JPH0440051Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention reduces the hydraulic pressure from a hydraulic pressure source to control the switching of a directional valve, etc. in a main circuit, for example. The present invention relates to a pressure-reducing pilot valve capable of outputting an output, and particularly relates to a pressure-reducing pilot valve having a plurality of shaft holes drilled into the casing for inserting a plurality of spools into the casing.

[Prior art]

In recent years, construction machinery, civil engineering machinery, etc. have become larger, faster, and more sophisticated, and as a result, hydraulic circuits have become more complex, and the flow rate of pressure oil flowing through the hydraulic circuits has also tended to increase. For this reason, large-capacity hydraulic pumps are being used, and directional control valves and the like are also becoming larger. Therefore, recently, in order to easily and smoothly perform switching control of a directional switching valve, tilting control of a variable displacement pump, etc., a hydraulic pilot system has been adopted in which these controls are performed using a pilot valve. As this type of pilot valve, a pressure reducing valve type pilot valve whose pilot pressure can be easily controlled is widely used.

Therefore, FIG. 2 shows a pressure reducing valve type pilot valve according to the prior art.

In the figure, 1 is a casing that constitutes the pilot valve body, and inside the casing 1 there is a pump port 3 into which pressure oil from a hydraulic pump 2 flows, and a tank port 5 which is in continuous communication with a tank 4, each having a substantially L shape. A pair of output ports 6, 6 are provided between the pump port 3 and the tank port 5, which communicate with each other through shaft holes 8, which will be described later. Each output port 6 is connected to each pilot chamber (not shown) of the directional control valve via piping 7, 7, and the pressure inside each output port 6 controls switching of the directional control valve. It's summery. Note that the pump port 3 and tank port 5 do not necessarily have to be formed in a substantially L-shape, and each output port 6 may be formed in a substantially L-shape.

Reference numerals 8 and 8 denote a pair of shaft holes located symmetrically within the casing 1 and provided through the casing 1 in the axial direction, and the upper end side of each shaft hole 8 is provided with a large diameter spring chamber 9, 9. Each spring chamber 9 is constantly communicated with the tank port 5 via a passage 10. Further, pressure chambers 11, 11 are provided on the lower end side of each shaft hole 8, and are always in communication with the output port 6 via an oil passage 13F of each spool 13, which will be described later.
The lower end side of is closed by each plug 21 described later. Each shaft hole 8 has a spool 13 located between each spring chamber 9 and each output port 6, between each output port 6 and pump port 3, and between each pump port 3 and each pressure chamber 11. sliding hole 8
A, 8B, and 8C are formed. Of the sliding holes 8A, 8B, 8C, the sliding holes 8A, 8B
serves as a flow path for oil fluid, and is selectively opened and closed by each spool 13, so that each output port 6 is communicated with either the pump port 3 or the tank port 5.

Here, each shaft hole 8 is finished by high-precision hole machining in the sliding holes 8A, 8B, and 8C through which each spool 13 slides, that is, with high-precision cylindricity, roundness, and finished surface. It is also formed with a through hole passing through the casing 1 in the axial direction to ensure the
After drilling this through hole, slide holes 8A, 8B, 8C
The holes are machined with high precision. Each shaft hole 8 communicates with the pump port 3, each output port 6, and the tank port 5, and a passage 12 is bored in a portion corresponding to the pump port 3 so as to communicate between the shaft holes 8. ing. On the other hand, step portions 9A, 9A are provided in each spring chamber 9 to protrude radially inward, and each step portion 9A restricts the axial displacement of each pusher 16, which will be described later, within a predetermined range. ing.

Reference numerals 13 and 13 denote spools that are slidably inserted into each shaft hole 8, and each spool 13 has a lower end surface located within each pressure chamber 11 to connect each pressure chamber 11 to the pump port 3. a large diameter portion 13A that opens and closes the output port 6 with respect to the pump port 3 by sliding in the sliding holes 8B and 8C; a small-diameter portion 13B extending from the upper end of the small-diameter portion 13B; and an annular portion 13C that protrudes in the radial direction from the upper end of the small-diameter portion 13B and slides within the slide hole 8A to open and close the output port 6 with respect to the tank port 5. , a shaft portion 13D extending in the axial direction from the annular portion 13C and extending inside the spring chamber 9;
and a head 13E provided at the upper end of the shaft portion 13D.
The output port 6 is selectively communicated with either the pump port 3 or the tank port 5 by the large diameter portion 13A and the annular portion 13C. Further, each spool 13 is provided with an oil passage 13F in the axial and radial directions from the lower end surface of the large diameter portion 13A to the circumferential surface of the small diameter portion 13B.
The oil passage 13F constantly communicates the pressure chamber 11 with the output port 6. And large diameter part 13A
The pressure inside the pressure chamber 11 acts on the lower end surface of the spool 13, and when the inside of the pressure chamber 11 becomes high pressure through the output port 6, the spool 13 is pressed upward by this pressure. There is.

14, 14 are fitted on the upper end side of each spring chamber 9,
With the bushing that covers the upper end of each shaft hole 8,
Each bushing 14 is prevented from coming off by an upper cover 15 screwed onto the upper end surface of the casing 1. 16, 16 are slidably inserted into each bushing 14, and are connected to each bushing 14 and the top lid 1.
5, and the base end of each pusher 16 is provided with flanges 16A, 1 in the radial direction.
6A is provided in a protruding manner and is secured to each bushing 14 in the axial direction. In addition, each pusher 16
Circular grooves 16B, 16B are provided at the center of the proximal end of the spool 13, and the head 13E of each spool 13 is inserted into each side groove 16B so as to be displaceable in the axial direction. Each pusher 16 is pressed by a swingable lever 17 to slide each spool 13 in the axial direction via each setting spring 20, which will be described later.

Reference numerals 18 and 18 denote spring receivers that are slidably inserted into each spring chamber 9, and the inner peripheral side of each spring receiver 18 is in contact with the proximal end surface of each pusher 16 and the lower surface of the head 13E of each spool 13. The pushers 16 are configured so that they can be axially displaced together with each pusher 16. When each pusher 16 is largely pressed in the axial direction, each spring bearing 18 is moved into each spring chamber 9.
The pushers 16 are brought into contact with the stepped portions 9A to restrict further displacement of each pusher 16. 19,1
Reference numeral 9 denotes a return spring for returning each pusher 16 to the illustrated position. Each return spring 19 is disposed within each spring chamber 9 and urges each pusher 16 upward in the axial direction via each spring receiver 18. ing.

Reference numerals 20 and 20 denote setting springs that press each spool 13 downward in the axial direction according to the amount of pressing operation of each pusher 16 and set the pressure in each output port 6 via each spool 13; 20 is located inside each return spring 19 in each spring chamber 9, and is disposed between each spring receiver 18 and the annular portion 13C of each spool 13. And each setting spring 2
0 slides and displaces each spool 13 downward in the axial direction when each pusher 16 is pressed by the lever 17, and the annular portion 13 of each spool 13 is
C and each sliding hole 8A, 8 through large diameter portion 13A.
Open and close B. On the other hand, when each spool 13 is pressed upward by the pressure within each pressure chamber 11, each setting spring 20 allows each spool 13 to slide upward in the axial direction, and each annular portion 13C and each sliding hole 8 through each large diameter portion 13A.
A and 8B are opened and closed. In this way, each setting spring 20 is bent by the pressure inside each pressure chamber 11, and while balancing the spring load at that time and the pressure inside each pressure chamber 11, each spool 13 is slid up and down. The pressure inside each output port 7 is set to a value corresponding to the swing angle of the lever 17, that is, the amount of pressing operation of each pusher 16.

Further, reference numerals 21 and 21 denote plugs as plugs screwed onto the lower end side of each pressure chamber 11, and each plug 2
1 closes the lower end side of each shaft hole 8 provided through the casing 1 in the axial direction to prevent the oil in each pressure chamber 11 from leaking to the outside. here,
Each of the plugs 21 is used to close each shaft hole 8 formed by a through hole at the other end in order to perform highly accurate hole machining in each of the sliding holes 8A, 8B, and 8C.

Next, the operation of the pressure reducing valve type pilot valve configured as described above will be explained.

First, when the lever 17 is in the neutral position as shown, each spool 13 closes each sliding hole 8B with its large diameter portion 13A and opens each sliding hole 8A with its annular portion 13C, so each output port 6 Spring chamber 9, passage 1
It is communicated with the tank port 5 through the port 0, is cut off from the pump port 3, and is placed in a low pressure state.

When the lever 17 is swung in the direction of arrow A, one of the pushers 16 is pressed downward in the axial direction, and one of the spools 13 is slidably displaced downward in the axial direction via the setting spring 20. When the sliding holes 8A and 8B are opened and closed by the annular portion 13C and the large diameter portion 13A of the spool 13, one output port 6 is blocked from the tank port 5 and communicated with the pump port 3. Therefore, the output port 6 and the pressure chamber 11 are at high pressure, and the spool 13 is pushed upward in the axial direction. As a result, the spool 13 is slid upward in the axial direction, and the setting spring 20
is compressed from its preset state and begins to bend. When the sliding holes 8A and 8B are opened and closed again by the annular portion 13C and large diameter portion 13A of the spool 13, the pressure in the output port 6 and the pressure chamber 11 decreases, so that the setting spring 20 The spring load causes the spool 13 to slide downward in the axial direction again, closing the sliding hole 8A and opening the sliding hole 8B.

Thus, the one spool 13 slides upward and downward, and while the sliding holes 8A and 8B are repeatedly opened and closed, the pressure in the output port 6 is set to a value corresponding to the amount of pressing operation of the one pusher 16. Set via spring 20. Then, when the amount of pressing operation of the pusher 16 is further increased and the head 13E of the spool 13 comes into contact with the bottom of the concave groove 16B of the pusher 16, the spool 13 is displaced integrally with the pusher 16. Therefore, the pressure inside the output port 6 is set to the same pressure as inside the pump port 3. Further, when the lever 17 is swung in the direction of arrow B, the other spool 13 is operated in the same manner as described above via the other pusher 16, and the pressure in the other output port 6 is adjusted to an appropriate value. Can be set.

[Problem that the invention attempts to solve]

However, in the prior art described above, each pressure chamber 11
Since each plug 21 is screwed onto the lower end side of the shaft hole 8 to individually close the lower end side of each shaft hole 8, a female thread is inserted at the lower end side of each shaft hole 8, that is, the lower end side of each pressure chamber 11. In addition, each plug 21 must be individually screwed in, which makes the plugging operation troublesome. Furthermore, oil may leak from around each plug 21, resulting in an increase in the number of oil leakage locations.

Furthermore, the lower end side of each shaft hole 8 and the pump port 3,
If the distance between the tank port 5 and the lower end side is small, piping work to the pump port 3 and tank port 5 and screwing work of each plug 21 may become difficult. The lower end side must be provided with a large distance outward from the lower end side of each shaft hole 8, which has the disadvantage that the outer shape of the casing 1 becomes large.

The present invention has been devised in view of the above-mentioned drawbacks of the prior art. It is an object of the present invention to provide a pressure reducing valve type pilot valve which can simplify screw processing and plugging work, reduce oil leakage points, and also reduce the outer size of the casing.

[Means for solving problems]

In order to solve the above-mentioned problem, the feature of the configuration adopted by the present invention is that a single unit is provided on one end side of the casing, spaced apart from a port opening on the end face of the one end side of the casing, and communicating with one end side of each shaft hole. The first concave groove,
A single plug is fitted into the groove and has its center portion fixed to one end of the casing to close one end of each of the shaft holes, and the plug and each spool are connected to each other. A plurality of pressure chambers are formed between the first end and the second end, respectively, and each of the pressure chambers communicates with each output port individually.

[Effect]

With the above configuration, there is no need to individually close one end side of each shaft hole, and each shaft hole can be closed simultaneously using a single plug. In addition, since the stopper is fixed to the casing at the center, the port opening at one end of the casing can be separated from the fixed part of the stopper by a large distance, making it easy to perform piping work to the port. can.

〔Example〕

Hereinafter, an embodiment of the present invention will be described based on FIG. In the embodiment, the same components as those of the prior art shown in FIG. 2 described above are given the same reference numerals, and their explanations will be omitted.

In the figure, 31 indicates a casing constituting the pilot valve body, and the casing 31 is provided with a pump port 3, a tank port 5, each output port 6, and each shaft hole 8, as in the casing 1 described in the prior art. It is being Spring chambers 9, 9 are provided on the upper end side of each shaft hole 8, and pressure chambers 11, 11 are provided on the lower end side between the lower end surface of the large diameter portion 13A of each spool 13 and a plug body 32, which will be described later. A sliding hole 8A, in which each spool 13 is slidably displaced in the axial direction, is provided between each spring chamber 9 and each pressure chamber 11, respectively.
8B and 8C are provided respectively. However,
In the casing 31, each pressure chamber 11 is provided at the center of the lower end side.
A large diameter groove 31A is provided so as to face the groove 31A, and a screw hole 31B into which a bolt 33 (to be described later) can be screwed is provided in the center of the bottom side of the groove 31A. The groove 31A communicates with the lower end of each shaft hole 8.

Reference numeral 32 denotes a plug that is fitted into the groove 31A and closes the lower end side of each shaft hole 8;
is formed into a substantially disk shape so as to be able to fit into the groove 31A, and a bolt insertion hole 32A is bored in the center. A bolt 33 screws the plug 32 into the groove 31A, and the bolt 33 is inserted into the screw hole 3 of the casing 31 through the bolt insertion hole 32A of the plug 32.
1B, and fixes the center portion of the stopper 32 to the lower end side of the casing 31. 34 is each pressure chamber 1
O-ring 35 prevents oil from leaking from one pressure chamber 11 to the other pressure chamber 11. The O-ring 35 is located between the top surface of the plug body 32 and the bottom surface of the groove 31A, and is disposed so as to surround the bolt 33.

The pressure reducing valve type pilot valve according to this embodiment has the above-mentioned configuration, and its operation is not particularly different from that of the prior art.

However, in this embodiment, a groove 31A communicating with each shaft hole 8 is provided at the center of the lower surface of the casing 31, and a plug 32 is fitted into the groove 31A.
Since the central part of the shaft hole 8 is fixed to the casing 31 with the bolt 33, the lower end side of each shaft hole 8 can be closed with a single plug body 32, which simplifies the plugging operation. Thread processing also screw hole 3
It can be set to only one location in 1B. and,
It is possible to reduce the number of oil leakage points, and in case of oil leakage, it can be easily dealt with by simply replacing the O-rings 34 and 35, and it is possible to prevent the number of sealing members such as O-rings from increasing. . In addition, the plug body 32 is different from each plug 21 used in the prior art.
Since there is no need to rotate the O-rings 34 and 35 when closing the cap, the possibility of damage to the O-rings 34 and 35 can be reliably reduced.

Further, in this embodiment, the bolt 33 is inserted into the bolt insertion hole 32A drilled in the center of the plug 32, and screwed into the screw hole 31B, so that the plug 32 is inserted into the groove 31A. Since it can be fixed and the lower end side of each shaft hole 8 can be closed, even if the lower end side of the pump port 3 or tank port 5 is placed as close as possible to the lower end side of each shaft hole 8, that is, the groove 31A, the pump Piping work to the port 3 and tank port 5 can be easily performed, and the outer shape of the casing 31 can be made small and compact.

In the above embodiment, the plug body 32 is connected to the bolt 33.
Although it has been described that the stopper 32 is fixed in the groove 31A by means of the bolt 33, the plug 32 may be fixed in the groove 31A using means other than the bolt 33.

Further, in the embodiment described above, the case where two shaft holes 8 are bored in the casing 31 has been described as an example, but the present invention is not limited to this.
or more, for example, four shaft holes 8, and each shaft hole 8
The four spools 13, which are slidably inserted into the spools 13, may be slidably displaced by the swinging operation of the lever 17, and, for example, two directional control valves may be switched and controlled, respectively. In this case, the four shaft holes 8 can be plugged with a single plug 32.

[Effect of idea]

As described in detail above, according to the present invention, on one end side of the casing, there is a single groove spaced apart from the port opening on the end face of the one end side of the casing and communicating with one end side of each shaft hole; a single stopper that is fitted into the groove and whose center portion is fixed to one end of the casing to close one end of each of the shaft holes; the stopper and one end of each spool; Since a plurality of pressure chambers that communicate with each output port individually are formed between the shaft holes, there is no need to individually plug each shaft hole as in the prior art, and the plugging operation can be simplified. Further, it is not necessary to perform thread processing on each shaft hole, and the number of man-hours for thread processing can be reduced, and it is also possible to reduce oil leakage points. Furthermore, since each shaft hole can be plugged together with a plug body, piping work etc. can be easily performed even if the pump port, tank port, etc. are placed as close as possible to each shaft hole. It becomes possible to reduce the external size and form it compactly.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a pilot valve according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing a pilot valve according to the prior art. 3...Pump port, 5...Tank port, 6
...Output port, 8...Shaft hole, 9...Spring chamber, 1
1... Pressure chamber, 13... Spool, 16... Pusher, 20... Setting spring, 31... Casing,
31A...concave groove, 31B...screw hole, 32...plug body, 33...bolt.

Claims (1)

[Scope of utility model registration request] a casing having a pump port, a tank port, and a plurality of output ports, at least two of which are open at one end surface;
A plurality of shaft holes are provided to penetrate the casing in the axial direction and communicate with the pump port and each output port, and a plurality of shaft holes are slidably inserted into each of the shaft holes, and each of the output ports is connected to the pump port. It consists of a plurality of spools that selectively communicate with the tank port, and a plurality of pushers located on the other end side of each spool and provided on the casing to slide each spool in the axial direction. In the pressure reducing type pilot valve, a single groove is provided on one end of the casing and is spaced apart from the port opening on the end surface of the one end of the casing and communicates with one end of each of the shaft holes; a single plug that is fitted into the casing and whose center portion is fixed to one end of the casing to close one end of each of the shaft holes; A pressure reducing valve-type pilot valve, characterized in that a plurality of pressure chambers are formed between the two, each of which communicates separately with each of the output ports.