JP2020122495A - Control valve and direction switching valve - Google Patents

Abstract

To provide a control valve capable of reducing leakage of working fluid in the control valve and capable of maintaining controllability of an actuator, with a simple structure without enlarging the control valve.SOLUTION: A control valve 3a comprises a valve body 40, a spool 30 movably arranged in a spool hole 41 of the valve body 40, and an elastic member 62 that applies elastic force to the spool 30 and has different elastic constants at different positions of the spool 30.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control valve and a directional control valve.

2. Description of the Related Art Direction switching valves that control supply and discharge of working fluid to and from actuators of construction machines such as hydraulic excavators have been known. A control valve such as a directional control valve has a valve body and a spool housed in a spool hole formed in the valve body.

The valve body is provided with a supply port communicating with the main pump and a tank port communicating with the tank. Further, the actuator has a fluid chamber that accommodates a working fluid, and the valve body is provided with an actuator port that communicates with this fluid chamber. Further, the valve body is provided with a passage communicating with each port. These passages open to the spool holes and are connected through the spool holes, and together with the spool holes form a working fluid flow path. That is, the ports are connected by the flow path. A portion of the inner wall of the spool hole between the openings where the flow path opens forms an annular land portion.

The spool has a plurality of land portions that can be fitted to the annular land portion, and a cutout portion arranged between the land portions. By moving the spool in the spool hole and changing the positions of the land portion and the notch portion with respect to the annular land portion, the flow path connecting the ports can be opened and closed, and the supply and discharge of the working fluid to and from the actuator can be performed. It can be controlled.

For example, the land portion of the spool is an annular land portion between the opening portion of the actuator passage communicating with the actuator port and the opening portion of the tank passage communicating with the tank port (hereinafter, referred to as “tank-side annular land portion”). By closing the inner space of the annular land portion by fitting with, it is possible to close the flow path connecting the actuator port and the tank port. This can prevent discharge of the working fluid from the actuator. On the other hand, by separating the land portion from the tank-side annular land portion and disposing the cutout portion in the internal space of the tank-side annular land portion, the internal space can be opened. Thereby, the flow path connecting the actuator port and the tank port can be opened, and the working fluid can be discharged from the actuator.

As described above, by opening/closing the flow path connecting the actuator port and the tank port and the flow path connecting the actuator port and the supply port, it is possible to control the supply/discharge of the working fluid to/from the actuator. , The actuator can be operated as desired. When the spool is in the so-called "neutral position", the land portion of the spool closes the flow path between the actuator port and the tank port and the flow path between the actuator port and the supply port to operate the actuator. Fluid supply/discharge is stopped. As a result, the actuator does not move and its posture is maintained.

In such a control valve, for example, if the working fluid is discharged from the actuator only after the land portion is separated from the tank-side annular land portion, the actuator suddenly operates, causing shock and vibration. End up. In order to prevent such a situation, a method is known in which a notch is provided on the outer peripheral surface of the land portion of the spool to generate a so-called "front flow" of the working fluid, thereby preventing impact and vibration from being generated by the actuator. There is. For example, in order to prevent the impact and vibration from being generated by the actuator when the land part is separated from the tank-side annular land part, on the outer peripheral surface of the land part, from the end of the land part on the actuator passage side to the tank passage side, Provide a notch that extends to the middle of the land. Then, before the spool moves from the neutral position to the tank passage side and the land portion separates from the tank-side annular land portion, the actuator passage and the tank passage are communicated with each other through the notch, and the working fluid is discharged little by little from the actuator. As a result, the operation of the actuator can be started before the land part separates from the tank-side annular land part, and it is possible to prevent the occurrence of vibration and impact due to the abrupt operation of the actuator.

JP, 2005-155278, A Japanese Patent Laid-Open No. 01-269705

By the way, such a notch generally has a sufficient length so that the actuator can be stably operated before the land part separates from the annular land part.

On the other hand, if the notch has the sufficient length, unintended leakage of the working fluid may occur in the control valve. For example, when the notch as described above is provided in the land portion that fits into the tank passage-side annular land portion, the land portion has the actuator port and the tank port only at the portion on the tank passage side of the notch. The connecting flow path can be closed. The length along the moving direction of the spool of the region where this portion and the annular land portion on the tank passage side overlap is called the overlap amount. If this overlap amount is not large enough, the working fluid leaks from one side of the tank passage side annular land portion to the other side, specifically, from the actuator passage side to the tank passage side. Therefore, the working fluid in the fluid chamber of the actuator decreases, and the posture of the actuator cannot be maintained.

If the notch length is shortened and the overlap amount is increased in order to reduce the leakage of the working fluid, the controllability of the actuator is changed. For example, the time length from the start of the operation of the control valve to the start of the operation of the actuator changes. Further, the actuator cannot be sufficiently operated before the land part is separated from the annular land part. Therefore, the operator feels uncomfortable. Further, in order to prevent the leakage of the working fluid, it is conceivable to provide a check poppet at the actuator port to prevent the working fluid from flowing out from the actuator, as in the control valve described in Patent Document 2, but in this case, The control valve becomes complicated and large.

The present invention has been made in consideration of such a point, and is a control valve capable of preventing the occurrence of vibration and impact due to abrupt movement of an actuator, which is simple without increasing the size of the control valve. It is an object of the present invention to provide a control valve having a simple structure, which can reduce the leakage of the working fluid in the control valve and can maintain the controllability of the actuator. Another object of the present invention is to provide a direction switching valve including such a control valve for switching the operating direction of the hydraulic actuator.

The control valve according to the invention is
Valve body,
A spool disposed movably in the spool hole of the valve body,
An elastic member that pushes the spool with an elastic constant that changes according to the position of the spool.

Alternatively, the control valve according to the invention is
A valve body having a spool hole and an actuator passage,
A spool that moves in the spool hole and controls the actuator by supplying working fluid from a pump to the actuator connected to the actuator passage;
An elastic member that applies elastic force to the spool and has different elastic constants at different positions of the spool.

For example, the elastic constant may be the largest when the pushing distance of the elastic member by the spool is the longest.

Further, for example, when the pushing distance of the elastic member by the spool is short, the elastic constant is small, and when the pushing distance of the elastic member by the spool is long, the elastic constant may be large.

Specifically, the elastic member may include a non-linear spring.

Also, the elastic member may include a spring having two or more portions arranged in series with different spring constants.

Further, the elastic member may include two or more springs having different spring constants and arranged in series.

Alternatively, the control valve according to the invention is
A valve body having a spool hole and an actuator passage,
A spool that moves in a spool hole of the valve body and controls the actuator by supplying working fluid from a pump to the actuator connected to the actuator passage,
The elastic constant is small when the pushing distance by the spool is short, and the elastic constant is large when the pushing distance by the spool is long, and a non-linear spring that applies an elastic force to the spool.

Alternatively, the directional control valve according to the present invention includes the above control valve to switch the operating direction of the hydraulic actuator.

According to the present invention, a control valve capable of preventing vibration and impact from being generated due to abrupt movement of an actuator, has a simple structure without increasing the size of the control valve, and controls the working fluid in the control valve. It is possible to provide a control valve capable of reducing leakage and maintaining the controllability of the actuator. Further, it is possible to provide a direction switching valve that includes such a control valve and switches the operation direction of the hydraulic actuator.

FIG. 3 is a working fluid circuit diagram showing an example of a working fluid circuit using the directional control valve according to the embodiment of the present invention. Sectional drawing of the direction switching valve shown in FIG. Sectional drawing which shows typically the one side end part of the direction switching valve shown in FIG. FIG. 3 is a perspective view showing a non-linear spring which is an example of an elastic member used in the directional control valve shown in FIG. 2. The graph which shows the relationship of the load added to a spring and the pushing distance of a spring of the spring shown in FIG. Sectional drawing which shows typically the one side end part of the direction switching valve shown in FIG. Sectional drawing which shows typically the one side end part of the direction switching valve shown in FIG. Sectional drawing which shows typically the one side end part of the direction switching valve shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the drawings attached to the present specification are simplified and, for example, the drawings include portions in which the dimensions of each element, the dimensional ratio between each element, and the specific shape of each element differ from those of the actual product. Can be However, those skilled in the art can fully understand the embodiments described below and other embodiments of the present invention from such simplified drawings.

FIG. 1 shows an example of a working fluid circuit using a directional control valve according to an embodiment of the present invention.

The working fluid circuit 1 shown in FIG. 1 includes an actuator 2, a direction switching valve 3 for controlling supply and discharge of a working fluid (pressure oil in the example shown) to the actuator 2, and an actuator via the direction switching valve 3. 2 and a main pump 5 for supplying a working fluid. The working fluid circuit 1 also includes a pilot control valve (hereinafter, referred to as a “remote control valve”) 4 for controlling the operation of the directional control valve 3, a pilot pump 6, and a tank 7.

In the illustrated example, the actuator 2 is a hydraulic actuator. More specifically, the hydraulic actuator 2 is a hydraulic cylinder having a piston rod 2r, and has a head side fluid chamber 2a and a rod side fluid chamber 2b.

The direction switching valve 3 switches the operation direction of the hydraulic actuator 2, and includes the control valve 3a. The direction switching valve 3 may include other functional units other than the control valve 3a.

The control valve 3a and the direction switching valve 3 are connected to the main pump 5 and the tank 7. The control valve 3a has a spool 30, and by moving the spool 30 in the first direction (the left-right direction in FIG. 1) D1, the main pump 5 and the tank 7, the head-side fluid chamber 2a of the actuator 2, The connection state with the rod-side fluid chamber 2b can be changed.

As shown in FIG. 1, the control valve 3a includes pilot pressure acting portions 51 and 52 at both ends in the first direction D1. The pilot pressure acting portions 51 and 52 are means for applying pilot pressure to the end portion of the spool 30 for the purpose of driving the spool 30. By loading pilot pressure on the pilot pressure acting portion 51 located on the other side of the first direction D1 (on the left side in FIG. 1), the spool 30 is moved from the neutral position shown in FIG. It can be moved to the first operating position which has been moved to the right in FIG. 1). Further, by loading pilot pressure on the pilot pressure acting portion 52 located on one side of the first direction D1 (on the right side of FIG. 1), the spool 30 is moved from the neutral position shown in FIG. It can be moved to the second operating position, which has moved to the side (to the left in FIG. 1).

The control valve 3a also includes elastic members 61 and 62 that apply an elastic force to the spool 30 in the first direction D1. When the pilot pressure is not generated in the pilot pressure acting portions 51 and 52 by the elastic members 61 and 62, the spool 30 is held at the neutral position shown in FIG.

When the spool 30 is in the neutral position, the main pump 5 and the tank 7 are not connected to either the head-side fluid chamber 2a or the rod-side fluid chamber 2b of the actuator 2 (see FIG. 1), and the actuator 2 There is no supply or discharge of working fluid to or from. On the other hand, when the spool 30 is in the first operating position, the main pump 5 and the tank 7 are connected to the rod-side fluid chamber 2b and the head-side fluid chamber 2a of the actuator 2, respectively. As a result, the working fluid is supplied to the rod-side fluid chamber 2b, at the same time the working fluid is discharged from the head-side fluid chamber 2a, and the piston rod 2r moves in the pulling direction. When the spool 30 is in the second operating position, the main pump 5 and the tank 7 are connected to the head side fluid chamber 2a and the rod side fluid chamber 2b of the actuator 2, respectively. As a result, the working fluid is supplied to the head-side fluid chamber 2a, at the same time the working fluid is discharged from the rod-side fluid chamber 2b, and the piston rod 2r moves in the exit direction. In this way, by moving the spool 30 of the control valve 3a and changing the connection state between the main pump 5 and the tank 7 and the head side fluid chamber 2a and the rod side fluid chamber 2b of the actuator 2, the actuator 2 is desired. Can be operated like.

The remote control valve 4 is a valve for controlling the pilot pressure described above. Here, pilot lines 11 and 12 are connected to the pilot pressure acting portions 51 and 52 of the control valve 3a, respectively. The remote control valve 4 connects the pilot lines 11 and 12 on the side corresponding to the operating direction of the operating lever 4a and the pilot pump 6 to supply working fluid to the pilot lines 11 and 12. As a result, pilot pressure is generated in the pilot pressure acting portions 51 and 52 connected to the pilot lines 11 and 12. It should be noted that the remote control valve 4 makes the other pilot lines 12, 11 communicate with the tank 7 when the one pilot lines 11, 12 communicate with the pilot pump 6. Further, when the operation lever 4a is not operated, the remote control valve 4 connects both pilot lines 11 and 12 to the tank 7.

Next, the control valve 3a will be described in more detail with reference to FIGS. 2 and 3. FIG. 2 shows a cross section along the longitudinal direction of the spool 30 of the control valve 3a shown in FIG. FIG. 3 is a partially enlarged view schematically showing one end portion of the control valve 3a shown in FIG.

The control valve 3a shown in FIG. 2 has, as main components, an elongated spool 30 extending along the first direction D1, a valve body 40 provided with a spool hole 41 for accommodating the spool 30, and a valve body 40. And valve covers 53 and 54 attached to both sides.

The valve covers 53 and 54 are tubular members each having a connecting portion whose one end in the first direction D1 is connected to the pilot lines 11 and 12. The valve covers 53 and 54 house the other end and one end of the spool 30, respectively. The insides of the valve covers 53 and 54 are connected to the pilot lines 11 and 12, respectively. When the working fluid is supplied to the pilot lines 11 and 12, pilot pressure is generated inside the valve covers 53 and 54, and the pilot pressures are increased. It acts on the other end surface 31 and the one end surface 32 of the spool 30. That is, the insides of the valve covers 53 and 54 form the pilot pressure acting portions 51 and 52 described above. The other end surface 31 and the one end surface 32 of the spool 30 are pressure receiving surfaces on which the pilot pressure generated inside the valve covers 53 and 54 acts.

Inside the valve covers 53 and 54, elastic members 61 and 62 that apply elastic force to the spool 30 toward one side and the other side of the first direction D1 are arranged, respectively. In the illustrated example, the elastic members 61 and 62 are springs.

A spool hole 41 extending in the first direction D1 is formed in the valve body 40. The spool 30 is movably arranged in the spool hole 41. Further, the valve body 40 is formed with various passages including a supply passage 44, an actuator passage 45, and a tank passage 46. Although not shown, the valve body 40 is connected to a supply port connected to the main pump 5, a head side actuator port connected to the head side fluid chamber 2a of the actuator 2, and a rod side fluid chamber 2b of the actuator 2. A rod side actuator port and a tank port connected to the tank 7.

The supply passage 44 communicates with the supply port. In the example shown in FIG. 2, the supply passage 44 is branched midway, one forming a first supply passage 44a and the other forming a second supply passage 44b. The first and second supply passages 44 a and 44 b open in the spool hole 41.

The actuator passage 45 has a first actuator passage 45a and a second actuator passage 45b. The first and second actuator passages 45a and 45b communicate with the head side actuator port and the rod side actuator port, respectively. Therefore, the first actuator passage 45a is connected to the head side fluid chamber 2a of the actuator 2 via the head side actuator port. Further, the second actuator passage 45b is connected to the rod side fluid chamber 2b of the actuator 2 via the rod side actuator port. The first and second actuator passages 45 a and 45 b are also open to the spool hole 41.

The tank passage 46 communicates with the tank port. In the example shown in FIG. 2, the tank passage 46 branches in the middle so that one side forms the first tank passage 46a and the other side forms the second tank passage 46b. The first and second tank passages 46 a and 46 b are opened to the spool hole 41, respectively.

On the inner wall 41a of the spool hole 41, the opening of the first tank passage 46a, the opening of the first actuator passage 45a, the opening of the first supply passage 44a, and the second supply passage 44b are arranged in this order from the valve cover 54 side. The opening, the opening of the second actuator passage 45b, and the opening of the second tank passage 46b are formed. An area between the openings of the inner wall 41a of the spool hole 41 forms an annular land portion RL.

Note that, hereinafter, the annular land portion RL between the opening portion of the first tank passage 46a and the opening portion of the first actuator passage 45a is referred to as "first tank passage-side annular land portion RL1". Further, the annular land portion RL between the opening of the first actuator passage 45a and the opening of the first supply passage 44a is referred to as a "first supply passage-side annular land portion RL2". The annular land portion RL between the opening of the second supply passage 44b and the opening of the second actuator passage 45b is referred to as a "second supply passage-side annular land portion RL3". Further, the annular land portion RL between the opening of the second actuator passage 45b and the opening of the second tank passage 46b is referred to as a "second tank passage-side annular land portion RL4".

The spool 30 is a columnar member as a whole, and has a plurality of land portions L arranged apart from each other in the first direction D1 and a plurality of cutout portions M provided between the land portions L. The outer diameter of each land portion L is substantially equal to the inner diameter of the annular land portion RL of the spool hole 41. The outer diameter of each notch M is smaller than the inner diameter of the annular land RL.

When each land part L is fitted in the corresponding annular land part RL, the internal space of the annular land part RL is closed. As a result, the flow path between the two ports connected to the two passages that open on both sides of the land portion L is blocked. On the other hand, when the land portion L is separated from the corresponding annular land portion RL and the cutout portion M is disposed in the internal space of the annular land portion RL, the operation between the two passages opened on both sides of the annular land portion RL. Fluid flow is allowed. That is, the flow path between the two ports connected to the two passages is opened. In this way, the spool 30 can change the flow direction of the working fluid by connecting the two ports with the notch M or blocking the two ports with the land L.

Note that, hereinafter, the land portion L corresponding to the first tank passage-side annular land portion RL1 is referred to as “first tank passage-side land portion L1”. The land portion L corresponding to the first supply passage side annular land portion RL2 is referred to as a "first supply passage side land portion L2". The land portion L corresponding to the second supply passage side annular land portion RL3 is referred to as a "second supply passage side land portion L3". The land portion L corresponding to the second tank passage side annular land portion RL4 is referred to as a "second tank passage side land portion L4". The cutout portion M between the first tank passage side land portion L1 and the first supply passage side land portion L2 is referred to as a "first cutout portion M1". In addition, the cutout portion M between the second supply passage side land portion L3 and the second tank passage side land portion L4 is referred to as a "second cutout portion M2".

Specifically, when the spool 30 is arranged at the neutral position shown in FIG. 2, the first tank passage side land portion L1 fits into the first tank passage side annular land portion RL1 and the first actuator passage 45a. And the first tank passage 46a are disconnected from each other. As a result, the flow path that connects the head-side actuator port and the tank port is closed. Further, the first supply passage side land portion L2 is fitted into the first supply passage side annular land portion RL2 to cut off the connection between the first actuator passage 45a and the first supply passage 44a. As a result, the flow path that connects the head-side actuator port and the supply port is closed. In addition, the second tank passage side land portion L4 is fitted to the second tank passage side annular land portion RL4 to shut off between the second actuator passage 45b and the second tank passage 46b. As a result, the flow path connecting the rod-side actuator port and the tank port is closed. In addition, the second supply passage side land portion L3 is fitted to the second supply passage side annular land portion RL3 to shut off between the second actuator passage 45b and the second supply passage 44b. As a result, the flow path that connects the rod-side actuator port and the supply port is closed. As described above, the working fluid from the main pump 5 connected to the supply port is not supplied to any of the fluid chambers 2a and 2b of the actuator 2. Further, the working fluid in any of the fluid chambers 2a and 2b of the actuator 2 is not discharged to the tank 7 connected to the tank port. Therefore, the actuator 2 does not operate and its posture is maintained.

When the spool 30 is moved in the spool hole 41 from the neutral position shown in FIG. 2 to one side in the first direction (right side in FIG. 2) to the first operating position, the first tank passage-side land portion L1 is located in the first tank passage. A first cutout portion M1 is disposed in the internal space of the first tank passage-side annular land portion RL1 which is separated from the side annular land portion RL1. As a result, the first actuator passage 45a and the first tank passage 46a communicate with each other through the space between the first cutout portion M1 and the first tank passage-side annular land portion RL1. Therefore, the flow path connecting the head side actuator port and the tank port is opened. At this time, the first supply passage side land portion L2 is still fitted to the first supply passage side annular land portion RL2, and the first supply passage 44a and the first actuator passage 45a are not blocked. Up to. Therefore, the flow path connecting the head-side actuator port and the supply port remains closed. Further, the second supply passage side land portion L3 is separated from the second supply passage side annular land portion RL3, and the second cutout portion M2 is arranged in the internal space of the second supply passage side annular land portion RL3. As a result, the second actuator passage 45b and the second supply passage 44b communicate with each other through the space between the second cutout portion M2 and the second supply passage-side annular land portion RL3. Therefore, the flow path connecting the rod-side actuator port and the supply port is opened. At this time, the second tank passage-side land portion L4 remains fitted in the second tank passage-side annular land portion RL4, and the second actuator passage 45b and the second tank passage 46b remain blocked. is there. Therefore, the flow path connecting the rod-side actuator port and the tank port remains closed. As described above, the working fluid from the main pump 5 connected to the supply port enters the rod-side fluid chamber 2b through the second supply passage 44b, the internal space of the second supply passage-side annular land portion RL3, and the second actuator passage 45b. Inflow. Further, the working fluid in the head side fluid chamber 2a flows into the tank 7 through the first actuator passage 45a, the internal space of the first tank passage side annular land portion RL1 and the first tank passage 46a. As a result, the piston rod 2r of the actuator 2 moves in the pulling direction.

When the spool 30 is moved in the spool hole 41 from the neutral position shown in FIG. 2 to the other side in the first direction D1 (left side in FIG. 2) to the second operating position, the first supply passage side land portion L2 is used for the first supply. A first cutout portion M1 is arranged in the internal space of the first supply passage-side annular land portion RL2, which is separated from the passage-side annular land portion RL2. As a result, the first actuator passage 45a and the first supply passage 44a communicate with each other through the space between the first cutout portion M1 and the first supply passage-side annular land portion RL2. Therefore, the flow path connecting the head side actuator port and the supply port is opened. At this time, the first tank passage-side land portion L1 remains fitted in the first tank passage-side annular land portion RL1, and the first actuator passage 45a and the first tank passage 46a remain blocked. is there. Therefore, the flow path connecting the head-side actuator port and the tank port remains closed. Further, the second tank passage side land portion L4 is separated from the second tank passage side annular land portion RL4, and the second cutout portion M2 is arranged in the internal space of the second tank passage side annular land portion RL4. As a result, the second actuator passage 45b and the second tank passage 46b communicate with each other through the space between the second cutout portion M2 and the second tank passage-side annular land portion RL4. Therefore, the flow path connecting the rod-side actuator port and the tank port is opened. At this time, the second supply passage side land portion L3 remains fitted in the second supply passage side annular land portion RL3, and the second actuator passage 45b and the second supply passage 44b remain blocked. is there. Therefore, the flow path connecting the rod-side actuator port and the supply port remains closed. As described above, the working fluid from the main pump 5 connected to the supply port passes through the first supply passage 44a, the internal space of the first supply passage-side annular land portion RL2, and the first actuator passage 45a, and the head-side fluid chamber. It flows into 2a. The working fluid in the rod-side fluid chamber 2b flows into the tank 7 through the second actuator passage 45b, the internal space of the second tank passage-side annular land portion RL4, and the second tank passage 46b. As a result, the piston rod 2r of the actuator 2 moves in the exit direction.

In this way, the spool 30 moves in the spool hole 41 and enables the supply of the working fluid from the pump 5 to the actuator 2 connected to the actuator passage 45. Further, the control valve 3a can switch the operation direction of the actuator 2 by switching the moving direction of the spool 30.

In such a control valve 3a, for example, when the working fluid is discharged from the head side fluid chamber 2a of the actuator 2 to retract the rod 2r, the first tank passage side annular land portion RL1 to the first tank passage side land portion L1 are If the flow path connecting the head-side actuator port and the tank port is opened only after the actuator is detached, the actuator 2 may suddenly operate, causing shock and vibration. In order to prevent such a situation, it is known to provide a notch extending in the moving direction of the spool on the outer peripheral surface of the land portion. That is, when the spool is moved, before the land portion is separated from the annular land portion, the passages that open on both sides of the annular land portion are communicated with each other through the notches so that the so-called working fluid flows from one passage to the other passage. Cause a pre-flow of. With this, the actuator can start the operation before the land part separates from the annular land part, and it is possible to prevent the occurrence of vibration and impact due to the abrupt operation of the actuator.

In the example shown in FIGS. 2 and 3, the first notch N1 is provided on the outer peripheral surface of the first tank passage side land portion L1. As well shown in FIG. 3, the first notch N1 is elongated in the moving direction D1 of the spool 30, and extends from the end of the first tank passage side land portion L1 on the first actuator passage 45a side to the first tank passage 46a. Extending to the side of. Since the first notch N1 is provided on the outer peripheral surface of the first tank passage side land portion L1, the spool 30 moves to one side in the first direction D1 (right side in FIG. 3) and the first tank passage side land is formed. Before the portion L1 separates from the first tank passage-side annular land portion RL1, the first actuator passage 45a and the first tank passage 46a are communicated with each other through the first notch N1, and the first actuator passage 45a is connected to the first tank passage 45a. A pre-flow of working fluid through the first notch N1 can be generated at 46a. That is, the working fluid can be discharged little by little from the first actuator passage 45a to the first tank passage 46a through the first notch N1. In the following description, in the first tank passage side land portion L1, the first tank passage side from the position where the internal space of the first tank passage side annular land portion RL1 is closed to the position where the first tank passage side annular land portion RL1 is opened is opened. A portion on the front side (right side in FIG. 3) in the moving direction (right direction in FIG. 3) of the land portion L1 (spool 30) is referred to as a first notch non-forming portion L1a.

Here, as shown in FIG. 3, when the spool 30 is in the neutral position, the internal space of the first tank passage side annular land portion RL1 is defined by the first notch non-formation portion L1a of the first tank passage side land portion L1. It is closed. Therefore, when the spool 30 is in the neutral position, the pre-flow of the working fluid through the first notch N1 does not occur. The pre-flow of the working fluid through the first notch N1 moves the spool 30 to one side of the first direction D1 (right side in FIG. 3), and one side end of the first notch N1 forms the first tank passage 46a. When you meet, it starts. This causes the actuator 2 to start operating. The forward flow of the working fluid through the first notch N1 continues until the first tank passage side land portion L1 separates from the first tank passage side annular land portion RL1.

By the way, generally, such a notch has a sufficient length so that the actuator can be sufficiently operated before the land portion is separated from the annular land portion. Therefore, the following problems have occurred. First, the longer the notch N1 is, the more the notch forming portion L1a of the land portion L1 and the annular land portion RL1 overlap each other along the moving direction D1 of the spool 30 when the spool 30 is in the neutral position. The length (hereinafter, referred to as “overlap amount W1”) is shortened. When the overlap amount W1 is short, even if the spool 30 is arranged in the neutral position to maintain the posture of the actuator 2, one side (the passage 45a side) of the annular land portion RL1 to the other side (the passage 46a side). ), the working fluid leaks out, and the posture of the actuator 2 cannot be maintained.

In consideration of such a point, in the illustrated example, the length of the first notch N1 is made shorter than in the conventional case, and the overlap amount W1 when the spool 30 is at the neutral position is set larger than that in the conventional case. There is.

By the way, in general, when the overlap amount or the notch length is changed, the controllability of the actuator is also changed. For example, even if the operation lever of the remote control valve is operated as in the conventional case, the time length from the start of the operation of the operation lever to the start of the forward flow of the working fluid is different from the conventional time. The time length from the start of the operation to the operation of the actuator is also different from the conventional one. Further, when the length of the notch is shortened, the length of time during which the forward flow of the working fluid is continued becomes shorter than in the conventional case, so that the actuator cannot be sufficiently operated before the land portion is separated from the annular land portion. This makes the operator of the operating lever feel uncomfortable.

In consideration of such circumstances, the control valve 3a of the present embodiment has a sufficiently large overlap amount W1 between the first tank passage side land portion L1 and the first tank passage side annular land portion RL1 at the neutral position. The device is designed to maintain the controllability of the actuator 2 while setting.

Specifically, as the elastic member 62, elastic members having different elastic constants at different positions of the spool 30 are used. In other words, an elastic member that pushes the spool 30 with an elastic constant that changes according to the position of the spool 30 is used. Here, the elastic constant is a load applied to the elastic member 62, and a pushing distance of the elastic member 62 by the spool 30 (a moving distance from the neutral position of the spool 30 to the elastic member 62 in the illustrated example) is x. Is a constant that satisfies the relation of k=F/x.

In the illustrated example, the elastic constant k of the elastic member 62 is the smallest when the pushing distance x of the elastic member 62 by the spool 30 is the shortest. In other words, the elastic constant k of the elastic member 62 becomes the largest when the pushing distance x of the elastic member 62 by the spool 30 is the longest.

More specifically, the elastic member 62 includes a non-linear spring as shown in FIG. Here, the “non-linear spring” means a spring in which the relationship between the load F applied to the spring and the pushing distance (spring contraction amount) x of the spring is not expressed by a linear expression. More specifically, the load F applied to the spring and the pushing distance x of the spring have a relationship as shown in, for example, FIG. 5, and the elastic constant k changes according to the pushing distance x of the spring. That is. As described above, since the elastic member 62 is a spring in the illustrated example, the elastic constant is also referred to as “spring constant” below.

In the illustrated example, the elastic member 62 includes a first spring element 62a and a second spring element 62b having different spring constants. The first spring element 62a and the second spring element 62b are arranged in the first direction D1 to form a series of springs. The spring constant k of the elastic member 62 is the spring constant ka when the pushing distance x of the elastic member 62 is 0 to x1, and is between x1 and x2 where the pushing distance x of the spring is greater than 0 to x1. , A spring constant kb larger than the spring constant ka. The elastic member 62 is easily deformed when the spring pushing distance x is 0 to x1, and is hard to be deformed when x1 to x2. Accordingly, the spool 30 can be moved relatively quickly when the pushing distance x of the elastic member 62 by the spool 30 is in the range of 0 to x1, and the spool 30 is moved relatively slowly when the pushing distance x is in the range of x1 to x2. be able to.

In the example shown in FIG. 4, the elastic member 62 is formed as a continuous spring, but it is not limited to this. For example, the elastic member 62 may include two or more parts arranged in series with different spring constants. Further, the elastic member 62 may include two or more separate springs having different spring constants and arranged in series.

In the example shown in FIG. 5, the elastic constant k of the elastic member 62 changes stepwise, but the elastic constant k may change continuously. In this case, the elastic constant k of the elastic member 62 decreases when the pushing distance x of the elastic member 62 by the spool 30 is short. In other words, the elastic constant k of the elastic member 62 increases as the pushing distance of the elastic member 62 by the spool 30 increases.

By using the elastic member 62 whose elastic constant changes according to the position of the spool 30, the length of the first notch N1 is made shorter than before, and the first tank passage side land portion L1 at the neutral position is formed. Even if the overlap amount W1 with the first tank passage side annular land portion RL1 is made longer than in the conventional case, the controllability of the actuator 2 can be suppressed from changing. Specifically, even if the length of the first notch N1 is made shorter than in the conventional case and the overlap amount W1 is made larger than in the conventional case, the relationship between the pushing distance x and the spring constant k is appropriately determined. The spool 30 can be moved faster than before until the one end of the first notch N1 faces the first tank passage 46a from the neutral position. After the front flow of the working fluid has started facing the first tank passage 46a, the spool 30 can be moved more slowly than before. As a result, the time length from the start of the operation of the lever 4a to the start of the pre-flow of the working fluid (therefore, the time length from the start of the operation of the actuator 2), and from the start of the pre-flow of the working fluid It is possible to maintain the time length until the first tank passage side land portion L1 separates from the first tank passage side annular land portion RL1 (therefore, the time duration during which the forward flow of the working fluid continues) to the same time length as the conventional one. it can. Thereby, the controllability of the actuator 2 when moving the spool 30 from the neutral position to the first operating position can be maintained as in the conventional case.

In the example shown in FIG. 2, a second notch N2 similar to the first notch N1 is provided on the outer peripheral surface of the second tank passage side land portion L4. The second notch N2 is elongated along the moving direction D1 of the spool 30 and extends from the end of the second tank passage side land portion L4 on the second actuator passage 45b side toward the second tank passage 46b. In this case, when the spool 30 is moved from the neutral position to the other side in the first direction D1 (left side in FIG. 2) to the second operating position, the second tank passage side land portion L4 becomes the second tank passage side annular land portion. Prior to leaving RL4, a pre-flow of working fluid can be generated from second actuator passage 45b to second tank passage 46b through second notch N2.

The length of the second notch N2 is shorter than that of the conventional one, like the first notch N1. Accordingly, the overlap amount W2 between the second tank passage side land portion L4 and the second tank passage side annular land portion RL4 when the spool 30 is in the neutral position (the land portion when the spool 30 is in the neutral position) A length of the overlapping region of the second notch-unformed portion L4a of L4 and the annular land portion RL4 along the moving direction D1 of the spool 30. Here, the "second notch-unformed portion L4a" means the second tank. Of the passage side land portion L4, the second tank passage side land portion L4 (of the spool 30 of the spool 30 from the position where the inner space of the second tank passage side annular land portion RL4 is closed to the position where the second notch N2 is closed is opened). The front side (left side in FIG. 2) in the moving direction D1 can be made larger than before, and one side of the second tank passage side annular land portion RL4 (second actuator passage 45b). It is possible to reduce the leakage of the working fluid from the side) to the other side (the side of the second tank passage 46b). The elastic member 61 has the same elastic constant as the elastic member 62. More specifically, the elastic member 61 is a non-linear spring similar to the elastic member 62. For this reason, even if the length of the second notch N2 is made shorter than in the conventional case and the overlap amount W2 is secured larger than in the conventional case, the actuator 2 when moving the spool 30 from the neutral position to the second operating position. The controllability can be maintained as before.

Next, the operation of the control valve 3a will be described with reference to FIGS. Hereinafter, the operation of the control valve 3a when the spool is moved from the neutral position shown in FIGS. 2 and 3 to the first operating position will be described.

First, when the operation lever 4a of the remote control valve 4 is not operated, the pilot lines 11 and 12 are both in communication with the tank 7. Therefore, the working fluid is not supplied from the pilot pump 6 to the pilot lines 11 and 12, and no pilot pressure is generated in any of the pilot pressure acting portions 51 and 52. Therefore, the pilot pressure does not act on the spool 30, and the spool 30 is held at the neutral position shown in FIGS. 1 and 2 by the elastic force of the elastic members 61 and 62. At this time, as well shown in FIG. 3, the first tank passage-side land portion L1 is fitted into the first tank passage-side annular land portion RL1 and the second tank passage-side land portion L4 is connected to the second tank passage. It is fitted to the side annular land portion RL4. Since the overlap amount W1 between the first tank passage side land portion L1 and the first tank passage side annular land portion RL1 is set to be sufficiently large, the working fluid is supplied from the first actuator passage 45a side to the first tank. Leakage to the passage 46a side is reduced. This reduces the outflow of the working fluid from the head-side fluid chamber 2a of the actuator 2. Further, as shown in FIG. 2, since the overlap amount W2 between the second tank passage side land portion L4 and the second tank passage side annular land portion RL4 is set to be sufficiently large, the working fluid is the second actuator. Leakage from the passage 45b side to the second tank passage 46b side is reduced. This reduces the outflow of the working fluid from the rod-side fluid chamber 2b of the actuator 2. As a result, the posture of the actuator 2 is maintained.

Next, when moving the spool 30 from the neutral position to the first operating position, the operation lever 4a of the remote control valve 4 is operated to make the pilot pump 6 and the pilot line 11 communicate with each other, and the pilot pump 6 to the pilot line 11 is connected. Supply working fluid. The working fluid supplied to the pilot line 11 flows into the valve cover 53. As a result, a pilot pressure corresponding to the operation amount of the operation lever 4a is generated in the valve cover 53.

When the pilot pressure is generated in the valve cover 53, the spool 30 moves toward one side of the first direction D1 (the right side in FIG. 3) by a distance corresponding to the pilot pressure and pushes the elastic member 62. At this time, until the spool 30 moves from the neutral position shown in FIG. 3 to the position shown in FIG. 6 by the distance x1, that is, one side end of the first notch N1 is at the first tank passage side annular land RL1. The first actuator passage 45a and the first tank passage 46a do not communicate with each other through the first notch N1 until the end portion of the first tank passage 46a side is reached, and the pre-flow of the working fluid through the first notch N1 does not occur. Does not happen. Thereafter, as shown in FIG. 7, when the spool 30 further moves to one side in the first direction D1 and one end of the first notch N1 faces the first tank passage 46a, the first actuator passage 45a is formed. The first tank passage 46a communicates with the first notch N1, and a pre-flow of the working fluid through the first notch N1 occurs from the first actuator passage 45a to the first tank passage 46a. As a result, the working fluid in the rod-side fluid chamber 2b of the actuator 2 flows out, and the actuator 2 starts operating. Specifically, the rod 2r starts to move in the pulling direction. Then, the spool 30 further moves to one side in the first direction D1 (right side in FIG. 8) to the position shown in FIG. 8, and the first tank passage side land portion L1 separates from the first tank passage side annular land portion RL1. Then, the first actuator passage 45a and the first tank passage 46a communicate with each other through the space between the first tank passage-side annular land portion RL1 and the first cutout portion M1. As a result, the flow rate of the working fluid flowing from the first actuator passage 45a to the first tank passage 46a is increased, and the operating speed of the actuator 2 is increased. Specifically, the pulling speed of the rod 2r becomes faster.

In the illustrated example, the spool 30 is compared according to the elastic constant ka until the spool 30 moves from the neutral position shown in FIG. 3 to the position shown in FIG. At a relatively high speed, and thereafter (and thus after the pre-flow of the working fluid has started), at a relatively low speed according to the elastic constant kb.

By adjusting the elastic constants ka and kb of the elastic member 62 and the pushing distance x1 of the elastic member 62 when the elastic constant of the elastic member 62 is the elastic constant ka, the first notch after the spool 30 starts to move. A desired time length can be set as a time length until one side end portion of N1 faces the first tank passage 46a and a time length during which the forward flow of the working fluid through the first notch N1 is continued. That is, the controllability of the actuator 2 can be made as desired, for example, similar to the conventional one. The elastic constants ka and kb of the elastic member 62 and the pushing distance x1 can be adjusted, for example, by adjusting the lengths and spring constants of the spring elements 62a and 62b forming the elastic member 62.

In addition, in the present embodiment described above, the case where the length of the first notch N1 is set shorter than in the conventional case and the overlap amount W1 is set larger than that in the conventional case has been described. In this case, by simply replacing the spool and elastic member of the conventional control valve with the above-described spool 30 and elastic member 62, that is, without making any change to the valve body, the control of the present embodiment can be performed easily and inexpensively. The valve 3a and the directional control valve 3 can be realized. Further, the control valve 3a or the direction switching valve 3 does not become large.

Of course, the method for sufficiently securing the overlap amount W1 is not limited to the example described above. For example, the length of the first notch N1 remains the same as the conventional one, and the length of the first tank passage side annular land portion RL1 and/or the first tank passage side land portion L1 is made longer than in the conventional case, so that the overlap amount is increased. W1 may be sufficiently secured. Also in this case, the controllability of the actuator 2 can be maintained by using the same elastic member as the elastic member 62 described above.

The control valve 3a according to the present embodiment described above has the valve body 40, the spool 30 movably arranged in the spool hole 41 of the valve body 40, and the elastic constant k that changes according to the position of the spool 30. And an elastic member 62 that pushes the spool 30 with.

With such a control valve 3a, the moving speed of the spool can be relatively fast or slow according to the position of the spool 30. Therefore, for example, in order to reduce the leakage of the working fluid inside the control valve 3a, the length of the notch N1 provided in the land portion L1 of the spool 30 is shortened and the annular land to which the land portion L1 is fitted. Even if the overlap amount W1 with the portion RL1 is set large, the controllability of the actuator 2 via the control valve 3a can be maintained.

More specifically, the control valve 3a according to the present embodiment moves to the valve main body 40 having the spool hole 41 and the actuator passage 45, and the inside of the spool hole 41 to move the pump 5 to the actuator 2 connected to the actuator passage 45. A spool 30 that controls the actuator 2 by making it possible to supply the working fluid from the above, and an elastic member 62 that applies an elastic force to the spool 30 and has different elastic constants k at different positions of the spool 30.

Further, in the present embodiment, the elastic constant k becomes the largest when the pushing distance of the elastic member 62 by the spool 30 is the longest. In this case, when the elastic member 62 extends the longest, the spool 30 can be moved fastest. Therefore, for example, even if the overlap amount W1 with the annular land portion RL1 with which the land portion L1 provided with the notch N1 is fitted is set to be larger than the conventional value, the spool 30 starts moving and then passes through the notch N1. The time length until the pre-flow of the working fluid starts can be made similar to the conventional one.

As described above, when the pushing distance of the elastic member 61 by the spool 30 is short, the elastic constant k may be small, and when the pushing distance of the elastic member 62 by the spool 30 is long, the elastic constant k may be large. Also in this case, if the elastic member 62 is long, the spool 30 can be moved at a high speed. Therefore, for example, even if the overlap amount W1 with the annular land portion RL1 with which the land portion L1 provided with the notch N1 is fitted is set to be larger than the conventional value, the spool 30 starts moving and then passes through the notch N1. The time length until the pre-flow of the working fluid starts can be made similar to the conventional one.

Further, in the present embodiment, the elastic member 62 includes a non-linear spring. In this case, the elastic member 61 described above can be easily manufactured at low cost.

Alternatively, the elastic member 62 may include a spring having two or more portions arranged in series with different spring constants. Also in this case, the elastic member 62 described above can be easily manufactured at low cost.

Alternatively, the elastic member 62 may include two or more springs arranged in series with different spring constants. Also in this case, the elastic member 62 described above can be easily manufactured at low cost.

Further, the control valve 3 a according to the present embodiment moves in the valve body 40 having the spool hole 41 and the actuator passage 45, and in the spool hole 41 of the valve body 40, and the pump 5 is connected to the actuator 2 connected to the actuator passage 45. And a spool 30 that controls the actuator 2 by making it possible to supply the working fluid from. Further, the control valve 3a includes a non-linear spring that gives a small elastic constant k when the pushing distance by the spool 30 is short, and a large elastic constant k when the pushing distance by the spool 30 is long, and which gives an elastic force to the spool 30.

With such a control valve 3a, the moving speed of the spool 30 can be relatively fast or slow depending on the position of the spool 30. Therefore, for example, in order to reduce the leakage of the working fluid inside the control valve 3a, the length of the notch N1 provided in the land portion L1 of the spool 30 is shortened and the annular land to which the land portion L1 is fitted. Even if the overlap amount W1 with the portion RL1 is set large, the controllability of the actuator 2 via the control valve 3a can be maintained.

Further, the direction switching valve 3 according to the present embodiment switches the operation direction of the hydraulic actuator 2 including the control valve 3a described above.

The present invention is not limited to the above embodiments. For example, various modifications may be added to each element of the above-described embodiment. Further, forms including components and/or methods other than the components and/or methods described above are also included in the embodiments of the present invention. Further, a mode in which some of the components and/or methods described above are not included is also included in the embodiments of the present invention. Further, the effects produced by the present invention are not limited to the above-mentioned effects, and peculiar effects according to the specific configurations of the respective embodiments can be exhibited.

1 Working Fluid Circuit 2 Actuator 2a Head Side Fluid Chamber 2b Rod Side Fluid Chamber 3 Directional Switching Valve 3a Control Valve 4 Remote Control Valve 30 Spool 40 Valve Body 44 Supply Passage 44a First Supply Passage 45 Actuator Passage 45a First Actuator Passage 46 Tank Passage 46a First tank passage 61, 62 Elastic member L Land portion L1 First tank passage side land portion L2 First supply passage side land portion M Notch portion M First notch portion N1 First notch RL Annular land portion RL1 First tank passage Side annular land portion RL2 First supply passage side annular land portion

Claims (7)

A valve body having a spool hole and an actuator passage,
A spool that moves in the spool hole and controls the actuator by supplying working fluid from a pump to the actuator connected to the actuator passage;
An elastic member that applies an elastic force to the spool and that has different elastic constants at different positions of the spool. The control valve according to claim 1, wherein when the pushing distance of the elastic member by the spool is short, the elastic constant is small, and when the pushing distance of the elastic member by the spool is long, the elastic constant is large. The control valve according to claim 1, wherein the elastic constant becomes the largest when the pushing distance of the elastic member by the spool is the longest. The control valve according to claim 1, wherein the elastic member includes a non-linear spring. The control valve according to any one of claims 1 to 3, wherein the elastic member includes a spring having two or more portions arranged in series with different spring constants. A valve body having a spool hole and an actuator passage,
A spool that moves in a spool hole of the valve body and controls the actuator by supplying working fluid from a pump to the actuator connected to the actuator passage,
A control valve comprising: a non-linear spring that gives a small elastic constant when the pushing distance by the spool is short, and a large elastic constant when the pushing distance by the spool is long, and which gives an elastic force to the spool. A direction switching valve including the control valve according to any one of claims 1 to 6 for switching the operation direction of a hydraulic actuator.

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