JPS5930922B2 - Compact fluid motor control system with float position - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fluid-powered motors, and more particularly to a control system that allows an operator to select any one of several different operating modes of the motor.

Typically, fluid-driven motors are connected by a spool or other valve between a hold position when the motor is stopped, another position that operates the motor in a first direction, and yet another position that operates the motor in the opposite direction. Controlled by a directional control valve such that the member is movable.

In many cases, the motor carries a load that tends to move sometimes faster than given by the velocity of the fluid supplied to the motor through the directional control valve.

For example, a power loader of the type used for handling loose soil or other bulk materials, described in U.S. Pat. The vehicle typically has a packet with a raised and lowered movement provided by a fluid motor controlled by the vehicle operator.

When the load packet is lowered, the weight tends to drive the fluid motor faster than the drive fluid supply rate.

Under this condition motor cavitation, which is well known to produce undesirable effects unless compensation measures are provided, will occur.

One means of preventing cavitation is a replenishment valve that senses incipient cavitation and opens to replenish the drive fluid flow to the motor with fluid released from the motor.

The operation of these conventional replenishment valves is automatic and is not subject to operator control.

In some cases it is desirable to intentionally cause the motor to respond to the load force rather than the velocity of the drive fluid delivered by the pump.

For example, in the above-mentioned loader, considerable time and power savings are realized by allowing the loaded packet to fall under the influence of weight faster than can be provided by the speedboat of the drive fluid that can be supplied to the motor. Ru.

This is provided by the fourth position of the directional control valve, commonly known as the float position.

This float mode of operation is achieved by manually communicating the two inlet and outlet ports of the motor with each other and with the return path ζ to the tank.

Providing a float position to a control system may be useful for purposes other than using gravity to speed up load movement.

For example, loaders such as those described above are often used to load loose materials by pushing packets along the ground to contain such materials.

On uneven ground it is desirable for the packet to follow this terrain, and the float position of the control system allows the packet to do this.

Until now, float position in fluid motor control systems has been limited to the structures required to configure the other motor operating modes described above, plus the complexities of the directional control valve, such as additional lands on the main spool and appropriate flow passages in the valve body. It was given by the structure of

This significantly increases the length of the directional control valve spool and the complexity of the valve body.

Directional control valves often require large assembly configurations,
Conventional provision for these float positions also increases the cost of such valves and also significantly increases the space requirements for control system setup in manufacturing bulk.

The object of the present invention is to provide a drive state and a hold state to operate the motor in either direction.

The object of the present invention is to provide a more compact and economical device for controlling a fluid motor in which it is desired to provide a float condition in addition to the above.

The object of the present invention is to cause motor operation in one direction by feeding pressurized fluid into the first motor suction/discharge port for a fluid motor having first and second motor suction/discharge ports; A control device that causes a motor to operate in the opposite direction by supplying pressurized fluid to a second motor suction/discharge port, the control device having an injection path for receiving the pressurized fluid, and further having an injection path for receiving the pressurized fluid, and further has an injection path for receiving the pressurized fluid, and further has an injection path for receiving the pressurized fluid, and a discharge passage communicating with the tank and first and second discharge passages connected to each other; The first pipe will be connected to the discharge channel.
between a motor operating position and a second motor operating position in which pressurized fluid from the injection passage is transmitted to the second discharge passage and at the same time the first discharge passage is communicated with the discharge passage; a directional control valve having a movable valve member and further having a pair of spring chambers for receiving guide fluid to move the valve member between the first and second motor operating positions; a control valve disposed in a detour passage between at least one of the discharge passages and the discharge passage, an open position allowing fluid communication through the detour passage and an open position blocking communication through the detour passage; a replenishment valve member movable between positions and a chamber communicating with the one discharge passage through an orifice, the fluid pressure obtained from the one discharge passage being applied to the replenishment valve member; a replenishment valve operative to place the valve member in the closed position; an inlet passage for receiving guide fluid; a discharge passage communicating with the tank; a pair of discharge passages communicating with the spring chamber of the directional control valve, and further having a float position movable between a plurality of operating positions for selectively transmitting the guide fluid to the directional control valve. a guide valve having a valve member movable to the valve member, and in the float position of the valve member, a pressure reducing passage communicates the chamber of the replenishment valve with a discharge passage of the guide valve such that the replenishment valve member A control device characterized in that the replenishment valve member is movable to the open position by fluid pressure in the discharge passage acting on an end or fluid pressure in one of the discharge passages acting on a shoulder of the replenishment valve member. achieved by.

The present invention is a compact and economically manufacturable device for the control of fluid motors provided with a float mode of operation and equipped with a make-up valve to suppress cavitation.

Rather than extending and complicating the directional control valve spool and body to provide a float position, the present invention utilizes replenishment valve means for this purpose.

In particular, by manually moving the guide valve controlling the directional control valve to the float setting position by the operator, the pressure which normally forces the replenishment valve into the closed condition is adjusted to be reduced.

At this time, the replenishment valve opens and both intake and exhaust terminals q< of the motor are communicated with each other, creating a floating state.

The motor is smaller, lower profile and more efficient by providing four modes of operation for the motor, such as by utilizing a directional control valve spool that only needs to have three positions to create a float condition. A control system can be configured.

Other objects and advantages of the invention will become apparent from the following description of preferred embodiments, taken in conjunction with the accompanying drawings.

Reference will first be made to the accompanying drawings, particularly FIG. 1.

The linear fluid motor 10 controlled by the invention is of conventional design and is therefore shown schematically in the drawings.

A pair of such motors 10 may be used, for example, to raise and lower packets in a loader vehicle of the type described above.

However, it should be understood that the present control system is not limited to this use case, nor is it limited to linear fluid motors, but can also be applied to rotary motors.

This type of linear motor 10 is supplied with a working fluid 2
It is provided with two fluid intake and discharge ports 11 and 12.

When working fluid is supplied to one port 11 of such intake/discharge ports, the motor moves backward and the fluid is discharged from the other port 12.

Also, when the working fluid is supplied through the suction/discharge port 12, the motor performs a forward stroke while the fluid is discharged through the other port 11.

The pressurized fluid that drives the motor 10 is supplied by a pump 13 that pumps fluid from a liquid tank 14 .

The outlet of the pump 13 is connected to the directional control valve 17 by a conduit 15.
The inlet 16 is connected to the inlet 16 of the inlet.

A safety valve 18 is connected between the conduit 15 and the reservoir 14 for determining the maximum fluid pressure that can be transmitted to the motor 10 and for returning excess fluid directly to the reservoir.

Directional control valve 17 includes a first valve member or spool 19 disposed within first bore 21 of valve body 22 .

This spool 19 is in a hold position when the motor 10 is stopped, a retracted position when the motor is driven in the direction R shown by the arrow 23, and a reverse position when the motor is driven in the reverse direction E shown by the arrow 23. It is possible to move axially into one of three positions, each comprising a third or forward position.

The spool 19 of the valve 17 is biased to a central position constituting a hold position by a pair of springs 2424a located at opposite ends of the spool within the bore 21.

The fluid injection port 16 communicates with an annular injection groove 61 in the center of the inner hole 21 via an injection path 59 .

The inner hole 21 is provided with another groove 71 on one side of the injection groove 61 at a distance from the injection groove 61, and this groove 71 communicates with the motor insertion port IH via a valve body discharge path 69 and a conduit 67. are doing.

Similarly, a groove 63 is formed on the other side of the central injection groove 61 through the inner hole 2.
1 is provided, and this groove 63 is communicated with the motor intake/discharge port 12 via a valve body discharge path 64 and a conduit 66.

Furthermore, the inner hole 21 is provided with separate grooves 73 and 77 on the outside of the grooves 71 and 63, respectively.
7 is communicated with the liquid tank 14 through a discharge passage 74 and a discharge pipe 76 in the valve body 22 .

The spool 19 is provided with a pair of grooves 62, 72 at both ends of the central land 19/ of the spool.

Therefore, when the spool 19 is in the above-mentioned center position or hold position, the land 1q blocks the driving fluid from both the motor suction and discharge ports 11 and 12, and at the same time, both ends of the spool connect the two motor suction and discharge ports and the discharge passage 74. communication is also cut off.

The motor 10 is thus stopped and cannot move forward or backward.

If the spool 19 is moved to the left in FIG.
At the same time, the motor suction and discharge port 11 is communicated with the discharge pipe 76 by the groove 72 of the spool, and the forward stroke of the motor 10 is caused.

Similarly, when the spool 19 is moved in the opposite direction, the driving fluid is sent from the inlet 16 to the motor suction/discharge 111 via the groove 72 of the spool, and at the same time, the motor suction/discharge port 12 is communicated with the discharge pipe 76 by the groove 62. A backward stroke of the motor is caused.

The spool 19 is moved between the three positions described above to control the motor 10 in response to a fluid pressure signal provided via a guide valve 25 which is manually controlled.

The guide valve 25 has a valve body 30 with an inner bore 32 .

A valve member or spool 31 is disposed within the bore 32 and is movable in the axial direction between four positions: forward, hold, backward, and float by an operator.

This guide valve 25 pumps up fluid from the liquid tank 14 and is connected to the conduit 2.
Pressurized fluid is supplied by a second pump 26 which flows to the inlet 28 via 7.

A second safety valve 29 is connected between conduit 27 and reservoir 14 for defining a reference guide fluid pressure and for returning excessive discharge of pump 26 to reservoir 14 .

The injection port 28 of the guide valve 25 is communicated with an annular injection groove 58 in the inner hole 32 by a valve body injection passage 56 .

Further, other grooves 34 and 43 are arranged on both sides of this groove 58, and discharge passages 33 and 42 of the guide valve 25 are disposed, respectively.
0 are connected.

These discharge passages 33.42 are respectively connected by conduits 49.53 to the respective inlets (
spring chamber) 51.54.

Further grooves 36, 45 are provided in the bore 32 of the guide valve 25 on the outside of the grooves 34 and 43, respectively.

The groove 36 communicates with the liquid tank 14 via a discharge path 37,
On the other hand, the groove 45 communicates with the liquid tank 14 via a discharge path 46.

The spool 31 has two grooves 35 formed at intervals.
44, and when the spool 31 is in the hold position, these grooves 35, 4j communicate the grooves 34, 43 with the discharge grooves 36, 45, respectively, while the spool 31
Communication between the injection port 58 and both the grooves 34 and 43 is cut off by the middle portion of the groove.

Therefore, when the guide valve 25 is in the hold position, the spring chambers 52 and 55 of the directional control valve 17 are both in the discharged state, and the directional control valve is set in the hold position in which the motor 10 is stopped.

As shown in FIG. 2, when the spool 31 of the guide valve 25 is moved to the forward position by the operator, the guide pressure from the inlet 28 is applied through the groove 58° 44.43 and the discharge passage 42. is transmitted to the conduit 53, while the conduit 49 is led to the liquid reservoir 14 via the discharge channel 33, the groove 34.35.36 and the discharge channel 37.

To explain with reference to FIG. 1 again, at this time the directional control valve 1
7 spring chamber 55 force S'jJIIIE, while spring chamber 5
2 is in the discharge state.

The spool 19 of the directional control valve 17 is therefore moved to the aforementioned position in which the motor 10 produces a forward stroke.

When the spool 31 of the guide valve 25 is manually moved to the retracted position shown in FIG. On the other hand, the conduit 53 includes the discharge path 42 and the groove 43,
It is communicated with the liquid tank 14 via 44 and 45.

Referring again to FIG. 1, this operation pressurizes the spring chamber 52 of the directional control valve 17, while the spring chamber 55 enters the discharge state.

The spool 19 of the directional control valve 17 is therefore moved to the aforementioned position in which the motor 10 performs a reverse stroke.

Considering the means for controlling cavitation of the motor 10, the direction control valve 17 is provided with a pair of cylindrical replenishment valve members 78, 79, and these replenishment valve members 78, 79 are connected to the valve body 22. are arranged in two holes 83, 83a so as to be movable in the axial direction.

The replenishment valve member 78 is pressed against the base 8H by a spring 86.

Through this pedestal portion 81, a hole 83 is formed as a short flow path (detour flow path) 7.
5, further communicates with the groove 73, and therefore the discharge passage 741
This is also connected.

Similarly, in the hole 83a, the replenishment valve member 79 is connected to the spring 86a.
is pressed against the pedestal 82 by the pedestal 82.
Through the hole 83a, the hole 83a communicates with the flow path (detour flow path) 75a, and further communicates with the groove 77 and the discharge path 74.

Therefore, the holes 83 and 83a are each normally connected to the supply valve member 7.
8 and 79 block communication with the discharge path.

However, by moving either of these replenishment valve members away from the associated pedestal 81 or 82, the associated hole and motor inlet will be brought into communication with the discharge passage 74.

Spring chamber 8 is provided by an orifice 85 located on the side of replenishment valve member 78 adjacent shoulder 87 thereof.
4 communicates with the motor inlet 11 via a discharge passage 69, and an orifice 102 is also provided in the replenishment valve member 79 at a position adjacent to the shoulder 103, thereby reducing the fluid pressure in the discharge passage 64. is transmitted to the spring chamber 88.

The areas of the replenishment valve member 78, 79 which receive the pressure in the spring chambers 84 and 88 are the shoulders 87, on which the pressure acts in opposite directions.
103, the valve members will normally remain closed despite pressure increases in the associated discharge passages 69 and 64, except under certain conditions described below.

As described above, while the motor is operated in the backward mode, the driving fluid is supplied to the intake/discharge port IH of the motor 10.

In this state, the discharge path 69 of the directional control valve 17 is pressurized,
On the other hand, the discharge path 64 is communicated with the liquid tank 14 .

If an external load force is applied to the motor 10 at this time, causing a retraction stroke faster than the retraction velocity provided by the drive fluid entering the motor 10 through the discharge passage 69, the pressure drop will pass through the orifice 85 of the make-up valve member 78. This occurs inside the discharge channel 69 that communicates with the spring chamber 84 .

At the same time, the pressure rises inside the discharge passage 64, and the discharge passage 7
4 to the detour flow path 75.

Therefore, the replenishment valve member 78 is pushed up against the spring force of the spring 86 and separated from the associated seat 81.

The pressure drop in the fluid in the discharge passageway 69 causes the fluid in the spring chamber 84 to enter the discharge passageway 69 through the orifice 85 of the replenishment valve member 78 .

Although the bypass passage 75 communicates with the liquid reservoir 14, as soon as the initial cavitation of the motor 10 reduces the pressure in the spring chamber 84 sufficiently, sufficient pressure is diverted to lift the replenishment valve member 78 from its seat. The bypass passage 75 and the liquid tank 1 should be sufficiently restricted so that the passage 75I appears.
4 constitutes a flow tube T6.

The replenishment valve used in the present invention is of conventional construction and has been in use for many years.

It is well known to those skilled in the art that such replenishment valves are opened by a pressure difference between the outlet and outlet channels.

This pressure difference is caused by a combination of the following two facts.

One is that when gravity acts and the fluid motor operates at a faster rate than the fluid acting on it, a negative pressure is created in the discharge passage.

This negative pressure is also communicated behind the replenishment valve members 78, 79 via orifices 85,102.

Also, when gravity is acting on a fluid motor, the motor tends to act like a pump forcing fluid flow through the exhaust passage.

Resistance to fluid flow through the valve's internal passages and circuits tends to create positive pressure within the drain passage.

The combination of these two actions is sufficient to move the replenishment valve member 78,79 to the open position.

When the replenishment valve member 78 is pushed up from the pedestal 81 as described above, the supply of driving fluid flowing into the motor intake/discharge port 11 via the discharge path 69 is the discharge fluid that is discharged from the other side of the motor 10. This is supplemented by additional fluid l from line 74.

The net effect of the replenishment valve member 78 is therefore to provide a direct exchange of fluid between the two intakes and outlets of the valve 10 when cavitation suppression is required.

The other replenishment valve member 79 is automatically opened to suppress cavitation in the forward travel of motor 10 in a manner essentially similar to that described above for replenishment valve member 78.

The conventional The system requires additional grooves on the spool 19 and in the bore 21 and additional flow paths in the valve body 22 to provide additional locations for the spool 19 of the directional control valve 17.

The present invention provides a fluid prepressure so that the replenishment valve member 78 is normally held closed, and selectively opens the replenishment valve member 78 when the guide fftlJfl valve spool 31 is manually moved to the float setting position. By configuring the structure, the increase in complexity, size, and cost of the directional control valve 17 as described above is avoided.

In the absence of such a fluid preload in the spring chamber 84, the make-up valve member 78 is adapted to provide an exchange of fluid between the two intake and outlet ports 11 and 12 of the motor in response to external load forces acting on the motor. It will be lifted from the related pedestal 81.

Considering now a suitable construction for this purpose, if the guide casing 25 is moved to a floating position as shown in FIG. 4, the guide pressure from the inlet 28 will be
This is communicated to the directional control valve 17 in a manner similar to that described above for the retracted position of the guide valve adjacent to this float position.

Referring again to FIG. 1, pressure from inlet 28 is transmitted via conduit 49 to spring chamber 52 of directional control valve 17, which causes control valve spool 19 to direct drive fluid to motor inlet/outlet 11. Motor intake and exhaust port 1
2 is moved to a position where it communicates with the liquid tank 14.

However, unlike the retracted position, in the float position of the guide valve 25 a further groove 9 in the inner bore 32 of the guide valve
1 communicates with the discharge channel 37/l via a further groove 89 on the guide valve spool 31.

Groove 91 is connected to float valve 93 by passage 92 and conduit 94.
is connected to.

Float valve 93 is further connected to spring chambers 84 and 88 by respective conduits 95 and 99, respectively.

Float valve 93 is comprised of a two-position valve having an internal spool 106 and a valve body 104 preloaded by a spring 107 to a position such that conduit 94 is in communication with conduit 99 and isolated from conduit 95. has been done.

Whenever the pump 26 supplies fluid pressure, the fluid pressure from the groove 58 of the manual guide valve 25 is transmitted to one end of the float valve 93 through the guide path 108, and the spool 106 is moved to a position different from the slave position. be done.

In this position, conduit 95 communicates with conduit 94 while conduit 99 is blocked, as shown in FIG.

Next, FIGS. 1 and 4 will be explained.

When the manual guide valve 25 is moved to the float position and the float valve 93 is held in another position by the guide pressure from the pump 26, the spring chamber 84 is connected to the conduit 95, the valve 93
, conduit 94 , grooves 91 and 36 , and discharge passage 37 to the discharge pipe.

In other words, the grooves 36, 91 and the conduit 95
A depressurizing passage is formed for communicating the spring chamber 84 with the discharge passage 37 of the guide valve when the valve moves to the float position.

In the state where the spring chamber 84 and the discharge passage 37 are in communication as described above, the replenishment valve member 78 responds to the fluid pressure in the detour flow passage 75 transmitted via the discharge passage 74 or the discharge passage acting on the shoulder portion 87. The pressure within 69 causes it to be lifted from the associated pedestal 81.

This is because the bias of spring 86 is the only force acting on replenishment valve portion 78 to hold it in the closed position.

In practice, this results in directional control valve inlet 16 and outlet 74
and the motor's binocular outlets 11, 12 are interconnected to form the desired floating state of the system.

At this time, when an external load force is applied to the motor 10, the motor 10 can freely move in both directions.

Achieving the float position as described above ~ Here, pump 2
It will be appreciated that it is necessary for the directional control valve spool 19 to be moved against the spring force of the spring 24a by the guide fluid pressure from the guide valve 25 generated by the guide valve 25.

Thus, during operation of the pump 26, the float valve 93 is always switched, thereby providing a float position during normal operation of the device.

However, motor 10 is often supporting a load such as a loader packet.

If pumps 13 and 26 fail for some reason, it is often desirable to lower the load to the ground.

Since the spool 19 of the main control valve is actuated by guide pressure, such operation would not be possible without the float valve 93.

When pump 26 is not operating, float valve 93 is moved by spring force to a position where conduit 99 communicates with groove 91 of the guide valve, as shown in FIG.

At this time, when the guide valve 25 is moved to the float position shown in FIG. 4, the spring chamber 88 is brought into the discharged state.

In the discharge state of the spring chamber 88, fluid pressure in the channel 64 acting on the shoulder 103 causes the valve member 79 to unseat, so that the fluid in the discharge channel 64 passes through the channel 77 to the liquid reservoir 10.
Leads to 4.

Although the invention has been described with respect to one preferred embodiment ζ, many modifications can be made without departing from the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing a fluid motor and its control device according to the invention, the valve body being shown in cross-section, the other elements shown schematically, and the control device being shown in the hold or neutral position. It is shown in 2 is a cross-sectional view of the guide valve portion of FIG. 1 shown moved to an advanced position in which the motor is operated in a first direction; FIG. FIG. 3 shows the guide valve moved to a retracted position in which the motor is operated in the opposite direction. FIG. 4 is a sectional view showing the guide valve moved to the float position. 10: Fluid motor, 11, 12: Motor intake and exhaust port, 17:
Directional control valve, 19, 31: Valve member, 25: Guide valve, 7
B, 79: Supply valve member, 93: Float valve.

Claims (1)

[Claims] 1. For a fluid motor 10 having first and second motor suction and discharge ports 11 and 12, motor operation in one direction is achieved by supplying pressurized fluid to the first motor suction and discharge ports. The control device causes the motor to operate in the opposite direction by causing pressurized fluid to flow into the second motor intake/discharge port, and further includes an injection path 59 for receiving the pressurized fluid, and further includes an injection path 59 for receiving the pressurized fluid, The first and second motors are connected to two motor intake and exhaust ports, respectively.
a discharge passageway 69,64 and a discharge passageway 74 communicating with the tank, the pressurized fluid from the injection passageway being communicated with the first discharge passageway and the second discharge passageway communicating with the discharge passageway; a first motor operating position in which the first motor is in operation, and a second motor operating position in which the first discharge passage is communicated with the discharge passage at the same time that pressurized fluid from the injection passage is communicated to the second discharge passage; a valve member 19 movable between the first and second motor operating positions, and a spring chamber 51 dimensioned for receiving guide fluid to move the valve member between the first and second motor operating positions. a directional control valve 17 having a diameter of 54°; and a directional control valve 17 disposed in a detour passage 75 between at least one of the discharge passages of the directional control valve and the discharge passage; It has a replenishment valve member 78 that is movable between an open position that allows communication and a closed position that blocks communication through the bypass flow path, and a chamber 84 that communicates with the one discharge path via an orifice 85. a replenishment valve in which fluid pressure obtained from the one discharge passage acts on the replenishment valve member to force it into the closed position; an injection passage 56 for receiving guide fluid; and a discharge passage 37 communicating with the tank; a pair of discharge passages 33, 42 communicating with the spring chamber of the directional control valve for transmitting the guide fluid for moving the valve member of the directional control valve; a guide valve 25 having a valve member 31 movable between a plurality of operating positions and also movable to a float position for selectively transmitting the guide fluid to the valve;
1 float position, pressure reducing passage 35,91°95
communicates the chamber of the replenishment valve with the discharge passage of the guide valve, thus reducing fluid pressure in the discharge passage 74 acting on the end of the replenishment valve member or in one of the discharge passages acting on the shoulder 87 of the replenishment valve member. A control device characterized in that the replenishment valve member is movable to the open position by fluid pressure.