JPH0433045B2 - - 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, as this type of pressure reducing valve, a two-port balanced piston type as shown in FIG. 5 is known. (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 and one end side of the main spool 2. The poppet valve body 16 passes through the pilot chamber 6, the vent throttle 14 provided on the main spool 2, and the spring chamber 11 on the other end side of the main spool 2.
The pilot valve 15 having a flow rate is opened to allow water to flow into the tank. Then, due to the pressure difference between the upstream side and the downstream side of the vent throttle 14 determined by the pilot flow rate, 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 main spool 2 is operated to adjust the opening degree of the variable orifice 5, and the pressure in the secondary passage 4 is controlled by the pilot valve 15.
The pressure is controlled to be reduced to a pressure corresponding to the set value.

<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, vent flow is required to operate the main spool 2, 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 also to operate 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, as illustrated in FIG. It is characterized in that the pilot pressure for operating the pilot valve 33 is led directly from the secondary passage 38 rather than from the spring chamber 43 of the main valve 32. That is, a pilot passage 48 that obtains pilot pressure for the main valve 32
and the pilot passage 58 which obtains the pilot pressure for the pilot valve 33, and 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 primary passage 37 side. Pilot pressure is obtained from the secondary passage 38 side by a pilot passage 58. For more details,
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 force of the pressing means 45. By opposingly operating the main spool 36, the main valve 32 adjusts the opening degree of the variable orifice 41 between the primary passage 37 and the secondary passage 38, and the pressure in the primary passage 37 is adjusted to the above-mentioned level. A valve body 52 is interposed in the pilot passage 48 leading to the pilot chamber 46 on the other end side of the main spool 36, and a pressing means 56 is provided on one end side of the valve body 52, and the pilot passage 48 on the other end side of the valve body 52 is provided with a pressing means 56. A pilot passage 58 is provided in the chamber 57 to guide the pressure of the secondary passage 38, and the valve body 52 is operated by the pressure of the pilot chamber 57 opposing the pressing force of the pressing means 56, thereby controlling the primary passage 3.
7 pressure to a pilot chamber 46 at the other end of the main spool 36.

<Function> With the above configuration, when the pressing means 56 of the pilot valve 33 is adjusted to adjust the secondary pressure to approximately zero pressure,
Due to the operation of the valve body of the pilot valve 33 due to the balance between the pressure in the secondary passage 38 and the pressing means 56, 1
Since the pressure in the secondary passage 37 is guided to the pilot chamber 46 of the main valve 32 via the pilot passage 48, the main spool 36 of the main valve 32 is operated, and the state between the primary side and the secondary side is closed. is maintained. Therefore, the pressure in the secondary passage 38 is extremely low (nearly zero pressure).
controlled by. In addition, by increasing the pressing force of the pressing means 56 of the pilot valve 33, the pressure introduced into the pilot chamber 46 of the main valve 32 is controlled by the operation of the pilot valve 33, and the main spool 36 is operated, so that the pressure reaches the highest level. In this state, the control pressure in the secondary passage 38 can be controlled to be approximately equal to the pressure in the primary passage 37. Further, although the pilot valve 33 extracts pilot pressure from the secondary passage 38,
Since no vent flow is formed from this point on, it is possible to completely close the secondary passage 38.

<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 is a main valve 3.
2 and a pilot valve 33. The main valve 32 has a main spool 36 slidably fitted into the main body 35, and when the main spool 36 is operated, the primary passage 3
7 and the secondary passage 38 is controlled to open and close. A spring 45 as a pressing means is compressed in a spring chamber 43 at one end of the main spool 36, and a pilot chamber 46 at the other end of the main spool 36 receives the pressure of the primary passage 37 into a pilot passage 48. I am trying to guide you through this. 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 has a spool-type valve body 52 slidably provided in the main body 51, and a pressure regulating spring 56 as a pressing means is compressed into a spring chamber 55 at one end of the valve body 52. The pressing force of the pressure regulating spring 56 can be adjusted by an adjusting handle 57. A pilot chamber 57 on the other end side of the valve body 52 is connected to a secondary passage 3 via a pilot passage 58.
Leading to the pressure of 8. 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 pressure regulating spring 56. The pilot valve 33 is controlled by the pressure control section 53 by the reciprocating operation of the valve body 52 to control the primary passage 37 and the pilot chamber 4 of the main valve 32.
The opening/closing control of a pilot passage 48 connecting to 6 is controlled. A tank 63 is connected to the pilot passage 48 between the pilot chamber 46 of the main valve 32 and the pilot valve 33 by a line 62 having a throttle 61 for generating pilot pressure.

Further, a hydraulic cylinder 65 is connected to the secondary passage 38 of the main valve 32. A tank 68 is connected to the secondary passage 38 by a line 67 provided with a throttle 66 for releasing pressure on the secondary side. A tank 73 is connected to the spring chamber 43 of the main valve 32 through a drain line 71.
A tank 76 is connected to the spring chamber 55 via a drain line 75. A pressure source 77 is connected to the primary passage 37 of the main valve 32 .

In the above configuration, it is assumed that the pressure in the secondary passage 38 is controlled to a pressure close to zero pressure by loosening the adjustment handle 57 of the pilot valve 33 and setting the spring force of the pressure regulating spring 56 to its weakest state. Then, the valve body 52 of the pilot valve 33 operates due to the balance between the pressure in the secondary passage 38 led to the pilot chamber 57 and the spring force of the pressure regulating spring 56, and
is opened and closed to guide the pressure in the primary passage 37 to the pilot chamber 46 of the main valve 32. Therefore, the main spool 36 of the main valve 32 presses the spring 45 due to the pressure of the primary passage 37 led to the pilot chamber 46 while
It moves to the left in the figure to close the variable orifice 41 and control the pressure in the secondary passage 38 to approximately zero pressure.

In this way, since this pressure reducing valve 31 guides the pilot valve that operates the main spool 36 of the main valve 32 from the primary passage 37 side, 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, if the adjustment handle 57 of the pilot valve 33 is operated to increase the spring force of the pressure adjustment spring 56,
Due to the balance between the spring force of the pressure regulating spring 56 and the pressure in the pilot chamber 57 to which the pressure on the secondary passage 38 side is guided, the valve element 52 of the pilot valve 33 operates, and the pressure control section 53 opens and closes the pilot passage 48. The pressure in the primary passage 37 is guided to the pilot chamber 46 of the main valve 32, and the main spool 36 is reciprocated.
By controlling the opening degree of the variable orifice 41, the pressure in the secondary passage 38 is controlled to a pressure corresponding to the spring force of the pressure regulating spring 56 of the pilot valve 33. By increasing the spring force of the pressure regulating spring 56 in this manner, the pressure in the secondary passage 38 can be controlled to a pressure substantially equal to the pressure in the primary passage 37.
In this way, this pressure reducing valve can control the pressure in the secondary passage 38 over a wide range from an extremely low pressure close to zero pressure to a pressure approximately equal to the pressure in the primary passage 37.

FIG. 2 shows that as the strength of the spring force of the pressure regulating spring 56 is increased, 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. FIG. Also, the third
The figure shows a state where the secondary pressure P ₂ in the secondary passage 38 is being controlled to a constant pressure Pd, and the pressure P ₁ in the primary passage 37 is being controlled to a constant pressure Pd.
When the pressure is gradually increased, the primary pressure _P1 in the primary passage 37 reaches the set pressure Pd.
P ₁ and the secondary pressure P ₂ become the same pressure, but when the primary pressure P ₁ in the primary passage 37 reaches the set pressure Pd, the operation of the pilot valve 33 and the main valve 32 causes the secondary pressure to increase.
FIG. 2 is a diagram showing that P ₂ is controlled to a set pressure Pd.

A throttle 61 for generating pilot pressure provided in a pilot passage 62 branched from the pilot passage 48 functions to generate pilot pressure to the main valve 32 and to stabilize the operation of the main spool 36 of the main valve 32. A throttle 66 provided in a pilot line 67 connected to the secondary passage 38 serves to stabilize the pressure in the secondary passage 67 and keep it constant. Further, the spring chamber 43 of the main valve 32 is connected to the tank 73 through the drain line 71, and the spring chamber 55 of the pilot valve 33 is connected to the tank 76 through the drain line 75, so that the main valve 32 and Both pilot valves 33 operate reliably and do not malfunction.

Further, this pressure reducing valve 31 guides pilot pressure for operating the main spool 36 of the main valve 32 from the primary passage 37 via a pilot passage 48, and directs pilot pressure for operating the pilot valve 33 to the secondary passage 38. Since the vent flow is not formed through 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 space between the secondary passage 37 and the secondary passage 38 can be completely closed.

FIG. 4 shows another embodiment, in which the valve body 82 of the pilot valve 33 is constituted by a poppet valve, and the only difference is that the chamber on the pressure regulating spring 56 side and the pilot chamber 46 are connected by a pilot passage 48. This is different from the embodiment shown in FIG. A pilot chamber 57 is formed by a piston 88 formed at the tip of the poppet valve 82, and an auxiliary spring 87 is compressed into this pilot chamber 57. Above poppet valve body 8
2 is pressed toward the seat 91 by a pressure regulating spring 56. The vertical movement of the poppet valve body 82 opens and closes a pilot passage 48 that guides the pressure in the primary passage 37 to the pilot chamber 46 of the main valve 32. The pressure of the secondary passage 38 is introduced to the pilot chamber 57 of the pilot valve 33 through a pilot passage 58.

While the main valve is operating, a pressure (constant) corresponding to the spring 45 is generated in the pilot chamber 46, and this pressure is generated in the spring chamber 45.
It acts on By setting the spring 87 to a corresponding pressure, the variable orifice 41 can be completely closed.

The other configurations are the same as in FIG. 1, and the same components as in FIG. 1 are given the same reference numerals and explanations will be omitted.

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 68, 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.

<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]

Figure 1 is a sectional view of an embodiment of the present invention, Figure 2 is a diagram showing the relationship between the strength of the pressure regulating spring and the secondary pressure in the secondary passage, and Figure 3 is the primary pressure in the primary passage. A diagram showing the relationship between P ₁ and the secondary pressure P ₂ of the secondary passage, FIG. 4 is an explanatory diagram showing the main part of another embodiment, and FIG. 5 is a sectional view of the 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. a main valve 32 that adjusts the opening degree of the variable orifice 41 between the primary passage 37 and the secondary passage 38 by operating the main spool 36 in opposition to each other; and a pressure in the primary passage 37. The above main spool 36
A valve body 52 is interposed in the pilot passage 48 leading to the pilot chamber 46 on the other end side, a pressing means 56 is provided on one end side of the valve body 52, and the pilot passage 48 on the other end side of the valve body 52 is provided with a pressing means 56. A pilot passage 58 is provided to guide the pressure of the secondary passage 38, and the valve element 52 is operated by the pressure of the pilot chamber 57 opposing the pressing force of the pressing means 56, thereby controlling the pressure of the secondary passage 38.
A pressure reducing valve consisting of a pilot valve 33 that guides the pressure in the next passage 37 to a pilot chamber 46 at the other end of the main spool 36.