaches a predetermined pressure, and a supply valve connected downstream of the sequence valve. A passage, a plurality of control valves connected to the supply passage and parallel to each other, and a neutral passage connected to the supply passage and communicating the sequence valve and the tank when the plurality of control valves are all neutral. A switching valve connected to the pump and parallel to the sequence valve, an unload valve connected downstream of the switching valve, a tank passage connected downstream of the unload valve and communicating with the tank, A pilot passage for guiding the pressure in the supply passage to the pilot chamber of the switching valve; A reducing valve in parallel to have, it includes a main pilot passage connected to the pressure reducing valve, and a switching means for switching the main pilot passage led was to control the pilot pressure of the plurality of control valves.

When the communication between the pump and the tank passage is interrupted by switching the unload valve at the same time as the operation of the switching means, a predetermined pilot pressure is generated in the main pilot passage, while the upstream side of the unload valve is provided. When the pressure reaches a predetermined pressure, the sequence valve opens, the pump communicates with the supply passage, and the pressure generated in this supply passage is
The switching valve is guided to the pilot chamber and is switched to disconnect the communication between the pump and the unload valve.

According to a second aspect of the present invention, there is provided a pump, a flow dividing type throttle switching valve connected to the pump and controlling a flow rate to the first and second ports according to a switching position, the first port and the tank. A relief valve connected between the relief valve and the first port. The relief valve is connected between the relief valve and the first port at a normal position to cut off communication between the relief valve and the first port. An unload valve for communicating with the port, a discharge passage for discharging pressure between the unload valve and the relief valve to the tank via the unload valve at the normal position, and a discharge passage between the first port and the relief valve. A throttle provided therebetween, a first pilot passage for guiding pressure upstream of the throttle to one pilot chamber of the throttle switching valve, and a pressure guide downstream of the throttle for the other pilot chamber of the throttle switching valve. When the second pilot passage, and a plurality of control valves that in parallel with one another as well as connected to the second port, all of which control valve is in the neutral position,
A neutral passage connecting the second port to the tank, a pressure reducing valve connected to the pump and parallel to the throttle switching valve, a main pilot passage connected to the pressure reducing valve, and a pilot pressure guided to the main pilot passage. And switching means for switching the control valve by controlling the control valve.

When the unloading valve is switched at the same time as the operation of the switching means, the communication between the pump and the second port is cut off by the throttle switching valve, while the fluid guided from the pressure reducing valve to the main pilot passage is opened. When the pressure reaches a predetermined pressure, the unload valve returns to the normal position,
The throttle switching valve is switched to connect the second port to the pump.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment shown in FIG. 1, a switching valve 3 is provided in a first branch passage 5a upstream of an unload valve 27.
2 is connected to a pilot chamber 33 of the switching valve 32, which is connected to a pilot passage 34 that guides the pressure in the supply passage 7. This point is different from the conventional example, and the other configuration is the same as the conventional example. Therefore, in the first embodiment, only differences from the conventional example will be described, and detailed description of the same configuration as the conventional example will be omitted.

As shown in FIG. 1, a switching valve 32 is connected to the first branch passage 5a upstream of the unload valve 27.
A pilot passage 34 that guides the pressure in the supply passage 7 is connected to the pilot chamber 33 of the switching valve 32. Therefore, when a predetermined pressure is generated in the supply passage 7, the switching valve 3
2 is switched, and the communication between the pump passage 5 and the unload valve 27 is cut off.

Next, the operation of the first embodiment will be described.
When one of the solenoids 23 to 26 is excited to excite the solenoid 30 and switch the unload valve 27, a pressure is generated in the pump passage 5 and a predetermined main pilot pressure is supplied to the main pilot passage 31. When the pressure in the pump passage 5 increases, the sequence valve 6 opens, and the pump passage 5 and the supply passage 7 communicate with each other.
Therefore, the discharge oil of the pump P is guided from the supply passage 7 to the parallel feeder 8, and is supplied to an actuator (not shown) via a predetermined control valve.

On the other hand, the pressure in the supply passage 7 is guided to the pilot chamber 33 of the switching valve 32 via the pilot passage 34. Therefore, the switching valve 32 is switched to the upper position in the figure, and the communication between the pump passage 5 and the unload valve 27 is cut off. Thus, the pump passage 5 and the unload valve 2
If the communication with the tank 7 is cut off, the pump P and the tank T will not communicate with each other even if the unload valve 27 is returned to the normal position. That is, the pilot pressure can be maintained. Therefore, after the switching valve 32 is switched, the unload valve 27
If the energization of the solenoid 30 is stopped, the power consumption can be reduced accordingly.

The second embodiment shown in FIGS.
And the control valves 1 to 4
Is different from the conventional example in that the pilot pressure is introduced into the pilot chambers 19 to 22, but the configuration of the control valves 1 to 4 is the same as the conventional example. Thus, in the second embodiment, a configuration different from the conventional example will be described, and a detailed description of the same configuration as the conventional example will be omitted. Control valves 1-4
Pilot chambers 19 to 22 and solenoids 23
26 are switching means of the present invention.

As shown in FIG. 2, the pump P is connected to a flow dividing type throttle switching valve 40. The throttle switching valve 40 controls the supply amount to the first port 41 and the second port 42 according to the switching position. The supply passage 7 is connected to the second port 42 of the throttle switching valve 40, and the parallel feeder 8 and the neutral passage 9 are connected to the supply passage 7. The control valves 1 to 4 are connected to the parallel feeder 8 as in the conventional example, and the neutral passage 9 is connected to the tank T and the supply passage 7 when all of the control valves 1 to 4 are at the neutral position. To communicate.

On the other hand, the first port 4 of the throttle switching valve 40
1 is connected to an unload valve 44 via a first passage 43. A first relief valve 47 corresponding to a relief valve of the present invention is connected to a port 45 of the unload valve 44 via a second passage 46. When the pressure on the upstream side reaches the set pressure, the first relief valve 47 communicates the second passage 46 with the tank passage 14.

The unload valve 44 normally keeps the normal position shown in the figure, and cuts off the communication between the first passage 43 and the second passage 46. The unload valve 44 communicates the second passage 46 and the discharge passage 48 at the normal position. Further, when the unload valve 44 is switched by the excitation of the solenoid 49, the unload valve 44 connects the first passage 43 and the second passage 46. The solenoid 49
Excites and simultaneously excites the solenoids 23 to 26 provided in the control valves 1 to 4.

A throttle 50 is provided in the first passage 43. Then, the pressure on the upstream side of the throttle 50 is guided to one pilot chamber 40 a of the throttle switching valve 40 via the first pilot passage 51. The second pilot passage 5 is provided in the other pilot chamber 40 b of the throttle switching valve 40.
2, the pressure in the second passage 46 is conducted.

On the other hand, on the upstream side of the throttle switching valve 40,
The branch passage 53 is connected. In this branch passage 53,
The pressure reducing valve 54 is connected, and the main pilot passage 31 is connected downstream thereof. This main pilot passage 31
Is the pilot chamber 19 of the control valves 1-4 as in the prior art.
~ 22. The pilot chambers 19 to 22 are provided with solenoids 23 to 26 for controlling the opening degree of communication with the main pilot passage 31. The maximum pressure on the secondary side of the pressure reducing valve 54 is set to be substantially the same as the set pressure of the first relief valve 47.
Reference numeral 55 denotes a second relief valve, and its set pressure is set higher than the set pressure of the first relief valve 47.

Next, the operation of the second embodiment will be described.
When all of the control valves 1 to 4 are at the neutral position, the unload valve 44 maintains the normal position and cuts off the communication between the first port 41 and the first relief valve 47. Therefore, the first passage 4
In 3, a pressure is generated by the discharge pressure of the pump P. This pressure is supplied to the throttle switching valve 4 via the first pilot passage 51.
The pilot room 40a is guided to the pilot room 40a. The pilot pressure thus guided acts on one end 56a of the spool 56 of the throttle switching valve 40, as shown in FIG. Therefore, the spool 56 moves rightward in the figure while resisting the elastic force of the spring 57 provided in the pilot chamber 40b. The first port 41 is closed by the movement of the spool 56, and the second port 42 communicates with the pump P. Therefore, the entire discharge oil of the pump P is supplied to the second port 4
2 to the supply passage 7.

When any one of the solenoids 23 to 26 is excited from the above state, the solenoid 49 provided on the unload valve 44 is also excited. When the solenoid 49 is excited, the spool 59 of the unload valve 44 is pushed leftward in the figure by the push rod 58. Therefore, the spool 59 moves leftward in the figure while resisting the elastic force of the spring 60, and connects the first passage 43 and the second passage 46.

When the two passages 43 and 46 communicate with each other, the pressures in the passages 43 and 46 become equal. This equal pressure is guided to the two pilot chambers 40a, 40b of the throttle switching valve 40 via the first and second pilot passages 51, 52. Therefore, the pilot pressures acting on both ends 56a and 56b of the spool 56 of the throttle switching valve 40 cancel each other out, and the spool 56 makes a full stroke leftward in the drawing by the elastic force of the spring 57. When the spool 56 of the throttle switching valve 40 makes a full stroke to the left, the pump P and the first port 41 communicate with each other, and the communication of the second port 42 with the pump P is cut off.

When the communication between the pump P and the second port 42 is cut off, a pressure determined by the set pressure of the first relief valve 47 is generated in the first and second passages 43 and 46. The generated pressure is guided to the pressure reducing valve 54 via the branch passage 53, and from the pressure reducing valve 54 to the main pilot passage 31 as a main pilot pressure. The main pilot pressure guided to the main pilot passage 31 is controlled by the excited solenoid and guided to the pilot chamber. The control valve is switched by the pressure in the pilot chamber. That is, the main pilot pressure guided to the pilot chambers 19 to 22 is generated at the same time when the solenoids 23 to 26 are excited.

On the other hand, when the pressure in the first and second passages 43 and 46 exceeds the set pressure of the first relief valve 47, the first
The relief valve 47 is opened, and the second passage 43 and the tank passage 14 are opened.
Communicates with Therefore, the discharge oil of the pump P is supplied to the throttle switching valve 40 → the first port 41 → the first passage 43 → the throttle 50.
→ Unload valve 44 → Port 45 → Second passage 46 → First
It flows from the relief valve 47 to the tank passage 14 in this order. When the discharge oil flows as described above, a pressure difference is generated between the upstream side and the downstream side of the throttle 50. This pressure difference is transmitted to the two pilot chambers 40a and 40b of the throttle switching valve 40 by the first and second pilot passages 51 and 52. Therefore, the spool 56 of the throttle switching valve 40 moves to a position where the pressure difference generated in the throttle 50 and the elastic force of the spring 57 are balanced, as shown in FIG.

When the spool 56 moves as described above,
The pump P communicates with both the first and second ports 41 and 42. Therefore, the discharge oil of the pump P is supplied from the second port 42 to the parallel feeder 8 via the supply passage 7.
Then, the discharge oil of the pump P supplied to the parallel feeder 8 is supplied to an actuator (not shown) via the switched control valve.

When the discharge oil of the pump P is supplied to the actuator as described above, a pressure is generated in the supply passage 7 connected to the second port 42 due to the load of the actuator.
Further, the first relief valve 47 is provided downstream of the first port 41.
Pressure. Therefore, these first and second
A predetermined main pilot pressure is maintained in the main pilot passage 53 provided on the upstream side of the ports 41 and 42. On the other hand, when the unload valve 44 is switched to the normal position, the communication between the first port 41 and the first relief valve 47 is cut off. In this state, the pilot pressure in the main pilot passage 53 can be maintained. Therefore, it is not necessary to keep the solenoid 49 of the unload valve 44 in the excited state once the control valves 1-4 are switched. Therefore, if the power supply to the solenoid 49 is stopped after the predetermined main pilot pressure is generated in the main pilot passage 31, the power consumption can be reduced accordingly.

[0031]

According to the first and second aspects of the present invention, the pilot pressure for switching the first to fourth control valves can be maintained even if the unload valve is returned to the normal position. for that reason,
In the case where the unload valve is electrically switched by a solenoid or the like, if the unload valve is switched by a solenoid and then the energization of the solenoid is stopped, the power consumption can be reduced accordingly. Therefore, the power consumption of the entire solenoid valve hydraulic control circuit can be reduced.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a first embodiment.

FIG. 2 is a hydraulic circuit diagram of a second embodiment.

FIGS. 3A and 3B are structural diagrams of a second embodiment, in which FIG. 3A is a diagram illustrating a state where an unload valve is not excited, and FIG. 3B is a diagram illustrating a state where the unload valve is excited.

FIG. 4 is a hydraulic circuit diagram of a conventional example.

[Explanation of symbols]

1-4 Control valve 6 Sequence valve 7 Supply passage 9 Neutral passage 14 Tank passage 19-22 Pilot chamber constituting switching means of the present invention 23-26 Pilot chamber constituting switching means of the present invention 27 Unload valve 28 Pressure reducing valve 31 Main Pilot Passage 32 Switching Valve 33 Pilot Chamber 34 Pilot Passage 40 Throttle Switching Valve 41 First Port 42 Second Port 44 Unload Valve 47 First Relief Valve as Relief Valve of the Present Invention 48 Discharge Passage 50 Throttle 51 First Pilot Passage 52 Second pilot passage 54 Pressure reducing valve P pump T tank

Claims (2)

[Claims] 1. A pump, a sequence valve connected to the pump and opened when the pressure on the primary side reaches a predetermined pressure, a supply passage connected downstream of the sequence valve,
A plurality of control valves connected to the supply passage and in parallel with each other; a neutral passage connected to the supply passage and communicating the sequence valve and the tank when all of the plurality of control valves are neutral; A switching valve connected and parallel to the sequence valve, an unload valve connected downstream of the switching valve, a tank passage connected downstream of the unload valve and communicating with the tank, and a supply passage in the supply passage. A pressure reducing valve connected to a pump and parallel to the sequence valve and the switching valve; a main pilot passage connected to the pressure reducing valve; and a main pilot passage connected to the pressure reducing valve. Switching means for switching the plurality of control valves by controlling the pilot pressure guided to the When the unload valve is switched at the same time as the operation of the means and the communication between the pump and the tank passage is cut off, a predetermined pilot pressure is generated in the main pilot passage, while the pressure on the upstream side of the unload valve becomes a predetermined pressure. When it reaches, the sequence valve opens, and the pump and the supply passage communicate with each other. The pressure generated in this supply passage is guided to the pilot chamber of the switching valve to be switched, and the communication between the pump and the unload valve is established. A solenoid valve hydraulic control circuit characterized in that the solenoid valve is shut off. 2. A pump, a diversion type throttle switching valve connected to the pump and controlling a flow rate to first and second ports according to a switching position, and connected between the first port and the tank. Connected between the relief valve and the first port, disconnects the communication between the relief valve and the first port at the normal position, and connects the relief valve to the first port according to the switching position. And the pressure between the unload valve and the relief valve,
A discharge passage for discharging to a tank via an unload valve at a normal position, a throttle provided between the first port and the relief valve, and a pressure on the upstream side of the throttle to one pilot chamber of the throttle switching valve A first pilot passage that guides the pressure downstream of the throttle to the other pilot chamber of the throttle switching valve; a plurality of control valves that are connected to the second port and that are parallel to each other; When all of these control valves are in the neutral position, a neutral passage connecting the second port to the tank, a pressure reducing valve connected to the pump and parallel to the throttle switching valve, and a main valve connected to the pressure reducing valve. A pilot passage, and switching means for controlling the pilot pressure guided to the main pilot passage to switch the control valve. When the unload valve is switched, the communication between the pump and the second port is interrupted by the throttle switching valve, and when the fluid guided from the pressure reducing valve to the main pilot passage reaches a predetermined pressure, the unload valve is switched to the normal state. When the valve is returned to the position, the throttle switching valve is switched, and the second port is connected to the pump.