JP3080597B2 - Pump flow control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device for a hydraulic pump or the like used in a construction machine or the like, in which a regulator for electrically controlling horsepower and flow is mounted.

[0002]

2. Description of the Related Art A conventional electric control regulator hydraulic circuit is shown in FIGS. 21 (a) and 22 (a). FIG.
The electric control regulator hydraulic circuit shown in FIG.
As shown in (b), when the current I increases, the flow rate Q increases, and has a positive flow control characteristic called “positive control”. As shown in FIG. 22B, the electric control regulator hydraulic circuit shown in FIG. 22A has a negative flow control characteristic called “negative control” as the current I increases and the flow rate Q decreases.

An electric control regulator 1 having a positive control characteristic shown in FIG. 21 is provided for controlling the capacity of a variable displacement hydraulic pump 2 in accordance with a current I flowing to an electromagnetic proportional valve 3. The electric control regulator 1 includes a servo switching valve 4 and a servo cylinder 5, and can change the displacement by changing the tilt angle of the swash plate 6 of the variable displacement hydraulic pump 2. Servo switching valve 4 includes a spool 7 and a sleeve 8. The spool 7 is urged by a spring 9 in the direction in which the discharge capacity of the variable displacement hydraulic pump 2 decreases, and the discharge capacity of the variable displacement hydraulic pump 2 is controlled by a control side piston 10 which receives the secondary pressure from the electromagnetic proportional valve 3. Are biased in the increasing direction. Sleeve 8 is connected rod 11
Is mechanically connected to the servo piston 12 in the servo cylinder 5 via the.

In the electric control regulator 13 having a negative control characteristic shown in FIG. 22, when the control side piston 10 presses and moves the spool 15 of the servo switching valve 14, the discharge capacity of the variable displacement hydraulic pump 2 decreases.

[0005] The electric control hydraulic circuit as shown in FIGS. 21 and 22 can be controlled, for example, as shown in FIG. 23 by program-controlling the electromagnetic proportional valve 3 by a computer. Prior art regarding electrical control of a hydraulic pump is disclosed in, for example, Japanese Patent Laid-Open No. 3-138468.

[0006]

In a flow control device of a hydraulic pump for performing electric control as shown in FIGS. 21 and 22,
If an abnormality occurs in the electric control system such as the electromagnetic proportional valve 3 or the computer, the operation of the construction machine or the like becomes impossible, or the operation speed becomes extremely slow. JP-A-3-13
In the prior art of 8468, various sensors detect the operation state of the hydraulic pump and the like, and perform an electric feedback control to achieve a stable operation. When a malfunction occurs in the feedback signal detection system, the feedback unit is shut off. Is shown. However, if an abnormality occurs in the electromagnetic proportional valve 3 or the computer itself, it is difficult to perform open loop control. The electromagnetic proportional valve 3 may have a possibility that the winding may be broken due to high-temperature exhaust gas from the engine that drives the hydraulic pump 2 with a variable displacement.

It is an object of the present invention to be able to use the electric control system without deteriorating its operability even if an abnormality occurs.
An object of the present invention is to provide a pump flow control device which can easily switch between electric control and hydraulic control.

[0008]

The present invention provides an electromagnetic proportional valve,
A servo switching valve and a servo cylinder are provided. The secondary pressure from the solenoid proportional valve causes the spool of the servo switching valve to be displaced in the direction of increasing or decreasing the displacement of the variable displacement pump. The servo piston is displaced, and the volume of the variable displacement pump is changed in conjunction with the servo piston, and feedback is performed by the displacement of the spool of the servo switching valve. In a flow control device of a pump for increasing or decreasing a discharge flow rate, a secondary side of an electromagnetic proportional valve for applying a control fluid pressure to a primary side and an increasing side pressure receiving portion for urging a spool of a servo switching valve in a capacity increasing direction. Between the solenoid proportional valve and the
The control-side redundant switching valve, which can manually switch between a state in which the next pressure is guided and a state in which the primary control fluid pressure is guided, and the capacity decreasing direction of the spool of the discharge side of the variable displacement pump and the servo switching valve. Discharge-side redundancy provided between the pressure-reducing portion and the pressure-reducing portion, which is capable of manually switching between a state in which the pressure-reducing portion is blocked and a condition in which the discharge pressure of the variable displacement pump is guided to the pressure-reducing portion. And a switching valve for the pump. According to the present invention, there is provided a positive control type flow control device for increasing a discharge flow rate from a variable displacement pump in accordance with an increase in a proportional current to an electromagnetic proportional valve, wherein an increasing side for urging a spool of a servo switching valve in a capacity increasing direction. The secondary pressure from the electromagnetic proportional valve or the primary control fluid pressure is switched and guided to the pressure receiving portion via the control-side redundant switching valve. The discharge-side pressure of the variable displacement pump can be guided to the decreasing-side pressure receiving portion that urges the spool in the capacity decreasing direction by switching the discharge-side redundant switching valve. In the normal state, the secondary pressure from the electromagnetic proportional valve is guided to the increasing side pressure receiving portion of the spool via the control-side redundant switching valve, and the electromagnetic proportional valve is electrically controlled using a computer or the like, and the variable displacement pump is controlled. Can be electrically controlled. Since the control-side redundant switching valve and the discharge-side redundant switching valve can be manually switched, when the electric control system is abnormal, the primary-side switching valve is connected to the increasing-side pressure receiving portion of the spool via the control-side redundant switching valve. The control fluid pressure can be guided, and the discharge side pressure of the variable displacement pump can be guided to the decreasing pressure receiving portion of the spool via the discharge side redundancy switching valve, so that horsepower control can be manually switched.

The present invention further includes an electromagnetic proportional valve, a servo switching valve, and a servo cylinder, and displaces a spool of the servo switching valve in a direction of increasing or decreasing the displacement of the variable displacement pump by a secondary pressure from the electromagnetic proportional valve. , The servo piston in the servo cylinder is displaced by the output from the servo switching valve,
The change in the volume of the variable displacement pump and the feedback of the displacement of the spool of the servo switching valve are linked with the servo piston to increase or decrease the discharge flow from the variable displacement pump by increasing or decreasing the command current to the solenoid proportional valve. In a flow rate control device of a pump to be controlled, a secondary side of an electromagnetic proportional valve for providing a control fluid pressure to a primary side and an increasing or decreasing pressure receiving portion for urging a spool of a servo switching valve in a capacity increasing or decreasing direction. A secondary pressure from the electromagnetic proportional valve to the increasing or decreasing pressure receiving portion, and a primary control fluid pressure from the increasing or decreasing pressure receiving portion to the control valve of the servo switching valve. A switching valve for redundancy capable of manually switching between a state in which pilot control fluid pressure is guided to a decreasing pressure receiving section or an increasing pressure receiving section for urging the spool in a capacity decreasing direction or a capacity increasing direction, The spool corresponding pressure servo switching valve to discharge pressure from the variable displacement pump, a flow control device of the pump characterized in that it urges the capacity decreasing direction. According to the present invention, with the positive control type flow control device, the switching valve for redundancy is manually switched, and the control fluid pressure on the primary side is guided to the increasing pressure receiving portion of the spool of the servo switching valve, and the decreasing pressure receiving portion is provided. To the state where the pilot control fluid pressure is guided to
When the pressure corresponding to the discharge pressure from the variable displacement pump is urged in the direction of decreasing the capacity of the spool, a combination of the flow rate control and the horsepower control can be performed.

The present invention further includes an electromagnetic proportional valve, a servo switching valve, and a servo cylinder, and displaces a spool of the servo switching valve in a direction of increasing or decreasing the displacement of the variable displacement pump by a secondary pressure from the electromagnetic proportional valve. The servo piston in the servo cylinder is displaced by the output from the servo switching valve, and the displacement of the volume of the variable displacement pump and feedback by the displacement of the spool of the servo switching valve are performed in conjunction with the servo piston. In a pump flow control device that reduces or increases the discharge flow rate from a variable displacement pump by increasing or decreasing the command current of the variable displacement pump, a decreasing side pressure that urges the discharge side of the variable displacement pump and the spool of the servo switching valve in the capacity decreasing direction. And a state in which the pressure-reducing pressure-receiving part is blocked and a state in which the discharge pressure of the variable displacement pump is guided to the pressure-reducing pressure-receiving part. A manual flow rate control device of the pump characterized in that it comprises a switchable redundant switching valve a. According to the present invention, the negative control type electric control in which the current to the electromagnetic proportional valve increases and the flow rate of the variable displacement pump decreases, and the capacity of the servo switching valve spool is reduced by switching the redundant switching valve. Horsepower control by fluid pressure can be performed by guiding the discharge pressure of the variable displacement pump to the decreasing-side pressure receiving portion biased in the direction. Thus, when an abnormality occurs in the electrical control system, the operation by the fluid pressure control can be performed by manually switching the redundant switching valve.

The present invention further includes an electromagnetic proportional valve, a servo switching valve, and a servo cylinder, and displaces a spool of the servo switching valve in a direction of increasing or decreasing the displacement of the variable displacement pump by a secondary pressure from the electromagnetic proportional valve. Then, the servo piston in the servo cylinder is displaced by the output from the servo switching valve, and in response to the servo piston, the change in the volume of the variable displacement pump and feedback by the displacement of the spool of the servo switching valve are performed. In a pump flow control device for decreasing or increasing the discharge flow rate from a variable displacement pump by increasing or decreasing a command current to the pump, a secondary side of an electromagnetic proportional valve for providing a control fluid pressure to a primary side and a servo switching valve An electromagnetic proportional valve is provided between the increasing or decreasing pressure receiving portion that urges the spool in the direction of increasing or decreasing the capacity. A state in which the secondary pressure is guided and a state in which the pilot control fluid pressure is guided to the pressure-increasing or decreasing-side pressure receiving portion, which includes a switching valve for redundancy, which corresponds to the discharge pressure from the variable displacement pump. A pressure control device for a pump, wherein pressure urges a spool of a servo switching valve in a capacity decreasing direction. According to the present invention, a flow control device for electrically controlling a negative control type in which a flow rate of a variable displacement pump is reduced when a command current of an electromagnetic proportional valve is increased. The pilot control fluid pressure is guided to the pressure-reducing pressure receiving part that urges the spool in the capacity decreasing direction, thereby controlling the flow rate by the pilot control fluid pressure and the pressure corresponding to the discharge pressure from the variable displacement pump. And the horsepower control by urging the spool in the capacity decreasing direction.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Portions corresponding to those described earlier are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 shows a regulator hydraulic circuit according to a first embodiment of the present invention. This embodiment corresponds to claim 1
Corresponding to the invention according to the above. The electric control regulator 21 shown in FIG. 1A controls the volume of the variable displacement hydraulic pump 22 by
Positive control is performed so that it increases when the command current to the electromagnetic proportional valve 23 increases.

The electric control regulator 21 includes a servo switching valve 24 and a servo cylinder 25. The servo cylinder 25 is a swash plate 2 of the variable displacement hydraulic pump 22.
The displacement is controlled by changing the tilt angle of No. 6. In the servo switching valve 24, the spool 27 and the sleeve 28 can reciprocate independently in the axial direction. Spool 2
7 is urged by the pilot spring 29 to the decreasing side where the discharge capacity of the variable displacement hydraulic pump 22 is minimized. In a normal electric control system, the control-side piston 30 receives the secondary pressure from the electromagnetic proportional valve 23 and urges the spool 27 to the increasing side in which the discharge capacity of the variable displacement hydraulic pump 22 increases. . The connecting rod 3 moves so that the sleeve 28 moves following the movement of the spool 27.
1 through the servo piston 32 in the servo cylinder 25
Mechanically connected to The servo piston 32 is also connected to the swash plate 26 of the variable displacement hydraulic pump 22, and changes the tilt angle as described above.

A control-side redundant switching valve 33 is provided between the pressure receiving portion of the control-side piston 30 and the secondary side of the electromagnetic proportional valve 23. A compensating piston 34 abuts on the other end of the spool 27 opposite the one end in the axial direction with which the control-side piston 30 abuts. The discharge pressure of the variable displacement hydraulic pump 22 can be guided to the compensating piston 34 via a discharge-side redundant switching valve 35. The control-side redundant switching valve 33 and the discharge-side redundant switching valve 35 are configured as shown in FIG.
Switching between the normal side shown in FIG. 1A and the redundant side shown in FIGS. 1B and 1C is possible. The control-side redundant switching valve 33 is formed in the solenoid valve main body block 36 of the solenoid proportional valve 23. The discharge pressure Pd of the variable displacement hydraulic pump 22 and the control hydraulic pressure Psv of the primary side of the electromagnetic proportional valve 23
Are connected to the servo switching valve 24 and the discharge-side redundant switching valve 35 via the check valve 37 and the check valve 38, respectively.
To the primary side of

FIG. 1B shows that the control side redundant switching valve 33 is switched to the redundant side, and the primary pressure P to the primary side of the electromagnetic proportional valve 23 is changed.
sv is directly given to the control side piston 30, and the electromagnetic proportional valve 23
The secondary pressure indicates a state of blocking. The spool 27 is
Since it is urged by the pilot spring 29 to the decreasing side, when the secondary pressure from the electromagnetic proportional valve 23 becomes zero, it moves to the fully closed position. In the present embodiment, the control hydraulic pressure Psv is applied to the pressure receiving portion of the control side piston 30 to enable the horsepower control. FIG. 1C shows a switching valve 3 for the discharge side redundancy.
5 shows a state where the discharge pressure Pd of the variable displacement hydraulic pump 22 is guided to the compensating piston 34 by switching 5 to the redundant side. When the discharge pressure Pd increases, the spool 27 moves to the decrease side, and the discharge capacity decreases, so that the engine for driving the variable displacement hydraulic pump 22 can be prevented from being stalled.

FIG. 2 shows the horsepower control characteristics of the flow rate Q corresponding to the discharge pressure Pd when the control-side redundant switching valve 33 and the discharge-side redundant switching valve 35 are switched to the redundant side. For example, when the maximum horsepower characteristic of the engine that drives the variable displacement hydraulic pump 22 is indicated by a broken line, when the discharge pressure Pd increases, the spool 27 is moved to the capacity decreasing side, and the flow rate Q becomes the maximum horsepower characteristic. Horsepower control can be performed to reduce so as not to exceed the limit.

FIG. 3 shows the electric control regulator 21 of FIG.
1 shows a cross-sectional configuration. The state of the control-side redundant switching valve 33 and the discharge-side redundant switching valve 35 is the normal side shown in FIG. The aforementioned check valves 37 and 38 are formed in the regulator body block 40. The discharge pressure Pd of the variable displacement hydraulic pump 22 is introduced from the discharge pressure passage 41 to the primary side of the servo switching valve 24 via the check valve 37. The oil passage 42 that guides the discharge pressure Pd to the pressure receiving portion of the compensating piston 34 is connected to the valve body 4 of the discharge-side redundant switching valve 35.
Blocked by 3. If the valve body 43 of the discharge side redundant switching valve 35 is moved to the redundant side by the screw 44, the discharge pressure Pd can be applied to the compensating piston 34. The secondary pressure of the electromagnetic proportional valve 23 is guided to the pressure receiving portion of the control piston 30 via the oil passage 45. If the position of the valve body 46 of the control-side redundant switching valve 33 is moved by the screw 47, the control hydraulic pressure Psv applied to the primary pressure input port 48 can be directly guided to the oil passage 45.

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. The control hydraulic pressure Psv given to the primary pressure input port 48 is supplied to the electromagnetic proportional valve 23 via an oil passage 49.
To the primary side. The secondary pressure of the electromagnetic proportional valve 23 is guided from the oil passage 50 to the oil passage 45 communicating with the pressure receiving portion of the control piston 30 through the passage of the valve body 45 of the control-side redundant switching valve 33.

FIG. 5 shows a state in which the control-side redundant switching valve 33 is switched to the redundant side. FIG. 5A shows the direction shown in FIG.
FIG. 5B shows a state viewed from the direction shown in FIG. The secondary pressure from the electromagnetic proportional valve 23 is supplied to the oil passages 50 and 45.
Since the space is blocked by the valve body 46, the pressure is not applied to the pressure receiving portion of the control-side piston 30. In the oil passage 45,
The control hydraulic pressure Psv is guided from the primary pressure input port 48 via a passage formed in the valve body 46 and is supplied to the pressure receiving portion of the control-side piston 30.

FIG. 6 shows a second embodiment of the present invention.
2 shows a hydraulic circuit of a negative control type electric control regulator 51. This embodiment corresponds to the invention according to claim 3. FIG. 6A shows that the discharge side redundant switching valve 35 is on the normal side.
(B) shows a state on the redundant side, respectively. The spool 57 of the servo switching valve 54 is
Since the discharge pressure of the variable displacement hydraulic pump 22 is increased, the servo switching valve 54 is fully opened when the secondary pressure from the electromagnetic proportional valve 23 becomes zero. Therefore, it is not necessary to apply the primary control hydraulic pressure Psv to the control-side piston 30 as in the embodiment of FIG. When the spool 57 of the servo switching valve 54 is pressed by the control side piston 30, the spool 57 moves to the side where the discharge capacity of the variable displacement hydraulic pump 23 decreases. In the present embodiment, horsepower control having characteristics as shown in FIG. 7 can be performed on the redundant side using only the discharge side redundant switching valve 35.

FIG. 8 shows a third embodiment of the present invention.
3 shows a hydraulic circuit of a positive control type electric control regulator 61. This embodiment corresponds to the invention according to claim 2, in which a redundant switching valve 63 is formed in the solenoid valve main block 36 of the solenoid proportional valve 23. FIG. 8 shows a state where the redundant switching valve 63 is on the normal side. Spool 27 of servo switching valve 24
And a horsepower control side lever 65 for urging the flow control lever toward the increasing side and the decreasing side. The flow control lever 64 receives an increasing force from the control piston 30 and a decreasing force from the pilot pressure piston 66 and the spring 67. Horsepower control side lever 65
Receives a decreasing force from the horsepower control piston 68 and an increasing force from the spring 69. A secondary pressure from the electromagnetic proportional valve 23 is applied to the pressure receiving portion of the control-side piston 30.
Positive control flow control can be performed.

When the redundant changeover valve 63 is switched to the redundant side, the control hydraulic pressure Psv is applied to the horsepower control piston 68 on the side where the discharge capacity is reduced, and the control hydraulic pressure is applied to the control side piston 30 from the electromagnetic proportional valve 23. Secondary pressure is blocked. A pilot pressure Pp from the outside is applied to the pressure receiving portion of the pilot pressure piston 66, and presses the spool 27 to the side where the discharge capacity decreases.

FIG. 9 shows control characteristics according to the embodiment of FIG. FIGS. 9A and 9B show the horsepower control characteristics and the flow control characteristics on the normal side, respectively. FIG. 9 (c),
(D) shows the reduced horsepower control characteristic and the flow control characteristic on the redundant side, respectively. In this embodiment, the pilot pressure Pp is changed by changing the function of the redundant switching valve 63.
Posicon-type flow rate control based on JIS is also possible.

FIG. 10 shows a hydraulic circuit of a positive control type electric control regulator 71 as a fourth embodiment of the present invention. This embodiment corresponds to the invention according to claim 2,
A horsepower control-side lever 65 provided for urging the spool 27 of the servo switching valve 24 to the decreasing side receives the decreasing force from the piston 72 for decreasing horsepower and the piston 73 for increasing horsepower.
And an increasing force from the spring 74. On the normal side of the redundant switching valve 63, a secondary pressure from the electromagnetic proportional valve 23 is applied to the pressure receiving portion of the control side piston 30, so that a positive control type flow control can be performed.

When the redundant switching valve 63 is switched to the redundant side, the hydraulic pressure for control Psv on the increasing side of the displacement is blocked in the piston 73 for horsepower. The secondary pressure from the electromagnetic proportional valve 23 is blocked and the control hydraulic pressure Psv is supplied to the pressure receiving portion of the control piston 30. The pilot pressure piston 66 receives a pilot pressure P from the outside.
is given, and the spool 27 is pressed toward the side where the discharge capacity decreases.

FIG. 11 shows control characteristics according to the embodiment of FIG. FIGS. 11A and 11B show the horsepower control characteristic and the flow control characteristic on the normal side, respectively. FIG.
(C) and (d) show the horsepower control characteristic and the flow control characteristic on the redundant side, respectively. In this embodiment, by changing the function of the redundant switching valve 63, a positive control flow rate control based on the pilot pressure Pp is also possible.

FIG. 12 shows a hydraulic circuit of a negative control type electric control regulator 81 as a fifth embodiment of the present invention. This embodiment corresponds to the invention according to claim 4,
A switching valve 83 for redundancy is formed in the solenoid valve block 36 of the solenoid proportional valve 23. In FIG. 12, the switching valve 83 for redundancy is
Indicates a state on the normal side. In order to urge the spool 57 of the servo switching valve 54 to the decreasing side, the flow control side lever 6
4 and a horsepower control side lever 65 are provided. The flow control lever 64 receives a decreasing force from the control piston 30 and an increasing force from the spring 67. The horsepower control side lever 65 receives a decreasing force from the horsepower reducing piston 72, and receives an increasing force from the horsepower increasing piston 73 and the spring 74. A secondary pressure from the electromagnetic proportional valve 23 is applied to the pressure receiving portion of the control side piston 30, so that a negative control type flow control can be performed.

When the redundant switching valve 83 is switched to the redundant side, the hydraulic pressure Psv for increasing the discharge capacity is blocked at the pressure receiving portion of the horsepower increasing piston 73. The secondary pressure from the electromagnetic proportional valve 23 is blocked from being applied to the pressure receiving portion of the control-side piston 30, and an external pilot pressure Pn is applied to press the spool 57 to the side where the discharge capacity is reduced.

FIG. 13 shows control characteristics according to the embodiment of FIG. FIGS. 13A and 13B show the horsepower control characteristics and the flow control characteristics on the normal side, respectively. FIG.
(C) and (d) show a horsepower control characteristic and a flow control characteristic on the redundant side, respectively. In this embodiment, by changing the function of the switching valve 63 for redundancy and adding a pilot piston to the spring 67 side, the pilot pressure Pn
Posicon-type flow rate control based on JIS is also possible.

FIG. 14 shows a hydraulic circuit of a negative control type electric control regulator 91 as a sixth embodiment of the present invention. This embodiment corresponds to the invention according to claim 4. A redundant switching valve 93 is formed in the solenoid valve main body block 36 of the solenoid proportional valve 23. In the present embodiment, the horsepower control side lever 65 provided for urging the spool 57 of the servo switching valve 54 toward the decreasing side receives the decreasing force from the horsepower control piston 68, and the increasing force from the spring 69. Receive. On the normal side of the switching valve 93 for redundancy, the secondary pressure from the electromagnetic proportional valve 23 is applied to the pressure receiving portion of the control side piston 30, so that a negative control type flow control can be performed.

When the redundant switching valve 93 is switched to the redundant side, the horsepower control piston 68 is supplied with the control hydraulic pressure Psv on the side where the discharge capacity decreases. The secondary pressure from the electromagnetic proportional valve 23 is blocked from being applied to the pressure receiving portion of the control-side piston 30, and an external pilot pressure Pn is applied to press the spool 57 to the side where the discharge capacity is reduced. Thus, FIG.
The fourth embodiment is a negative control based on the redundancy time Pn. When the function of the switching valve 63 for redundancy is changed and a pilot piston is added to the spring 67 side, positive control of the flow rate of the positive control by Pn becomes possible.

FIG. 15 shows control characteristics according to the embodiment of FIG. FIGS. 15A and 15B show the horsepower control characteristics and the flow control characteristics on the normal side, respectively. FIG.
(C) and (d) show the reduced horsepower control characteristic and the flow control characteristic on the redundant side, respectively. In this embodiment, a negative control type flow rate control based on the pilot pressure Pn is also possible.

FIG. 16 shows an electric control regulator 101 capable of negative-flow control based on a pilot pressure Pn as shown in FIG. 14 as a seventh embodiment of the present invention.
2 shows a configuration in which two sets of variable displacement hydraulic pumps 22a and 22b driven by one engine are controlled in tandem using two sets of a and 101b. In this embodiment, as in FIG.
This corresponds to the invention according to claim 4. The engine also drives the control hydraulic power source 102. The horsepower control piston 108 of one electric control regulator 101a has
Not only the discharge pressure Pd and the control hydraulic pressure Psv, but also the discharge pressure Pd from the variable displacement hydraulic pump 22b controlled by the other electric control regulator 101b is given.

FIGS. 17 and 18 show examples of the configurations of the horsepower control unit and the flow control unit, respectively. FIGS. 19 and 20 show a state where the redundant switching valve 93 is on the normal side and the redundant side, respectively, as viewed from the cutting plane line IXX-IXX of FIG. The redundant switching valve 93 blocks the oil passage 110 communicating with the pressure receiving portion of the horsepower control piston 108 on the normal side, and supplies the control hydraulic pressure on the primary side of the electromagnetic proportional valve 23 on the redundant side. It communicates with 111. Further, the space between the pilot pressure input port 112 and the oil passage 113 communicating with the pressure receiving portion of the control-side piston 30 is blocked on the normal side, and is communicated on the redundant side. Such switching is performed by moving the position of the valve element 116 with the screw 117.

In the embodiment described above, although the redundant switching valve switches between the normal side and the redundant side with a relatively large stroke displacement using a screw, another mechanism known as a valve structure is used. It can also be used. With a simple structure using a screw, reliable and reliable operation can be expected without erroneous switching.

[0037]

As described above, according to the present invention, in the positive control type flow control device, the electrical control and the mechanical control are performed by manually controlling the control-side redundant switching valve and the discharge-side redundant switching valve. Can be changed over. Thus, even if an abnormality occurs in the electric control system, horsepower control can be performed to prevent the variable displacement pump from operating beyond its limit and to stall the driving engine.

Further, according to the present invention, the electric control system and the fluid pressure control system can be switched by manually switching the redundant switching valve in a flow control device having a positive control type control characteristic. In the state where the control mode is switched to the fluid pressure control system, the flow control and the horsepower control based on the pilot control fluid pressure can be performed with good operability.

Further, according to the present invention, the electric control system and the fluid pressure control system can be easily switched by manually switching the redundant switching valve in the flow control device having a negative control type control characteristic. Horsepower control can be performed even if the control system becomes abnormal.

Still further, according to the present invention, the electric control system and the fluid pressure control system can be easily switched by manually switching the redundant switching valve in a flow control device having a negative control type control characteristic. . In the state switched to the fluid pressure control system, the control can be performed with good operability by combining the flow control with the pilot control fluid pressure and the horsepower control.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a first embodiment of the present invention.

FIG. 2 is a graph showing horsepower control characteristics of the embodiment of FIG.

FIG. 3 is a sectional view of a regulator in which the hydraulic circuit of the embodiment of FIG. 1 is incorporated.

FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3;

FIG. 5 is a cross-sectional view showing a state where the control-side redundant switching valve 33 of FIG. 3 is switched to a redundant side.

FIG. 6 is a hydraulic circuit diagram according to a second embodiment of the present invention.

FIG. 7 is a graph showing a horsepower control characteristic of the embodiment of FIG. 6;

FIG. 8 is a hydraulic circuit diagram according to a third embodiment of the present invention.

FIG. 9 is a graph showing control characteristics of the embodiment of FIG.

FIG. 10 is a hydraulic circuit diagram according to a fourth embodiment of the present invention.

FIG. 11 is a graph showing control characteristics of the embodiment of FIG.

FIG. 12 is a hydraulic circuit diagram according to a fifth embodiment of the present invention.

FIG. 13 is a graph showing control characteristics of the embodiment of FIG.

FIG. 14 is a hydraulic circuit diagram according to a sixth embodiment of the present invention.

FIG. 15 is a graph showing control characteristics of the embodiment of FIG.

FIG. 16 is a hydraulic circuit diagram according to a seventh embodiment of the present invention.

17 is a cross-sectional view of a horsepower control unit of a regulator incorporating the hydraulic circuit of FIG.

FIG. 18 is a cross-sectional view of a flow control unit incorporating the hydraulic circuit of the embodiment of FIG.

FIG. 19 is a cross-sectional view taken along section line IXX-IXX in FIG. 18;

20 is a cross-sectional view showing a state in which the switching valve for redundancy 93 in FIG. 19 is switched to a redundant side.

FIG. 21 is a hydraulic circuit diagram of a conventional positive control type electric control regulator and a graph showing flow control characteristics thereof.

FIG. 22 is a hydraulic circuit diagram of a conventional negative control type electric control regulator and a graph showing flow control characteristics thereof.

FIG. 23 is a graph showing an example of a characteristic of horsepower control enabled by computer control of the electric control regulator shown in FIGS. 21 and 22.

[Explanation of symbols]

21, 51, 61, 71, 81, 91, 101a, 10
1b Electric control regulator 22, 22a, 22b Variable displacement hydraulic pump 23 Electromagnetic proportional valve 24, 54 Servo switching valve 25 Servo cylinder 26 Swash plate 27, 57 Spool 28 Sleeve 29 Pilot spring 30 Control piston 31 Connecting rod 32 Servo piston 33 Control-side redundant switching valve 34 Compensation piston 35 Discharge-side redundant switching valve 41 Discharge pressure passage 42, 45, 49, 50, 110, 111, 113 Oil passage 46, 116 Valve element 47, 117 Screw 63, 83, 93 Redundancy Switching valve 64 Flow control side lever 65 Horsepower control side lever 66 Pilot pressure piston 68,108 Horsepower control piston 72 Piston for horsepower reduction 73 Piston for horsepower increase

────────────────────────────────────────────────── (5) References JP-A-3-138468 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04B 49/00-51/00 F15B 13 / 043

Claims (4)

(57) [Claims] 1. A servo switching device comprising an electromagnetic proportional valve, a servo switching valve, and a servo cylinder, wherein a secondary pressure from the electromagnetic proportional valve displaces a spool of the servo switching valve in a direction of increasing or decreasing the displacement of a variable displacement pump. The servo piston in the servo cylinder is displaced by the output from the valve, and the change in the volume of the variable displacement pump and the feedback by the displacement of the spool of the servo switching valve are performed in conjunction with the servo piston,
A pump flow control device for increasing or decreasing a discharge flow rate from a variable displacement pump by increasing or decreasing a command current to an electromagnetic proportional valve, comprising: a secondary side of an electromagnetic proportional valve for providing a control fluid pressure to a primary side;
A state in which the secondary pressure from the electromagnetic proportional valve is provided between the servo pressure control valve and the increasing pressure receiving portion that urges the spool of the servo switching valve in the capacity increasing direction; A control-side redundant switching valve that can manually switch between a state in which the pump is guided, and a reducing-side pressure receiving portion that urges the discharge side of the variable displacement pump and the spool of the servo switching valve in the capacity decreasing direction, A flow control of a pump, comprising: a discharge-side redundant switching valve capable of manually switching between a state in which the pressure-reducing part is reduced and a state in which the discharge pressure of the variable displacement pump is guided to the pressure-receiving part. apparatus. 2. A servo switching system comprising a proportional solenoid valve, a servo switching valve and a servo cylinder, wherein a secondary pressure from the solenoid proportional valve displaces a spool of the servo switching valve in a direction of increasing or decreasing the displacement of the variable displacement pump. The servo piston in the servo cylinder is displaced by the output from the valve, and the change in the volume of the variable displacement pump and the feedback by the displacement of the spool of the servo switching valve are performed in conjunction with the servo piston,
A pump flow control device for increasing or decreasing a discharge flow rate from a variable displacement pump by increasing or decreasing a command current to an electromagnetic proportional valve, comprising: a secondary side of an electromagnetic proportional valve for providing a control fluid pressure to a primary side;
A state in which a secondary pressure from an electromagnetic proportional valve is provided between an increasing or decreasing pressure receiving section that urges a spool of a servo switching valve in a capacity increasing or decreasing direction, and an increasing or decreasing pressure receiving section; The primary control fluid pressure is guided to the pressure receiving portion or the decreasing pressure receiving portion, and the pilot control fluid is supplied to the decreasing pressure receiving portion or the increasing pressure pressure receiving portion for urging the spool of the servo switching valve in the capacity decreasing direction or the capacity increasing direction. A switching valve for redundancy capable of manually switching between a pressure guiding state and a pressure corresponding to the discharge pressure from the variable displacement pump urges the spool of the servo switching valve in a capacity decreasing direction. Pump flow control device. 3. A servo switching device comprising an electromagnetic proportional valve, a servo switching valve, and a servo cylinder, wherein a secondary pressure from the electromagnetic proportional valve displaces a spool of the servo switching valve in a direction of increasing or decreasing the displacement of the variable displacement pump. The servo piston in the servo cylinder is displaced by the output from the valve, and the change in the volume of the variable displacement pump and the feedback by the displacement of the spool of the servo switching valve are performed in conjunction with the servo piston,
In a pump flow control device that reduces or increases the discharge flow rate from a variable displacement pump by increasing or decreasing the command current to an electromagnetic proportional valve, the discharge side of the variable displacement pump and the spool of the servo switching valve are urged in the capacity decreasing direction. And a redundant switching valve that is provided between the pressure-reducing unit and the pressure-reducing unit that can manually switch between a state in which the pressure-reducing unit is blocked and a state in which the discharge pressure of the variable displacement pump is guided to the pressure-reducing unit. A flow control device for a pump. 4. A servo switching device comprising an electromagnetic proportional valve, a servo switching valve, and a servo cylinder, wherein a secondary pressure from the electromagnetic proportional valve displaces a spool of the servo switching valve in a direction of increasing or decreasing the displacement of the variable displacement pump. The servo piston in the servo cylinder is displaced by the output from the valve, and the change in the volume of the variable displacement pump and the feedback by the displacement of the spool of the servo switching valve are performed in conjunction with the servo piston,
A pump flow control device for decreasing or increasing the discharge flow rate from a variable displacement pump by increasing or decreasing a command current to an electromagnetic proportional valve, comprising: a secondary side of an electromagnetic proportional valve for providing a control fluid pressure to a primary side;
A state in which the secondary pressure from the electromagnetic proportional valve is provided between the increasing or decreasing pressure receiving portion that urges the spool of the servo switching valve in the direction of increasing or decreasing the capacity; Includes a redundant switching valve that can manually switch between a state in which pilot control fluid pressure is guided to the pressure-reducing pressure receiving section, and the pressure corresponding to the discharge pressure from the variable displacement pump moves the spool of the servo switching valve to the capacity decreasing direction. A flow rate control device for a pump, characterized in that the flow rate is controlled to be positive.