JP2540891B2 - Pilot pressure generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a pilot pressure generator.

(Prior Art) Generally, there are two methods for generating pilot pressure in a hydraulic circuit. One is a method of obtaining a pilot pressure by another pump, and a method of keeping the minimum circuit pressure of the hydraulic circuit above the pilot pressure. In the former case, there is a problem that the apparatus becomes large and the cost becomes high because another pump is used, and in the latter case, there is a problem that the energy loss becomes large because it is necessary to keep the minimum circuit pressure at or above the pilot pressure.

The latter specific hydraulic circuit configuration is configured as shown in FIG. The pilot operation switching valves 1 and 2 can be switched by operating the manual switching valves 3 and 4. As is clear from this hydraulic circuit, when unloading, the hydraulic oil from the P port turns on the switching valves 1 and 2 and the large flow rate.
The tank T is connected via the center circuit connecting the off valve (solenoid valve) 5.
The pressure on the side supplied to the manual switching valves 3 and 4 via the pressure reducing valve 6 becomes lower than the pilot pressure, and switching of the switching valves 1 and 2 based on the operation of the manual switching valves 3 and 4 cannot be performed. It is like this.

To enable the switching of the switching valves 1 and 2, the large flow rate on / off valve 5 is closed, and the hydraulic oil from the P port flowing into the tank T through the center circuit is shut off to cut off the pressure at the P port. Raise. When the pressure at the P port rises and becomes equal to or higher than the pilot pressure, the pressure reducing valve 6 operates to obtain the pilot pressure, and the manual switching valves 3 and 4 can switch the switching valves 1 and 2.

(Problems to be solved by the invention) However, in the hydraulic circuit, a large flow rate
An off-valve 5 is required, and the on-off valve 5 directly controls a large flow rate of hydraulic oil.
It required a large value of drive current. Further, the pressure resistance must be high, and there is a problem in cost.

An object of the present invention is to solve the above problems, to use a small and small power consumption ON / OFF valve for pilot pressure generation, which can reliably generate pilot pressure. To provide.

Configuration of the Invention (Means for Solving Problems) In order to achieve the above object, the present invention shuts off a circuit communicating with an input port or a drain port of a pilot operation switching valve to which hydraulic oil from a hydraulic pump is supplied. In a pilot pressure generator that raises the pressure of hydraulic oil from a hydraulic pump to obtain the pilot pressure of the pilot operation switching valve, it is provided on the circuit and cuts off from the position communicating hydraulic oil from the hydraulic pump. A valve body that can be switched between different positions, a pressure chamber that is provided at one end of the valve body, and that moves the valve body in the blocking direction by inflowing hydraulic oil, and a pressure chamber that is provided upstream of the pressure chamber. A pressure reducing means for reducing the pressure of the hydraulic oil flowing into the pressure chamber, one end connected to the pressure chamber and the other end connected to the tank, and the circuit and the pilot Operation The pilot passage leading to the switch valve is disposed on a passage provided independently, the pilot pressure generating device comprising a solenoid valve for opening and closing between the pressure chamber and the tank in which the gist thereof.

(Operation) When the electromagnetic on-off valve closes, the pressure of the pressure chamber rises due to the hydraulic oil flowing in, moving the valve element in the shut-off direction and shutting off the circuit. At this time, the pressure inside the pressure chamber is held at the pressure reduced by the pressure reducing means, and the pressure chamber moves.
On the other hand, the solenoid on-off valve shuts off the hydraulic oil of the pressure chamber where the pressure is reduced. Here, the electromagnetic on-off valve has one end connected to the pressure chamber and the other end connected to the tank,
Moreover, since it is arranged on a passage provided independently of the pilot passage leading to the circuit and the pilot operation switching valve, the electromagnetic opening / closing valve is a low-pressure / low-flow rate hydraulic oil flowing into the pressure chamber via the pressure reducing means. It does not require a large flow rate type on / off valve as in the past.

(Example) Below. An embodiment of the present invention will be described with reference to the drawings. In FIG. 1, two 6-port three-position switching valves (hereinafter, referred to as first and second switching valves) 11 and 12 as pilot-operated switching valves are respectively set at three positions by pilot pressure from a pilot pressure generator 19 described later. Is controlled to switch. The hydraulic oil supplied from the P port of the oil pump (not shown) via the flow dividing valve 13 is supplied from the C1 port of the first switching valve 11 and the C2 port of the second switching valve 12.
Oil is supplied to each hydraulic device from the C3 port. Also, the first
A tank T is connected via a relief valve 14 between the switching valve 11 and the flow dividing valve 13.

Next, a pilot pressure generator for controlling the switching of the first and second switching valves 11 and 12 with pilot pressure will be described with reference to FIGS. 1 and 2.

The body 20 of the pilot pressure generator 19 includes a pressure reducing unit for keeping the pilot pressure constant, and the first and second
And a drive unit that opens and closes an unload circuit 15 that connects the switching valves 11 and 12.

Explaining the depressurizing portion of the body 20, a valve chamber 21 is provided on the left side of the body 20 and a large diameter portion 21a is formed inside thereof. The valve chamber 21 has the large diameter portion 21a with the first and second portions.
Supply port 2 that supplies pilot pressure to the switching valves 11 and 12
2, and a small diameter portion 21b on the left side (outside) of the large diameter portion 21a is provided with an inlet port 23 communicating with the P port. The needle valve 24 consists of a needle 24a, a spring 24b and a pilot pressure adjusting screw 24c, the valve body of which closes the outer opening of the valve chamber 21 and the pilot pressure in the valve chamber 21 is adjusted by adjusting the adjusting screw 24c. To do.

A cylindrical tubular reducing piston 25 disposed in the valve chamber 21 has a large-diameter portion 25a located in the large-diameter portion 21a of the valve chamber 21 and a medium-diameter portion fitted in the small-diameter portion 21b of the valve chamber 21. 25b is formed, and a small diameter portion 25c is formed between the large diameter portion 25a and the medium diameter portion 25b in a tapered shape so that the right side is continuous with the large diameter portion 25a. Port 23 and supply port 22
And are communicated with each other in the valve chamber 21.
In addition, an orifice is provided on the right end surface of the reducing piston 25.
26 is formed, and the right end face and the inner side communicate with each other through this orifice 26.

One end of the spring 27 arranged between the piston 25 and the needle valve 24 engages with the inner end of the reducing piston 25, and the other end engages with the side wall surface of the valve chamber of the needle valve 24. An elastic force that urges the piston 25 to the right (inward) is applied to the piston 25.

And this needle valve 24, reducing piston
The decompression unit composed of 25 parts constitutes decompression means.

Unload circuit 1 connecting the first and second switching valves 11 and 12
Explaining the drive unit that opens and closes 5, the body 20
In the center position of the spool accommodating chamber 30, the pressure chamber 31 is formed by expanding the chamber 30 on the left side of the accommodating chamber 30, and a spool 32 as a valve element is disposed in the accommodating chamber 30. Same spool 32
The left and right movements of the second opening / closing switch between the inlet port 33 communicating with the drain port of the second switching valve 12 and the tank port 34 communicating with the tank T.

A through hole 35 is formed in the spool 32, and an accommodation chamber 35a for accommodating the piston 36 is formed by expanding the inside of the left side portion of the through hole 35. A spring 37 is arranged in the accommodation chamber 35a, and the spring 36 applies an elastic force to the left side of the piston 36. Further, a push rod 38 is arranged in the through hole 35 so that the right end portion thereof projects from the hole 35. When the piston 36 moves rightward against the elastic force of the spring 37, the push rod 38 is pushed rightward by the piston 36. An orifice 39 is formed on the left side wall surface of the pressure chamber 31,
And the valve chamber 21 are connected via an orifice 39.

A case storage chamber 40 having a large diameter portion 40a and a small diameter portion 40b is formed on the right side of the storage chamber 30, and left and right drain passages 4 communicating with the tank T are formed on both sides of the large diameter portion 40a.
1,42 are formed. Case 4 arranged on the large diameter part 40a
3 is arranged so as to be movable in the left-right direction within the large diameter portion 40a, and a return spring 44 arranged in the small diameter portion 40b imparts an elastic force to the left. When the case 43 is at the right end position against the elastic force of the return spring 44, the right drain passage 42 is closed by the case 43.

The case 43 has through holes 43a and 43b formed on both side surfaces thereof,
The push rod 3 is pushed inward through the left through hole 43a.
The tip of 8 is protruding. The closed cylindrical plunger 45 housed in the case 43 has its left closed portion in contact with the push rod 38, and is elastic to the right by a spring 46 arranged between the right opening and the case 43. Power is given. An orifice 47 is formed on the outer surface of the plunger 45.

Further, the pressure chamber 31 and the small-diameter portion 40b of the case accommodating chamber 40 are provided with passages 48 and 49, respectively, which are communicated with each other through an on / off valve 50 as an electromagnetic opening / closing valve.

Next, the pilot pressure generator configured as described above
The function of 19 will be described.

Now, as shown in FIGS. 1 and 2, the spool 32 is in the neutral position and the inlet port 33 and the tank port 34 are in communication with each other, and the on / off valve 50 is in the off state (opened) and the passage 48 is opened. When communicating with 49, when unloading, first
And the hydraulic oil supplied via the second switching valves 11 and 12 is sent to the tank T via the inlet port 33 and the tank port 34, and the pressure at the P port is the first and second switching valves 11 and 12. The pilot pressure of 12 is low. Further, the hydraulic oil fed from the valve chamber 21 of the pressure reducing section to the pressure chamber 31 via the orifice 39 is provided with a passage 48, an on / off valve 50, a passage 49, a storage chamber.
Oil is sent to the tank T through the passage 40 and the passage 42.

During this unloading, when the on / off valve 50 receives the pilot pressure command signal and turns on and closes, the pressure chamber
The pressure of 31 rises to the pressure of P port. This increase in pressure causes the piston 36 housed in the spool 32 to move to the right against the elastic force of the spring 37, pushing the push rod 38 to the right. Based on this movement to the right, the push rod 38 pushes the plunger 45 in the case 43 against the elastic force of the spring 46, and retracts the plunger 45 to the right.

Further, when the pressure in the pressure chamber 31 rises, the spool 32
Starts moving to the right. Based on the movement of the spool 32, the case 43 is pushed and resists the elastic force of the return spring 44 to retreat to the right to close the passage 42. At this time, the plunger 45 retracts to the right relative to the case 43, and the small-diameter portion 40b of the case housing chamber 40 and the passage 41 communicate with each other through the plunger 45 and the orifice 47. The movement of the spool 32 to the right is not hindered.

As the spool 32 moves to the right, the unload circuit
15 starts to be blocked, the pressure on the inlet port 33 side rises,
That is, the pressure at the P port rises. Then, when the pressure at the P port rises above the pilot pressure, the pressure reducing section operates to make the pressure at the supply port 22 constant, and from this point, the pilot pressure is supplied to the first and second switching valves 11 and 12 to perform the switching operation. It becomes possible.

In the moving operation of the spool 32, when the P port pressure rises, the pressure in the pressure chamber 31 rises, and the moving speed of the spool 32 to the right further increases. The case 43 has a large diameter portion 40a and a small diameter portion 40b of the case housing chamber 40.
The step of the spool 32 is brought into contact with the step portion and the movement of the spool 32 is completed.

When the spool 32 has completely moved, when the on / off valve 50 is turned off and opened, the passages 48 and 49 communicate with each other, and the hydraulic oil in the pressure chamber 31 flows through the orifice 47 and the passage 41 provided in the plunger 45. Through the tank T.

A pressure loss amount due to the hydraulic oil flowing out through the orifice 47 is generated in the small diameter portion 40b of the case housing chamber 40, and the elastic force of the springs 37 and 46 causes the plunger 4 to move.
5 moves to the left and closes the left through hole 43a of the case 43.
Due to this blockage, the pressures in the pressure chamber 31 and the small-diameter portion 40b become the same, and since the tank T is also blocked, the spool 32 is moved to the left based on the difference in cross-sectional area between the spool 32 and the case 43. To be

This moving force is applied to the spool 32 by the unload circuit 15.
Since it is larger than the flow force applied to, the spool 32 can be easily returned to the initial position.

As described above, in this embodiment, when the on / off valve 50 is closed, the spool 32 is surely moved to the right to block the unload circuit 15 and raise the pressure of the P port to the pilot pressure. You can In this case, when the P port pressure rises, the pressure in the pressure chamber 31 also rises, and accordingly, the moving speed of the spool 32 to the right further increases, so that the pilot pressure can be generated quickly. it can.

When unloading, spool 32 and case 43
Based on the difference in the cross-sectional area of, the unload circuit 15 is configured to move the spool 32 to the left with a force larger than the flow force applied to the spool 32 to return to the initial position.
The unloading state can be reliably achieved with low pressure.

Moreover, when the pilot pressure is generated from the unloading state, the on / off valve 50 moves from the valve chamber 21 of the pressure reducing unit to the pressure chamber.
It is only necessary to open and close a small amount of hydraulic oil that has partially flown into 31, and there is no need for a large flow rate on / off valve as in the past. Moreover, since the maximum pressure in the pressure chamber 31 is the same as the pilot pressure generated at the supply port 22, the high-speed on / off valve 50 may be an on / off valve that can withstand this pilot pressure. Therefore, as the on / off valve 50 in this embodiment, it is possible to use an on / off valve having a small withstand voltage, a small size, a small drive current, and an advantageous cost.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the drain port side of the second switching valve 12 is closed and the pilot pressure generator 60 is provided on the circuit connecting the input port of the first switching valve 11 and the flow dividing valve 13. Further, the P port is configured to supply pilot pressure to each switching valve 11, 12 via the pressure reducing valve 59.

A main piston 63 is arranged in a valve chamber 62 of a body 61 of the pressure generator 60. Main piston as valve body
63 has a large diameter portion 63a on the left side and a medium diameter portion 63b on the right side, and the right end portion of the medium diameter portion 63b is formed into a taper shape to form a seat surface 63c so that the drain passage 64 leading to the tank T is closed. Has become. Also, a small diameter portion is provided between the large diameter portion 63a and the medium diameter portion 63b.
63d is formed to connect the flow dividing valve 13 and the first switching valve 11 to each other.

A housing recess 65 is formed on the left end surface of the main piston 63, and a communication hole having a smaller diameter than the housing recess 65 is formed on the inner end thereof.
66 is formed. An orifice 67 communicating with the communication hole 66 is formed outside the small diameter portion 63d.

On the left side of the valve chamber 62, a needle 68a, a spring 68b,
Needle valve 68 as pressure reducing means consisting of adjusting screw 68c etc.
The valve chamber of the needle valve 68 communicates the drain passage 64 with the tank T, and forms a pressure chamber 69 between the main pistons 63.

The pressure chamber 69 is provided with a spring 70 having one end engaged with the needle valve 68 and the other end engaged with the inner end of the accommodation recess 65, and the spring 70 applies a right elastic force to the piston 63. To do. An on / off valve 71 as an electromagnetic opening / closing valve is arranged between the pressure chamber 69 and the tank T to control the pressure in the pressure chamber 69. The pressure chamber 69 is connected to the tank T via the first switching valve 11, the pressure reducing valve 72 and the needle valve 68.

Next, the operation of the pressure generating device 60 configured as described above will be described.

Now, when the on / off valve 71 is in the off state and is open circuit, the main piston 63 retracts to the left. Therefore, the seat surface 63c of the main piston 63 is opened, and the hydraulic oil from the P port flows into the tank T through the drain passage 64, so that it is in the unload state. In addition, this main piston
The leftward movement of 63 is determined by the opening pressure of needle 68a at needle valve 68.

When the on / off valve 71 is turned on and closed from this unloading state, the hydraulic oil flowing in through the orifice 67 and the communication hole 66 formed in the small diameter portion 63d is blocked by the on / off valve 71. Therefore, the pressure in the pressure chamber 69 increases.
Due to this rise, the main piston 63 moves to the right,
The seat surface 63c is blocked by the drain passage 64.

With the closing of the drain passage 64, the pressure of the P port valve rises, and when the pressure exceeds the pilot pressure, the pressure reducing valve 59 operates and the pilot pressure is supplied to each of the switching valves 11 and 12.

In order to change from this state to the unloading state, if the on / off valve 71 is turned off, that is, opened, the pressure in the pressure chamber 69 decreases, and the main piston 63 moves to the left and enters the unloading state.

As described above, the pilot pressure generator 60 of the present embodiment has a simpler structure than the pilot pressure generator 19 of the above embodiments, and can surely generate the pilot pressure.

Further, also in this embodiment, when the pilot pressure is generated from the unloading state, the on / off valve 71 only has to open and close a small amount of hydraulic oil that partially flows into the pressure chamber 69,
It does not require a large flow rate on / off valve as in the past. Moreover, since the maximum pressure of the pressure chamber 69 is a small pressure determined by the needle valve 68, the on / off valve 71 may be an on / off valve that can withstand this pilot pressure. Therefore, as the on / off valve 71 in this embodiment, a small withstand voltage, a small size, a small drive current, and an advantageous cost can be used.

EFFECTS OF THE INVENTION As described in detail above, according to the present invention, it is possible to use an on / off valve that is small in size and consumes less power for generating pilot pressure, and is also excellent in reliably generating pilot pressure. Have the effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a hydraulic circuit for generating pilot pressure of a pilot operation switching valve, FIG. 2 is a cross-sectional view of essential parts showing the structure of a pilot pressure generator, and FIG. Second
4 is a hydraulic circuit for generating pilot pressure of a conventional pilot operation switching valve, which is a cross-sectional view of a main part showing a structure of a pilot pressure generator in the embodiment of FIG. In the figure, 11 is a first switching valve as a pilot operation switching valve, 12 is a second switching valve as a pilot operation switching valve,
13 is a diversion valve, 15 is an unload circuit, 19 is a pilot pressure generator, 20 is a body, 21 is a valve chamber, 22 is a supply port, 23
Is an inlet port, 24 is a needle valve constituting a pressure reducing means, 25
Is a reducing piston constituting a pressure reducing means, 26 is an orifice, 27 is a spring, 30 is a spool accommodating chamber, 31 is a pressure chamber, 32 is a spool as a valve body, 33 is an inlet port,
34 is a tank port, 38 is a push rod, 39 is an orifice, 40 is a case chamber, 41 and 42 are drain passages, 43 is a case, 44 is a return spring, 45 is a plunger, 46 is a spring, 47 is an orifice, 48, 49 is a passage, 50 is an on / off valve as an electromagnetic on-off valve, 60 is a pilot pressure generator, 63 is a main piston as a valve body, 67 is an orifice, 68 is a needle valve as a pressure reducing means, 69 is a pressure chamber, 70
Is a spring, 71 is an on-off valve as an electromagnetic on-off valve, 72
Is a pressure reducing valve.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-61-45101 (JP, A) JP-A-54-10869 (JP, A) Actually opened 55-22535 (JP, U) Actual-opened Sho 55- 50352 (JP, U)

Claims (1)

(57) [Claims] 1. A circuit for communicating with an input port or a drain port of a pilot operation switching valve to which hydraulic oil is supplied from a hydraulic pump is cut off to increase the pressure of the hydraulic oil from the hydraulic pump to increase the pressure of the pilot operation switching valve. In a pilot pressure generator that obtains pilot pressure, a valve body that is provided on the circuit and that can switch between a position for communicating hydraulic oil from a hydraulic pump and a position for shutting off the hydraulic oil, and one end of the valve body A pressure chamber that is provided to move the valve body in the shut-off direction by inflowing hydraulic oil; and a pressure reducing unit that is provided on the upstream side of the pressure chamber and reduces the pressure of the operating oil that flows into the pressure chamber. , One end of which is connected to the pressure chamber and the other end of which is connected to the tank, and which is provided on a passage independent of the pilot passage leading to the circuit and the pilot operation switching valve. A pilot pressure generator provided with an electromagnetic opening / closing valve arranged to open / close between the pressure chamber and the tank.