JP2020101278A - Control valve - Google Patents

Abstract

To configure a control valve that properly controls a flow of a working fluid through a communication hole of a cylindrical portion of a spool even if oil amounts are increased.SOLUTION: A rising control spool 14 is configured, which has a cylindrical second land part 14b around a first axis X1, and is formed with a plurality of communication holes 17 that have penetration hole shape for communicating an interior space and an exterior space of the second land part 14b and have different inner diameters. When the rising control spool 14 is set at a block position, a flow of a working fluid from a pump port 12 to a discharge port 13 is intercepted, and when the rising control spool 14 is set at a supply position, the working fluid from the pump port flows from a part of the plurality of communication holes 17 to the interior space of the second land part 14b, and is sent out from a part of the other communication holes to the discharge port 13.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control valve that sends hydraulic oil from a pump port to a discharge port by operating a spool inside a valve housing.

As a control valve configured as described above, in Patent Document 1, an unload valve and a switching valve are housed in a valve hole formed in a valve body, and the pressure acting on the unload valve is controlled by the operation of the switching valve. , A technique of operating an unload valve by hydraulic pressure and controlling the amount of hydraulic oil discharged by the unload valve is disclosed.

In the control valve (unloading device in the literature) having this configuration, the unload valve is provided with a tubular portion, and the tubular portion is formed with a plurality of first ports and a plurality of second ports. The valve body is provided with an inlet port to which hydraulic oil is supplied from a hydraulic pump and a tank port, and the tubular portion of the unload valve is arranged in the region extending over these ports.

As a result, when the unload valve operates, hydraulic oil from the inlet port flows from the first port into the inside of the tubular portion, and the tank port is sent out from the second port to realize unloading.

JP-A-7-174102

The unloading valve (spool) described in Patent Document 1 has a configuration in which a plurality of communication holes penetrating the tubular portion and communicating the inside and the outside are formed so as to be arranged along the circumferential direction of the tubular portion. ing. Therefore, depending on the stroke position of the unload valve (positional relationship between the tank port and the second port), the fluid force of the hydraulic oil acts in the axial direction of the spool, and it may not be possible to flow the desired amount of hydraulic oil. Yes, the effect becomes more remarkable as the flow rate of hydraulic oil increases.

For these reasons, there is a demand for a control valve that can appropriately control the flow rate of hydraulic oil that flows through the communication hole of the tubular portion of the spool even when the amount of oil increases.

A characteristic configuration of a control valve according to the present invention is a valve housing having a spool chamber which is coaxial with an operating shaft core, a pump port to which hydraulic oil is supplied and a discharge port for sending out hydraulic oil, and a closed position. A spool housed in the spool chamber so as to be operable between a spool and a supply position, the spool having a tubular portion centered on a spool shaft core, and the inside of the tubular portion. When a plurality of communication holes having different opening areas and communicating the space with the external space are provided and the spool is set to the closed position, the hydraulic oil from the pump port to the discharge port When the flow is shut off and the spool is set to the supply position, the hydraulic oil from the pump port flows from a part of the plurality of communication holes into the internal space of the spool, and the other communication is performed. It is at a point where it is delivered to the discharge port from a part of the hole.

According to this characteristic configuration, when the spool is in the closed position, the flow of the hydraulic oil in the plurality of communication holes is blocked, and when the spool is set in the supply position, the hydraulic oil from the pump port is not The hydraulic oil flows from the communication hole into the internal space of the tubular portion of the spool, and the hydraulic oil is sent out to the discharge port through a communication hole different from the one into which the hydraulic oil flows. At this time, the outflow angle of the hydraulic oil flowing out from each communication hole is close to the angle perpendicular to the axial center of the spool, so that the fluid force in the axial direction is suppressed from acting on the spool and the flow rate of the operating oil is reduced. The flow rate of the hydraulic oil can be appropriately controlled even when is increased.

As another configuration, the spool chamber is provided with a spool hole for accommodating the tubular portion of the spool in the middle of the pump port and the discharge port, and when the spool is in the supply position, a plurality of the spool holes are provided. When a part of the communication hole communicates with the discharge port and a part of the other communication hole communicates with the pump port, and the spool operates from the supply position to the closed position, the supply position The positional relationship among the plurality of communication holes may be set so that the communication hole that is present is closed by the spool hole.

According to this, by operating the spool along the spool shaft core, it is possible to switch between a state in which the working oil is shut off and a state in which the working oil can be supplied.

As another configuration, any of the plurality of communication holes may be exposed when viewed from any direction orthogonal to the spool axis.

According to this, the plurality of communication holes are arranged in a positional relationship of being close to each other in the circumferential direction, and as a result, the flow rate of the hydraulic oil in the plurality of communication holes can be increased.

As another configuration, the plurality of communication holes may be formed in a posture orthogonal to the spool shaft core.

According to this, in each of the plurality of communication holes, the fluid flows in the direction orthogonal to the cylindrical portion, so that not only the distance that the hydraulic oil contacts the inner peripheral wall of the communication hole is shortened, but also the communication hole is formed. It reduces the resistance when hydraulic oil comes into contact with the inner peripheral wall of the. Therefore, the fluid force acting on the spool can be reduced and the flow rate of the hydraulic oil can be appropriately controlled even when the flow rate of the hydraulic oil increases.

As another configuration, a plurality of communication holes having different opening areas may be arranged along the circumferential direction of the tubular portion.

According to this, even when the flow rate of the hydraulic oil is increased, the hydraulic oil can be appropriately circulated.

As another configuration, a plurality of the communication holes having substantially the same opening area, a part of the communication holes overlap each other along the circumferential direction of the tubular portion, and the center position of the communication holes is the same. It may be arranged at a position offset in the axial direction of the tubular portion.

According to this, even when the flow rate of the hydraulic oil is increased, the hydraulic oil can be appropriately circulated.

As another configuration, an outer peripheral passage having a diameter smaller than the inner diameter of the spool chamber in which the cylindrical portion is housed is formed on the outer periphery of the cylindrical portion, and the outer peripheral passage is in a direction along the spool shaft core. When the spool is set to the closed position, the flow of hydraulic oil from the pump port to the discharge port is blocked, and when the spool is set to the supply position, It may be formed in a region for sending hydraulic oil to the discharge port.

According to this, when the spool is set to the closed position, the hydraulic oil from any of the outer peripheral flow path and the plurality of communication holes is not supplied to the discharge port. On the other hand, when the spool is set to the supply position, hydraulic oil from the pump port is supplied to the discharge port via the outer peripheral flow path, and hydraulic oil from the pump port is discharged via the multiple communication holes. Since the oil is supplied to the port, the flow rate of the hydraulic oil supplied from the pump port to the discharge port is increased.

As another configuration, the discharge side end portion of the outer peripheral flow path, which is arranged on the discharge port side, may have a tapered surface having a smaller diameter at a position further away from the discharge port.

According to this, when the discharge side end reaches the position communicating with the discharge port as the spool moves from the closed position to the supply position, the outer peripheral flow path increases as the operation amount of the spool increases thereafter. The flow rate of the hydraulic oil supplied to the discharge port via the is increased, and a rapid increase in the oil amount can be suppressed.

It is a hydraulic circuit diagram of a valve unit. FIG. 8 is a cross-sectional view of the lift control valve in the closed position. It is sectional drawing of the raising control valve in a supply position. It is sectional drawing of a raising control spool. It is an expanded sectional view of a part of a communication hole of a rise control valve in an open position. FIG. 6 is a cross-sectional view of the lowering control valve in the closed position. It is a sectional view of a descending control valve in a discharge position. It is sectional drawing of an electromagnetic valve. It is sectional drawing which shows the female screw part and the male screw part of a separated state. It is sectional drawing in the closed position of the raising control valve of another embodiment (d). It is sectional drawing in the supply position of the raising control valve of another embodiment (d). It is sectional drawing which shows the outer peripheral flow path of another embodiment (d). It is a graph which shows the relationship between the operation amount of the raising control valve and the flow rate of hydraulic oil of another embodiment (d).

Embodiments of the present invention will be described below with reference to the drawings.
〔overall structure〕
As shown in FIG. 1, a hydraulic oil supply port Hp to which hydraulic oil from a hydraulic pump P is supplied, a cylinder port Hc connected to a lift cylinder C, and a plurality of discharge ports Hd for discharging hydraulic oil are provided in a valve housing H. A valve unit A is configured by including a pressure compensation valve Vr, a rising control valve Vu, a rising side electromagnetic valve Vuc, a falling control valve Vd, and a falling side electromagnetic valve Vdc in the valve housing H. There is.

The valve unit A is shown as being provided in the vehicle body of the tractor. The hydraulic pump P is driven by an engine (not shown), and the lift cylinder C drives the lift arm 1 provided at the rear end of the vehicle body.

In this valve unit A, a main flow path 2 for supplying the hydraulic oil from the hydraulic pump P is formed in the valve housing H, and is branched from the main flow path 2 so as to compensate the pressure of the hydraulic oil flowing in the main flow path 2. The pressure control flow path 3 is provided with a pressure compensation valve Vr. Further, a rising control valve Vu is arranged so as to open and close the hydraulic oil flowing in the main flow path 2, and a descending control valve Vd is arranged in a branch flow path 4 branching from the main flow path 2.

The rising control valve Vu is operated by the pilot pressure controlled by the rising electromagnetic valve Vuc, and the rising control pilot passage 5 is formed between the rising control valve Vu and the rising electromagnetic valve Vuc.

Similarly, the descending control valve Vd is operated by the pilot pressure controlled by the descending side electromagnetic valve Vdc, and the descending control pilot passage 6 is formed between the descending control valve Vd and the descending side electromagnetic valve Vdc. ..

The pressure compensating valve Vr has a compensating function of maintaining the pressure of the hydraulic oil supplied from the hydraulic oil supply port Hp at a set value regardless of the load acting on the lift cylinder C. The ascending-side electromagnetic valve Vuc generates a pilot pressure corresponding to the supplied current value, and causes the generated pilot pressure to act on the ascending control pilot passage 5. Further, the descending electromagnetic valve Vdc generates a pilot pressure corresponding to the supplied current value and causes the generated pilot pressure to act on the descending control pilot passage 6.

A working device such as a rotary tiller and a plow is supported by the lift arm 1 in a suspended state, and a vehicle body is provided with a control device (not shown) for controlling the lifting of the working device. This control device acquires information such as the ground height of the work device or the towing load acting on the work device, sets the target posture of the lift arm 1, and raises the electromagnetic valve Vuc on the rising side so as to reach this target posture. And an elevating control for controlling the descending side electromagnetic valve Vdc are realized.

[Rise control valve]
As shown in FIGS. 2 to 4, an ascending side spool chamber 11 is formed coaxially with the first axis X1 (an example of an operating axis) with respect to the valve housing H, and the ascending side spool chamber 11 has a pump port. 12 and the discharge port 13 are formed in a communicating state. The rising control valve Vu is configured such that the rising control spool 14 and the rising spring 15 are housed in the rising spool chamber 11.

The pump port 12 is formed at a position in the main flow path 2 to which the hydraulic oil is supplied from the hydraulic oil supply port Hp, and the discharge port 13 is formed at a position in the main flow path 2 that communicates with the cylinder port Hc. There is.

The rising control valve Vu has a structure in which the rising spool chamber 11 has a first spool hole 11a, a second spool hole 11b, and a third spool hole 11c arranged in this order along the first axis X1. The first spool hole 11a, the second spool hole 11b, and the third spool hole 11c are formed to have a circular cross-sectional shape centered on the first axis X1 (operating axis) and having the same inner diameter. ..

The first spool hole 11a is adjacent to a space in which the rising spring 15 is arranged, and the rising pressure receiving space 16 is adjacent to a position adjacent to the third spool hole 11c. The discharge port 13 is arranged between the first spool hole 11a and the second spool hole 11b, and the pump port 12 is arranged between the second spool hole 11b and the third spool hole 11c.

The rising control spool 14 is formed with a first land portion 14a which is fitted in the first spool hole 11a and a second land portion 14b which is fitted in the second spool hole 11b to the third spool hole 11c. At the same time, an ascending side plunger 14c having the same diameter as the second land portion 14b is integrally formed at a position continuous with the second land portion 14b.

The raising control spool 14 has a columnar shape as a whole with a spool shaft core (not shown) as a center, and the spool shaft core corresponds to the first shaft core X1 in a state where the rising control spool 14 is inserted in the rising side spool chamber 11. Match. The second land portion 14b described above is formed in a tubular shape around the spool shaft center (which coincides with the first shaft center X1). The second land portion 14b is formed to have a predetermined thickness, and a plurality of through holes 17 having a plurality of through holes and having different opening areas are formed in the second land portion 14b so as to connect the internal space and the external space. .. Each of the plurality of communication holes 17 is formed in a posture orthogonal to the first axis X1. In this way, the portion of the second land portion 14b formed in the tubular shape becomes the tubular portion.

That is, as the communication holes 17, three types having different opening diameters (different opening areas) are used, and the large diameter communication holes 17 are arranged side by side along the circumferential direction of the second land portion 14b. By arranging the small-diameter communication holes 17 between the large-diameter communication holes 17 arranged in parallel, the cross-sectional area of the opening through which the hydraulic oil can flow is increased.

Further, it is formed in such a positional relationship that any opening of the plurality of communication holes 17 is exposed when viewed from any direction orthogonal to the first axis X1.

In this rising control valve Vu, when the pilot pressure does not act on the rising pressure receiving space 16 from the rising electromagnetic valve Vuc, the rising control spool 14 is maintained in the closed position shown in FIG. 2 by the urging force of the rising spring 15. It Further, when the pilot pressure acts on the rising side pressure receiving space 16 from the rising side electromagnetic valve Vuc, the rising control spool 14 moves to a position where the urging force of the rising side spring 15 and the pilot pressure are balanced as shown in FIG. Operates and reaches supply position.

When the raising control spool 14 is in the closed position, a part of the plurality of communication holes 17 communicates with the pump port 12, but the plurality of communication holes 17 are closed by the second spool hole 11b, and the discharge port is closed. 13 is maintained in a state not communicating.

On the other hand, when the raising control spool 14 reaches the supply position, a part of the plurality of communication holes 17 communicates with the discharge port 13, and the remaining part of the plurality of communication holes 17 does the pump port. 12 is in communication. As a result, the hydraulic oil from the pump port 12 flows from the communication hole 17 into the internal space of the second land portion 14b, and the hydraulic oil in the internal space further flows from the communication hole 17 to the external space and is supplied to the discharge port 13.

In particular, the supply position refers to a plurality of positions included in the region for sending the hydraulic oil from the pump port 12 to the discharge port 13, and the situation where the pilot pressure acting from the ascending side electromagnetic valve Vuc has increased in the supply position. In the position (1), the supply amount of hydraulic oil increases compared to the position in which the pilot pressure is low.

In this rise control valve Vu, when the current driving the rise side electromagnetic valve Vuc is increased, the operation amount of the rise control spool 14 is also increased corresponding to the increase in the drive current. Therefore, in a situation where the raising control spool 14 is in the supply position, the amount of hydraulic oil supplied from the cylinder port Hc to the lift cylinder C is increased in response to an increase in the drive current, so that the lift arm 1 can be raised at high speed. Realized.

In particular, as shown in FIG. 5, since the plurality of communication holes 17 are formed in the posture orthogonal to the first axis X1, the flow passage resistance when the working oil flows through the communication holes 17 is small, and the rise control valve Vu is small. It is possible to increase the amount of hydraulic oil supplied from the cylinder port to the cylinder port Hc. That is, in the present embodiment, the plurality of communication holes 17 having different opening areas are formed in the direction substantially perpendicular to the first axis X1. The hydraulic oil flowing out from these communication holes 17 has an outflow angle close to a vertical angle with respect to the first axis X1, so that the fluid force acting on the lift control spool 14 can be reduced. As a result, it is possible to suppress the fluid force of the hydraulic oil from acting in the direction of closing the rising control spool 14, and it is possible to appropriately control the flow rate of the hydraulic oil even when the flow rate of the hydraulic oil increases.

[Descent control valve]
As shown in FIGS. 6 and 7, the lowering control valve Vd includes a pressure port 22 and a first drain port 23 in a descending spool chamber 21 formed in the valve housing H coaxially with the second axis X2. , The second drain port 24 are formed in this order along the second axis X2, and the descending spool chamber 21 accommodates the descending control spool 25 and the descending spring 26. There is.

The pressure port 22 communicates with the cylinder port Hc, and the first drain port 23 and the second drain port 24 each communicate with the discharge port Hd.

The descending spool chamber 21 has a guide hole 21a, an abutting portion 21b, a control hole 21c, and a plunger hole 21d formed in this order along the second axis X2.

In this descending control valve Vd, the pressure port 22 communicates with the space between the control hole 21c and the plunger hole 21d. Further, the space between the contact portion 21b and the guide hole portion 21a communicates with the first drain port 23, and the space on the outer end side of the guide hole portion 21a (the space where the descending side spring 26 is arranged) is the second. It communicates with the drain port 24. The first drain port 23 and the second drain port 24 are individually communicated with the branch flow passage 4.

Further, the second drain port 24 communicates with the guide hole 21a. The lowering control pilot channel 6 communicates with the outer end position of the plunger hole 21d.

The lowering control spool 25 is formed with a regulation wall portion 25a accommodated in the guide hole portion 21a, an abutment land portion 25b abutting against the abutment portion 21b, and a control land portion 25c accommodated in the control hole portion 21c. ing. Further, on the outer periphery of the control land portion 25c, an auxiliary flow passage 25cg is formed that allows the flow of hydraulic oil in a groove shape from the intermediate position in the operating direction of the lowering control spool 25 toward the lower plunger 25d. .. Further, a descending side plunger 25d having the same diameter as the control land portion 25c is formed at a position continuous with the control land portion 25c.

In this lowering control valve Vd, the contact land portion 25b contacts the contact portion 21b by the urging force of the lower spring 26, so that the lowering control spool 25 is maintained in the closed position shown in FIG. In this closed position, the pressure port 22 is kept closed. The regulation wall portion 25a is also configured as a spring receiving member that receives the urging force of the descending side spring 26.

In addition, the dimensional relationship is set so that the outer circumference of the restriction wall portion 25a and the inner circumference of the guide hole portion 21a are close to each other. That is, the guide hole portion 21a has an inner peripheral surface of a cylinder centered on the second axis X2, and the outer periphery of the restriction wall portion 25a is close to this inner peripheral surface. A small phenomenon that hydraulic oil from the pressure port 22 flows to the second drain port 24 when the lowering control spool 25 operates is suppressed.

When the descending electromagnetic valve Vdc is driven and the pilot pressure acts on the descending control pilot passage 6, the descending control spool 25 operates to a position where the urging force of the descending spring 26 and the pilot pressure are balanced, The discharge position shown in 7 is reached.

Particularly, the discharge position refers to a plurality of positions included in a region in which the hydraulic oil from the pressure port 22 flows to the first drain port 23, and in the discharge position, the pilot pressure acting from the descending electromagnetic valve Vdc is At the discharge position when rising, the discharge amount of hydraulic oil increases compared to the position where the pilot pressure is low.

As described above, in the discharge position shown in FIG. 7 from the closed position, the contact land portion 25b is separated from the contact portion 21b, and the pressure port 22 is provided via the auxiliary flow path 25cg of the control land portion 25c. From the first hydraulic fluid flows to the first drain port 23.

Further, when the lowering control spool 25 moves to the discharge position, the hydraulic oil in the space in which the lowering side spring 26 is arranged is discharged from the second drain port 24 with the displacement of the restriction wall portion 25a. Particularly, when the lowering control spool 25 is set to the discharge position, the regulating wall portion 25a moves with the movement of the lowering side plunger 25d, but the regulating wall portion 25a is located inside the guide hole portion 21a. The phenomenon in which the hydraulic oil from the pressure port 22 flows to the second drain port 24 is suppressed.

Then, when the drive current of the descending electromagnetic valve Vdc is increased, the operation amount of the descending control spool 25 is also increased corresponding to the increase of the drive current. Therefore, when the lowering control spool 25 is in the discharge position, the amount of hydraulic oil discharged from the pressure port 22 through the first drain port 23 is increased in response to an increase in the drive current, and the lift arm 1 is lowered. Achieve higher speed.

Particularly, in this lowering control valve Vd, the contact land portion 25b has a relatively simple structure including the contact portion 21b, but the hydraulic oil from the pressure port 22 is discharged from the first drain port 23. Thus, it is possible to prevent the working oil from being accumulated in the space (spring chamber) in which the descending side spring 26 is arranged. As a result, even if the pressure of the hydraulic oil acting on the cylinder port Hc is high, the pressure in the space (spring chamber) in which the descending spring 26 is arranged rises (the pressure in the spring chamber causes a muffled pressure) to close the through hole. It is possible to suppress the directional force from acting on the lowering control spool 25 and reliably discharge the hydraulic oil even when the flow rate of the hydraulic oil is large.

(Electromagnetic valve)
In this valve unit A, the one having a configuration common to the ascending side electromagnetic valve Vuc and the descending side electromagnetic valve Vdc is used. For this reason, common parts of the ascending-side electromagnetic valve Vuc and the descending-side electromagnetic valve Vdc will be described with common reference numerals.

As shown in FIG. 8, an electromagnetic valve (a higher-order concept of an ascending-side electromagnetic valve Vuc and a descending-side electromagnetic valve Vdc) is a bottomed cylindrical first housing 31 made of a magnetic material, and an opening of the first housing 31. A second housing 32 screw-connected to the first housing 31, a plunger body 33 made of a magnetic material housed in the first housing 31, a coil portion 34 for generating magnetism acting on the plunger body 33, and a valve for controlling pilot pressure. And a unit 35.

In this electromagnetic valve, the first housing 31 and the second housing 32 function as a yoke that causes the magnetic flux from the coil portion 34 to act on the plunger body 33. The coil portion 34 has a structure in which a conductor wire made of a conductor is wound around a bobbin, and is configured to increase the magnetic force acting on the plunger body 33 as the current supplied to the conductor wire increases. ing.

In the first housing 31, an end wall 31b in a posture orthogonal to the third axis X3 is integrally formed on the outer end of a cylindrical wall 31a centered on the third axis X3, and as shown in FIG. A female screw portion 31S is formed on the inner periphery of the opening of the shaped wall 31a.

The second housing 32 sandwiches a shaft-shaped portion 32a housed in the internal space of the cylindrical wall 31a of the first housing 31, a large-diameter portion 32b having a larger diameter than the shaft-shaped portion 32a, and a large-diameter portion 32b. Thus, the shaft-shaped portion 32a and the protruding shaft portion 32c that protrudes to the opposite side are integrally formed. The electromagnetic valve is connected and fixed to the outer surface of the valve housing H with the protruding shaft portion 32c fitted in the hole of the valve housing H.

As shown in FIG. 9, a male screw portion 32S is formed on the outer circumference of the large-diameter portion 32b of the second housing 32, and the male screw portion 32S is screwed onto the female screw portion 31S of the first housing 31 to form the first screw thread. The housing 31 and the second housing 32 are in a connected state.

With the second housing 32 screw-connected to the first housing 31, the centers of the shaft-shaped portion 32a, the large-diameter portion 32b, and the protruding shaft portion 32c of the second housing 32 are aligned with the third axis X3. It is placed at the matching position. The screw connection structure will be described later.

The plunger body 33 is housed in the inner space of the first housing 31 in the vicinity of the end wall 31b so as to be movable in the direction along the third axis X3. An insertion hole 32d is formed in the shaft-shaped portion 32a of the second housing 32 so as to be coaxial with the third shaft core X3. The plunger body 33 has a rod 33a that operates integrally, and the rod 33a is arranged in a state of being inserted into the insertion hole 32d.

In this electromagnetic valve (upward electromagnetic valve Vuc, downward electromagnetic valve Vdc), the magnetic flux generated when the coil portion 34 is driven flows through the magnetic path formed in the first housing 31 and the second housing 32. When the magnetic path is formed in this way, the male screw portion 32S and the female screw portion 31S of the first housing 31 are threadedly connected to the outer circumference of the large diameter portion 32b of the second housing 32 to increase the magnetic resistance. It has a structure that does not allow it.

As shown in FIG. 9, of the female screw portion 31S formed in the first housing 31, the inner end position (the right side in the figure) where the protruding end of the male screw portion 32S is screwed is directed inward. Thus, a pressure receiving surface 31T having a posture orthogonal to the third axis X3 is formed. Further, a contact surface 32T having a posture orthogonal to the third axis X3 is formed at the protruding end of the male screw portion 32S formed on the shaft-shaped portion 32a of the second housing 32. The contact surface 32T is formed as a boundary wall in a posture orthogonal to the axis X at the boundary between the shaft-shaped portion 32a and the large diameter portion 32b.

Further, in the female screw portion 31S, an annular groove portion 31G is formed by removing the entire circumference of the inner end side portion where the protruding end portion of the male screw portion 32S is screwed in the direction along the third axis X3. .. This annular groove portion 31G is originally a region where an incomplete thread portion is formed, and by forming the annular groove portion 31G in this manner, it is appropriate when the male screw portion 32S is screwed into the female screw portion 31S. It realizes the screwing. By performing proper screwing in this manner, the pressure receiving surface 31T and the contact surface 32T are reliably brought into close contact with each other, and the space between the cylindrical wall 31a of the first housing 31 and the large diameter portion 32b of the second housing 32 is made. Suppresses an increase in the magnetic resistance of the magnetic path.

The valve unit 35 includes a spool body 35a that is operated in association with the operation of the plunger body 33 when the outer end portion of a rod 33a that operates integrally with the plunger body 33 contacts, and a slide operation of the spool body 35a. And a control bush 35b which is freely accommodated.

The control bush 35b has a flow path for supplying the hydraulic oil from the hydraulic oil supply port Hp and a flow path for discharging the hydraulic oil to the discharge port Hd, and the spool body 35a has a pilot flow path (a rising control pilot flow). By connecting the passage 5 and the descending control pilot passage 6) to the discharge port Hd, the pressure of the pilot passages 5 and 6 is greatly reduced, and the pressure of the operating oil from the operating oil supply port Hp is set to the pilot passage 5. , 6 can be switched between the positions to be acted on.

Further, by increasing the current that drives the electromagnetic valve (upward electromagnetic valve Vuc, downward electromagnetic valve Vdc) coil portion 34, it is possible to apply a pilot pressure corresponding to the current to the pilot flow paths 5 and 6. Become.

As a result, by increasing the drive current of the ascending side electromagnetic valve Vuc, the pilot pressure in the ascending control pilot passage 5 is increased, and the ascending control spool 14 is largely operated. As a result, the flow rate of the hydraulic oil supplied to the lift cylinder C is increased. Allows for growth.

Further, by increasing the drive current of the descending electromagnetic valve Vdc, the pilot pressure in the descending control pilot passage 6 is increased, and the descending control spool 25 is largely operated. As a result, the amount of hydraulic oil discharged from the lift cylinder C is increased. It enables the increase of

[Operation and effect of the embodiment]
With this configuration, when the raising control spool 14 of the raising control valve Vu reaches the supply position, the hydraulic oil from the pump port 12 is discharged through the plurality of communication holes 17 formed in the second land portion 14b. Although it will be supplied to the port 13, since the communication hole 17 forms a large opening for circulation on the outer peripheral surface of the second land portion 14b, it is possible to supply a large amount of hydraulic oil and Since the communication hole 17 is formed in a posture orthogonal to the first axis X1, the hydraulic oil does not exert a resistance when the hydraulic oil flows through the communication hole 17, a smooth flow is realized, and pressure loss is suppressed. To do.

Although the descending electromagnetic valve Vdc has a relatively simple structure, such as blocking the flow of hydraulic oil by bringing the contact land portion 25b of the descending control spool 25 into contact with the contact portion 21b, the pressure solenoid valve Vdc The restriction wall portion 25a is provided for suppressing the inconvenience that the hydraulic oil flows into the second drain port 24. Therefore, for example, as compared with a control valve in which the hydraulic oil from the pressure port 22 is discharged through a space (spring chamber) in which the descending side spring 26 is arranged, the muffled pressure of the spring chamber is reduced by the descending control spool 25. It is possible to eliminate the disadvantage that the flow rate of hydraulic oil decreases due to

The ascending-side electromagnetic valve Vuc and the descending-side electromagnetic valve Vdc have a common configuration, and in each electromagnetic valve, a first housing 31 made of a magnetic material and a second housing 32 made of a magnetic material are screw-connected. It is configured to be integrated by.

Particularly, in this electromagnetic valve, a male screw portion 32S formed on the outer periphery of the large diameter portion 32b of the second housing 32 is opposed to a female screw portion 31S on the inner periphery of the opening portion of the tubular wall 31a of the first housing 31. It is a configuration in which is screwed. In this structure, by forming the annular groove portion 31G from which the entire circumference of the inner end side portion of the female screw portion 31S is removed, the pressure receiving surface 31T of the first housing 31 and the contact surface 32T of the second housing 32 are securely formed. To suppress the increase of the magnetic resistance at this part.

[Another embodiment]
The present invention may be configured as follows in addition to the above-described embodiments (those having the same functions as those in the embodiments have the same numbers and reference numerals as those in the embodiments).

(A) In the embodiment, three types of communication holes 17 having different opening diameters are shown, but instead of this, four or more types of communication holes 17 having different opening diameters are provided in the second land portion 14b (cylindrical portion). Form. With this configuration, the total cross-sectional area of the communication hole 17 formed in the second land portion 14b is increased, and the operating oil flows between the internal space and the external space of the second land portion 14b. To further increase the flow rate of

(B) The shape of the opening of the communication hole 17 is not limited to a circular shape, but may be an elliptical shape, a rectangular shape, or a triangular shape. In particular, by using a plurality of types of communication holes 17 having different opening shapes and different opening areas as described above, the hydraulic oil flows between the internal space and the external space of the second land portion 14b (cylindrical portion). A further increase in the flow rate of hydraulic oil is realized.

(C) In the embodiment, the rising control valve Vu for supplying the working oil to the lift cylinder C is used, but instead of this, it is also possible to use it as a control valve for discharging the working oil. As a specific configuration, it is conceivable to use the control valve of this configuration as the lowering control valve Vd of the embodiment.

(D) As shown in FIGS. 10 to 12, the inner diameter of the ascending-side spool chamber 11 in which the second land portion 14b is housed is larger than the outer circumference of the second land portion 14b, which is the tubular portion of the raising control spool 14. The outer peripheral flow path 18 is formed to have a smaller diameter. That is, the outer peripheral flow path 18 is formed by the gap G between the outer periphery of the second land portion 14b and the inner periphery of the second spool hole 11b of the ascending side spool chamber 11.

In this way, by reducing the entire diameter of the outer circumference of the middle portion of the second land portion 14b in the direction along the first axis X1, the position of the second land portion 14b close to the discharge port 13 (FIG. An outer peripheral flow path 18 is formed in a region extending from the discharge side end portion 18a (left side in FIGS. 10 to 12) to the supply side end portion 18b in the direction of the pump port 12. The discharge side end portion 18a is arranged at a position overlapping the region where the plurality of communication holes 17 are formed, and the outer peripheral flow path 18 has a tapered surface whose diameter becomes smaller toward the position closer to the pump port 12 than the discharge side end portion 18a. It has 18t.

The outer peripheral flow passage 18 blocks the flow of hydraulic oil from the pump port 12 to the discharge port 13 when the raising control spool 14 is set to the closed position shown in FIG. 10, and the raising control spool 14 is shown in FIG. 11. When set to the supply position, the hydraulic oil from the pump port 12 is sent to the discharge port 13.

With this configuration, in another embodiment (d), when the raising control spool 14 operates from the closed position shown in FIG. 10 to the supply position shown in FIG. 11, first, the pump is passed through a part of the communication hole 17 The supply of hydraulic oil from the port 12 to the discharge port 13 is started, and after the discharge side end portion 18a is operated to a position communicating with the discharge port 13, the hydraulic oil to the discharge port 13 is passed through the outer peripheral flow path 18. Is started to be supplied.

As described above, since the tapered surface 18t is formed at a position continuous with the discharge side end 18a, the taper surface 18t is supplied to the discharge port 13 via the outer peripheral flow path 18 as the operation amount of the lift control spool 14 increases. Since the flow rate of the hydraulic oil is gradually increased, it is possible to suppress a rapid increase in the oil amount. When the operation amount of the raising control spool 14 is increased, the amount of the hydraulic oil supplied from the pump port 12 to the discharge port 13 through the plurality of communication holes 17 is also increased, so that the discharge port 13 is discharged. An increase in the flow rate of supplied hydraulic oil is realized.

FIG. 13 shows the relationship between the operation amount (stroke) of the rising control spool 14 and the flow rate of the hydraulic oil supplied to the discharge port 13. As described in the embodiment, the graph shown as the first characteristic j in the figure is a characteristic associated with the operation of the rising control spool 14 in which the plurality of communication holes 17 are formed without forming the outer peripheral flow path 18. Further, the graph shown as the second characteristic k in the same figure is a characteristic associated with the operation of the rising control spool 14 in which the outer peripheral flow path 18 and the plurality of communication holes 17 are formed.

Further, the same figure shows the operating position m of the rising control spool 14 when the maximum flow rate is reached. As described above, in the other embodiment (d), when the raising control spool 14 reaches the operating position m, the raising control spool 14 is operated by the same amount, but compared with the first characteristic j. The increase in the amount of hydraulic oil supplied with the two characteristics k is realized.

As shown in FIGS. 10 to 12, notches are formed by notching both ends of the inner circumference of the second spool hole 11b of the ascending side spool chamber 11 in the direction along the first axis X1 over the entire circumference. The portion 11bx is formed. As a result, the amount of hydraulic oil is increased.

In this other embodiment (d), a plurality of communication holes 17 are formed in the rising control spool 14, and hydraulic oil is supplied through the plurality of communication holes 17 in a direction orthogonal to the first axis X1, When the raising control spool 14 is operated to the supply position shown in FIG. 11, the fluid force acting on the raising control spool 14 along the first axis X1 is suppressed. Further, since the outer peripheral flow path 18 is formed, it becomes possible to supply the hydraulic oil to the discharge port 13 via the outer peripheral flow path 18 without impairing a good surface for suppressing the fluid force. The amount of hydraulic oil supplied from the port 12 to the discharge port 13 is increased.

The position of the discharge side end portion 18a in another embodiment (d) can be set arbitrarily. For example, of the plurality of communication holes 17, the discharge port 13 is closest to the discharge port 13 but is closer to the discharge port than the discharge port. It may be formed at a position displaced in the direction of 13. By setting the position of the discharge side end 18a in this way, it is possible to accelerate the timing of increasing the amount of hydraulic oil when the raising control spool 14 is operated toward the supply position.

The configuration of the other embodiment (d) is not limited to the control valve that supplies the working oil to the lift cylinder C of the tractor, but can be applied to the one that controls the supply and discharge of the working oil to various working devices.

INDUSTRIAL APPLICABILITY The present invention can be used for a control valve in which a through hole-shaped communication hole is formed in the tubular portion of a spool.

11 Ascending side spool chamber (spool chamber)
11b Second spool hole (spool hole)
12 Pump port 13 Discharge port 14 Lift control spool (spool)
14b Second land portion (cylindrical portion)
17 Communication hole 18 Outer peripheral flow path 18a Discharge side end 18t Tapered surface H Valve housing X1 First shaft core (operating shaft core)

Claims (8)

A valve housing in which a spool chamber is formed with an operating shaft core and a coaxial core, and a pump port to which hydraulic oil is supplied and a discharge port for sending out hydraulic oil are formed,
A spool housed in the spool chamber so as to be operable between a closed position and a supply position,
The spool has a tubular portion having a spool shaft center as a center, and has a plurality of communication holes having different opening areas and communicating with an internal space and an external space of the tubular portion,
When the spool is set to the closed position, it blocks the flow of hydraulic oil from the pump port to the discharge port, and when the spool is set to the supply position, the operation from the pump port A control valve in which oil flows from a part of the plurality of communication holes into the internal space of the spool and is sent out to the discharge port from a part of the other communication holes. The spool chamber includes a spool hole for accommodating the tubular portion of the spool in the middle of the pump port and the discharge port,
When the spool is in the supply position, some of the plurality of communication holes communicate with the discharge port, some of the other communication holes communicate with the pump port, and the spool has the supply position. The positional relationship between the plurality of communication holes is set so that the communication hole in the supply position is closed by the spool hole when the communication hole is operated from the above position to the closed position. Control valve. The control valve according to claim 1, wherein an opening of any one of the plurality of communication holes is exposed when viewed from any direction orthogonal to the spool axis. The control valve according to any one of claims 1 to 3, wherein the plurality of communication holes are formed in a posture orthogonal to the spool shaft core. The control valve according to any one of claims 1 to 4, wherein a plurality of the communication holes having different opening areas are arranged along the circumferential direction of the tubular portion. A plurality of the communication holes having substantially the same opening area, some of the communication holes overlap each other along the circumferential direction of the tubular portion, and the center position of the communication holes is the axis of the tubular portion. The control valve according to claim 1, wherein the control valve is arranged at a position offset in the axial direction. An outer peripheral passage having a diameter smaller than the inner diameter of the spool chamber in which the tubular portion is housed is formed on the outer periphery of the tubular portion,
The outer peripheral flow path is in a direction along the spool axis, and blocks the flow of hydraulic oil from the pump port to the discharge port when the spool is set to the closed position, and the spool is in the supply position. The control valve according to any one of claims 1 to 6, wherein the control valve is formed in a region that sends the hydraulic oil from the pump port to the discharge port when set to. The control valve according to claim 7, wherein a discharge side end portion of the outer peripheral flow path, which is arranged on the discharge port side, has a tapered surface having a smaller diameter at a position separated from the discharge port.

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