JPH0433046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a pressure reducing valve consisting of a main valve and a pilot valve.

<Prior Art> Conventionally, a two-port balanced piston type pressure reducing valve as shown in FIG. 9 has been known as this type of pressure reducing valve. (Hydraulics and Pneumatics Handbook, page 442, edited by Japan Hydraulics and Pneumatics Association, published April 20, 1975) This pressure reducing valve is the main valve 1.
The opening degree of the variable orifice 5 between the primary passage 3 and the secondary passage 4 is adjusted by the operation of the main spool 2. That is, the pressure in the secondary passage 4 reaches the set pressure of the pilot valve 15, and the pilot flow generated by opening the pilot valve 15 flows sequentially from the secondary passage 4 to the pilot passage 7,
A pilot chamber 6 on one end side of the main spool 2, a vent aperture 14 provided on the main spool 2, and a main spool 2
The poppet valve body 1 passes through the spring chamber 11 on the other end side.
6 to a pilot valve 15 having a and,
Vent throttle 14 determined by pilot flow rate
The main spool 2 is operated by the pressure difference between the upstream side and the downstream side of the variable orifice 5, that is, the pressure difference between the pressure in the pilot chamber 6 and the pressure in the spring chamber 11 in which the spring 12 is compressed. The opening degree is adjusted to reduce the pressure in the secondary passage 4 to a pressure corresponding to the set pressure of the pilot valve 15.

<Problems to be Solved by the Invention> However, in the conventional pressure reducing valve described above, the pilot pressure for operating the main spool 2 is transferred to the secondary passage 4.
Since it is guided from the side, there is a problem that the minimum control pressure becomes high. That is, if the spring 17 of the pilot valve 15 is unloaded, the poppet valve body 16 is
Even if the main spool 2 is fully opened, the secondary passage 4 must be
Since a pressure of 1.5 to 2 kg/cm ² is generally required as ^the pressure of The problem is that I can't.

Furthermore, in the conventional pressure reducing valve, the pilot pressure for operating the main spool 2 is obtained by the pilot flow (vent flow) from the secondary passage 4 to the pilot valve 15 passing through the vent throttle 14 of the main spool 2. Therefore, there is a problem that the space between the primary passage 3 and the secondary passage 4 cannot be completely closed. That is, to operate the main spool 2,
A vent flow is required, and the variable orifice 5 cannot be completely closed.

Therefore, the main object of the present invention is to be able to control the secondary pressure over the entire range from completely low pressure (approximately zero pressure) to approximately equal to the primary pressure, thereby controlling the actuator connected to the secondary passage. The object of the present invention is to enable the system to be started softly from a low pressure, and to operate even at a high pressure approximately equal to the primary pressure.

Another object of the present invention is to separate the passage for obtaining pilot pressure from the secondary passage from the passage for obtaining pilot flow for operating the main spool, thereby making it possible to completely close the secondary passage. It's about doing.

<Means for Solving the Problems> In order to achieve the above object, the pressure reducing valve of the present invention supplies pressure for operating the main spool 36 of the main valve 32 to the primary passage, as illustrated in FIGS. 37 through the pilot valve 33, and on the other hand, the pilot pressure that operates the pilot valve 33 is supplied to the main valve 3.
It is characterized in that it is led directly from the secondary passage 38 rather than from the spring chamber 43 of No. 2. In other words, main valve 3
The pilot passage 48 that obtains the pilot pressure for the pilot valve 33 is completely separated from the pilot passage 58 that obtains the pilot pressure for the pilot valve 33,
The pilot pressure for the main valve 32 is obtained from the primary passage 37 side by the pilot passage 48, while the pilot pressure for the pilot valve 33 is obtained from the secondary passage 38 by the pilot passage 58.
This is something that can be obtained from the side. More specifically, this pressure reducing valve is provided with a pressing means 45 at one end of the main spool 36, guides pilot pressure to a pilot chamber 46 at the other end of the main spool 36, and combines this pilot pressure with the pressing means 45. By operating the main spool 36 against the pressing force, the opening degree of the variable orifice 41 between the primary passage 37 and the secondary passage 38 is adjusted, and the pressure in the secondary passage 38 is reduced. The normally open main valve 32 to be controlled and the pilot chamber 46 at the other end of the main spool 36 are connected to the primary passage 37 and the tank 8.
A pilot passage 58 for guiding the pressure of the secondary passage 38 is provided in the pilot chamber 57 at one end of the valve body 52 which is switchably connected to the valve body 5, and pressing means 56, 56' are provided at the other end of the valve body 52. , the valve body 52 is operated by the pressure of the pilot chamber 57 opposing the pressing force of the pressing means 56, 56', and the pilot chamber 46 on the other end side of the main spool 36 is connected to the primary passage 37. It is characterized in that it consists of a pilot valve 33 which is switchably connected to the tank 85.

<Function> With the above configuration, in order to adjust the secondary pressure to approximately zero pressure, the pressing force of the pressing means 56 itself of the pilot valve 33 (see FIG. 1) or the force of an electromagnetic proportional solenoid or the like opposing the pressing means 56' is used. Biasing means 96
(See Fig. 5) Adjusts the biasing force of the secondary passage 38 as shown in Fig. 1 to balance the pressure of the secondary passage 38 and the pressing force of the pressing means 56, or Pressure and electromagnetic proportional solenoid 96
The actuation of the valve body of the pilot valve 33 by the balance of the pressing means 56' with the sum of the urging force of
Since the pressure in the primary passage 37 is led to the pilot chamber 46 of the main valve 32 via the pilot passage 48,
Even when the pressure in the secondary passage 38 is controlled to a state extremely close to zero pressure by the pressing means, the main spool 36 of the main valve 32 is operated and there is no pressure between the primary side and the secondary side. kept closed. Therefore, the pressure in the secondary passage 38 is controlled to an extremely low pressure (substantially zero pressure). In addition, by increasing the pressing force of the pressing means 56 of the pilot valve 33 or weakening the urging force of the urging means 96, the pressure introduced into the pilot chamber 46 of the main valve 32 is controlled by operating the pilot valve 33. By operating the main spool 36, the control pressure in the secondary passage 38 can be controlled to be approximately equal to the pressure in the primary passage 37 in the highest state. Further, although the pilot valve 33 extracts pilot pressure from the secondary passage 38, no vent flow is formed from the secondary passage 38, so that the variable orifice 41 can be completely closed.

<Examples> The present invention will be described in detail below with reference to illustrated examples.

As shown in FIG. 1, this pressure reducing valve 31 consists of a normally open main valve 32 and a pilot valve 33. The main valve 32 has a main spool 3 inside the main body 35.
6 are slidably fitted together, and the operation of this main spool 36 switches and connects the secondary port B to the primary port A or the tank port T, and the primary passage 37 connected to the primary port A and the 2 The opening and closing of a variable orifice 41 between the secondary passage 38 connected to the next port B is controlled. Main spool 36 above
A spring 45 as a pressing means is compressed in the spring chamber 43 at one end, and the pressure of the primary passage 37 is guided through a pilot passage 48 to a pilot chamber 46 at the other end of the main spool 36. That's what I do. A small diameter stopper 49 is provided at the end of the main spool 36 on the pilot chamber 46 side.

On the other hand, the pilot valve 33 is of a normally open type, with a spool-type valve body 52 slidably provided within the main body 51, and an electromagnetic proportional solenoid 56 as an example of a pressing means provided at one end of the valve body 52. There is. This electromagnetic proportional solenoid 56
Plunger 7 in plunger chamber 55 on one end side of 2
2 and a coil 73. The coil 73 generates an attractive force that is approximately proportional to the current value, regardless of the stroke, and the plunger 72 presses the valve body 52 with a force that is proportional to the current value.
A weak spring 59 is attached to the pilot chamber 57 at the other end of the valve body 52 to determine the rest position, and the pressure of the secondary passage 38 is guided through the pilot passage 58. Therefore, the valve body 52 of the pilot valve 33 is reciprocated by the balance between the pressure in the secondary passage 38 and the pressing force of the electromagnetic proportional solenoid 56. The pilot valve 33 is operated by the pressure control section 5 by the reciprocating operation of the valve body 52.
3, port l on the pilot chamber 46 side of the main valve 32 is connected to port m on the primary passage 37 side or port n leading to the tank 85 to control the pressure in the pilot chamber 46. ing. A throttle 81 is provided in the line 82 connecting the port n and the tank 85 to ensure stability in controlling the pressure in the pilot chamber 46 of the main valve 32.

Further, a hydraulic cylinder 65 is connected to the secondary passage 38 of the main valve 32. A tank 85 is connected to the tank port T of the main valve 32 via a line 86. A tank 85 is connected to the spring chamber 43 of the main valve 32 via a drain line 84, and a tank 85 is connected to the plunger chamber 55 of the pilot valve 33 via a drain line 83. A pressure source 77 is provided in the primary passage 37 of the main valve 32.
are connected.

In the above configuration, when the current value i applied to the coil 73 of the electromagnetic proportional solenoid 56 is zero, the valve body 52 moves completely upward because a weak spring is attached to the pilot chamber 57 of the pilot valve 33. Therefore, port l and port m communicate,
The pilot passage 48 is opened and the pressure in the primary passage 37 is introduced into the pilot chamber 46 of the main valve 32.
Therefore, the main spool 36 of the main valve 32 moves to the left in FIG. 1 while pressing the spring 45 due to the pressure of the primary passage 37 led to the pilot chamber 46.
The variable orifice 41 is closed and the pressure in the secondary passage 38 is controlled to approximately zero pressure.

In this way, this pressure reducing valve 31 guides the pilot pressure that operates the main spool 36 of the main valve 32 from the primary passage 37 side, so the pressure in the secondary passage 38 is controlled to an extremely low pressure close to zero pressure. The main spool 36 can be operated to perform pressure reduction control even in a state where the main spool 36 is in a state where the pressure is reduced, and the pressure in the secondary passage 38 can be controlled from a state extremely close to zero pressure. Since the pressure in the secondary passage 38 can be controlled to an extremely low pressure close to zero pressure in this way, the hydraulic cylinder 65 can be activated extremely softly and without a shock.

On the other hand, when the current value applied to the electromagnetic proportional solenoid 56 of the pilot valve 33 is increased, the pressing force of the plunger 72 of the electromagnetic proportional solenoid 56 and the pressure on the secondary passage 38 side are introduced into the pilot chamber 5.
By balancing the pressure of 7, the pilot valve 33
The valve body 52 operates and the pressure control unit 53 closes the port l.
is connected to port m or port n, the main spool 36 is reciprocated, and the variable orifice 4
1, the pressure in the secondary passage 38 is controlled by the electromagnetic proportional solenoid 5 of the pilot valve 33.
The pressure is controlled according to the current value applied to 6. By increasing the current value in this manner, the pressure in the secondary passage 38 can be controlled to a pressure approximately equal to the pressure in the primary passage 37. in this way,
This pressure reducing valve operates from an extremely low pressure close to zero pressure to the primary passage 3.
The pressure in the secondary passage 38 can be controlled over a wide range up to a pressure approximately equal to the pressure of 7.

Figure 2 shows a line showing that as the applied current value i increases, the secondary pressure P ₂ in the secondary passage 38 increases and reaches the same state as the primary pressure P ₁ in the primary passage 37, becoming saturated. It is a diagram. FIG. 3 is a diagram showing how the sum of internal leakage, which changes depending on the amount of overlap between the valve body 52 of the pilot valve 33 and the main valve body 51, and the internal leakage of the main valve, changes depending on the current value i. be. In addition, FIG. 4 shows the secondary pressure in the secondary passage 38.
While trying to control P ₂ to a constant pressure Pd, 1
When the pressure P ₁ in the secondary passage 37 is gradually increased, the primary pressure P ₁ in the primary passage 37 becomes the set pressure Pd.
The primary pressure P ₁ and _the secondary pressure P ₂ become the same pressure until the It is a diagram showing that secondary pressure _P2 is controlled to set pressure Pd.

This pressure reducing valve 31 also guides the pilot pressure for operating the main spool 36 of the main valve 32 from the primary passage 37 through the pilot passage 48, and supplies the pilot pressure for operating the pilot valve 33 to the pilot chamber 37. Since the secondary passage 38 is guided by the pilot passage 58 and does not form a vent flow via the spring chamber of the main valve as in the conventional case, when the main spool 36 of the main valve 32 closes the variable orifice 41, the secondary passage 38 can be completely closed. That is, the pilot flow in this pressure reducing valve 31 becomes approximately zero.

In addition, the spring chamber 43 of the main valve 32 is connected to the drain line 8
Since the plunger chamber 55 of the pilot valve 33 is connected to the tank 85 through the drain line 83, the main valve 32
Both the pilot valve 33 and the pilot valve 33 operate reliably and do not malfunction.

FIG. 5 shows another embodiment, in which the embodiment shown in FIG.
If the pressure is increased by increasing the pressure, the control secondary pressure _P2 increases, which is a forward characteristic.
If the current value i applied to the electromagnetic proportional solenoid 96 is increased, the control secondary pressure _P2 decreases, which has a reverse characteristic. The pressure reducing valve 3 shown in FIG.
The pilot valve 33 of No. 1 communicates between port l and port n in the normal state when the power is not energized, and the main valve 3
The two pilot chambers 46 are communicated with the tank 85. A spring 56' having a strong spring force as a pressing means is installed in the spring chamber 55 on one end side of the valve body 52 of the pilot valve 33, and a plunger 7 of the electromagnetic proportional solenoid 96 is installed in the pilot chamber 57.
2 is arranged to increase the pressing force of the plunger 72, thereby apparently weakening the spring 56' and lowering the control secondary pressure _P2 . The rest is the same as the embodiment shown in FIG. 1, so the same components as in FIG. 1 are given the same reference numerals and the explanation will be omitted.

FIG. 6 shows that the secondary pressure in the secondary passage 37 is initially
P ₂ is in the same state as the primary pressure P ₁ in the primary passage 37 and is saturated, but as the applied current value i increases, the secondary pressure P ₂ in the secondary passage 38 decreases. FIG. FIG. 7 is a diagram showing how the sum of internal leakage, which changes depending on the amount of overlap between the valve body 52 of the pilot valve 33 and the main valve body 51, and the internal leakage of the main valve, changes depending on the current value i. be. In addition, FIG. 8 shows the secondary pressure in the secondary passage 38.
While trying to control P ₂ to a constant pressure Pd, 1
When the pressure P ₁ in the secondary passage 37 is gradually increased, the primary pressure P ₁ in the primary passage 37 becomes the set pressure Pd.
The primary pressure P ₁ and _the secondary pressure P ₂ become the same pressure until the It is a diagram showing that the secondary pressure _P2 is controlled to the set pressure Pd.

In addition, in the above embodiment, as a pressure relief means for the secondary passage 38, by leaking fluid from the secondary passage 38 to the tank 85, it is possible to change the set pressure from a high pressure reduction value to a low pressure reduction value. However, instead of the above configuration, for example, when switching the set pressure from a high pressure reduction value to a low pressure reduction value using an on-off valve, open the on-off valve, release the pressure, and then close the valve. Well, various modifications may be used.

In the present invention, the main spool of the main valve and the spool-type valve body of the pilot valve may have either an overlap characteristic or an underlap characteristic during the transition period. Further, the pressing means may be a spring, an electromagnetic proportional solenoid, or the like, and the on-off solenoid may be controlled by pulse width modulation (PWM control).

<Effects of the Invention> As is clear from the above, the pressure reducing valve of the present invention guides the pressure of the primary passage to the pilot chamber of the main valve through the pilot passage, and controls the opening and closing of the pilot passage. By guiding the pressure in the secondary passage through the pilot passage, the pilot passage for operating the main valve and the pilot passage for operating the pilot valve are completely separated, and the main valve is controlled by the pressure in the primary passage. Since the main spool of the main valve can be operated even in a controlled state where the pressure in the secondary passage is extremely low, the pressure in the secondary passage can be reduced to zero. It can be controlled to an extremely low pressure close to 1
The pressure can be controlled to a high pressure approximately equal to the pressure in the next passage, and the pressure can be controlled over a wide range. Therefore, the actuator connected to this pressure reducing valve is
The actuator can be activated very softly and without shock from a low pressure, and the actuator can also be operated at a high pressure approximately equal to the primary pressure.

Furthermore, the pressure reducing valve of the present invention does not control the pressure by vent flow passing through the spring chamber of the main valve and the vent throttle provided in the main valve body, as in the conventional case, but rather controls the pressure in the secondary passage by controlling the pressure in the pilot valve. Since the pressure of the primary passage is introduced into the pilot chamber of the main valve, the secondary passage can be completely closed.

[Brief explanation of drawings]

Fig. 1 is a sectional view of one embodiment of the present invention;
Figures 6 and 6 are diagrams showing the relationship between current value and secondary pressure in the secondary passage, Figures 3 and 7 are diagrams showing internal leakage, and Figures 4 and 8 are diagrams showing the relationship between the secondary passage and the secondary passage. The primary pressure of P ₁
A diagram showing the relationship between and the secondary pressure P ₂ of the secondary passage,
FIG. 5 is an explanatory diagram showing another embodiment, and FIG. 9 is a sectional view of a conventional example. 31...Pressure reducing valve, 32...Main valve, 33...Pilot valve, 36...Main spool, 37...Primary passage, 38...
Secondary passage, 41... variable orifice, 43, 55...
Spring chamber, 45... Spring, 46, 57... Pilot chamber, 48, 58... Pilot passage, 52... Valve body.

Claims (1)

[Scope of Claims] 1. A pressing means 45 is provided at one end of the main spool 36, and a pilot pressure is introduced into a pilot chamber 46 at the other end of the main spool 36, so that this pilot pressure and the pressing force of the pressing means 45 are combined. By operating the main spool 36 in opposition to the above, the opening degree of the variable orifice 41 between the primary passage 37 and the secondary passage 38 is adjusted, and the pressure in the secondary passage 38 is controlled to be reduced. A normally open main valve 32 and a pilot chamber 4 at the other end of the main spool 36.
6, a pilot passage 58 which guides the pressure of the secondary passage 38 to the pilot chamber 57 on one end side of the valve body 52 which is connected to the primary passage 37 and the tank 85.
A pressing means 56 is provided on the other end side of the valve body 52.
56' is provided, and the valve body 52 is operated by the pressure of the pilot chamber 57 opposing the pressing force of the pressing means 56, 56', and the main spool 3 is operated.
The pilot chamber 46 on the other end side of 6 is connected to the primary passage 3
7 and tank 85.
A pressure reducing valve consisting of 3.