JP3611615B2 - Electric control pump - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electric control pump that is used in various industrial fields and has a discharge flow rate variable by changing a tilt angle by a swash plate type or a tilt axis type, and performs feedback control by detecting the pump tilt angle. .
[0002]
[Prior art]
Conventionally, variable displacement type axial piston pumps have been widely used in various general industrial fields including construction machinery. In order to stably control the hydraulic pressure discharged from the pump, mechanical feedback is provided using a regulator. Control is often performed. With an electric control pump, the pressure and flow rate required for the load can be controlled quickly and with high accuracy by means of an electrical signal from a sequencer, etc., by electrically detecting and controlling the tilt angle of the pump controlled by the regulator. Is possible.
[0003]
FIG. 5 shows an external configuration of a typical conventional electric control pump. A regulator 2 is attached to the pump body 1. The pump is driven via the drive shaft 3. Inside the pump body 1, a swash plate 4 is disposed on the extension of the drive shaft 3. The regulator 2 changes the angle θ with respect to the direction perpendicular to the axis of the drive shaft 3 of the swash plate 4 and changes the discharge flow rate as a pump. This angle θ is called a tilt angle and is detected by the potentiometer 5 and converted into an electrical signal. The prior art for detecting the displacement of the variable element related to the tilt angle θ is disclosed, for example, in Japanese Utility Model Laid-Open No. 1-66483.
[0004]
FIG. 6 shows an attached state of the potentiometer 5. In the pump body 1, the cylinder block 6 is rotationally driven by the drive shaft 3 of FIG. A plurality of bores extending parallel to the axial direction of the drive shaft 3 and spaced apart in the circumferential direction are formed in the cylinder block 6, and the piston 7 is inserted therethrough. A piston shoe 8 is formed at the tip of the piston 7 and is coupled to a shoe plate 9 on the swash plate 4 side. The coupling angle is freely displaceable between the piston shoe 8 and the shoe plate 9.
[0005]
A mounting hole 11 and a mounting seat 12 for mounting the potentiometer 5 facing the swash plate 4 are formed in the casing 10 of the pump body 1. A cam 13 is provided on the rotation shaft of the potentiometer 5, and the displacement of the swash plate 4 is transmitted via the detection member 14 and the detection pin 15. The cam 13 converts the tilt of the swash plate 4 into a change in rotation angle and transmits the change to the potentiometer 5.
[0006]
FIG. 7 shows an example of a hydraulic circuit of the electric control pump shown in FIG. The pump 16 includes a pump body 1, a control valve 17, a servo piston 18, an electromagnetic proportional pressure reducing valve 19, a relief valve 20, a pressure detector 21, and the like. The tilt angle of the swash plate 4 is detected by a potentiometer 5. The discharge pressure from the pump body 1 is detected by a pressure detector 21. A relief valve 22 is provided so that the discharge pressure does not exceed the upper limit value. The control of the electromagnetic proportional pressure reducing valve 19 is performed by electrically feeding back the detection outputs from the potentiometer 5 and the pressure detector 21 by the control circuit 23.
[0007]
[Problems to be solved by the invention]
In the prior art as shown in FIGS. 5 to 7, a potentiometer 5 as a sensor is directly attached to the swash plate 4 in order to detect the tilt angle of the pump. Other prior art includes attaching a sensor to the servo piston 18 or the like. In order to attach the sensors to these variable elements, it is necessary to provide the pump body 1 with a special sensor, detection parts, a seat for attaching the sensor, and the like. As for hydraulic pumps, the ones that do not perform electrical feedback control are rather produced in quantity, and the parts that have been processed to add a configuration for electrical feedback control are It will be handled as a special product different from the standard product, and the manufacturing cost will increase.
[0008]
An object of the present invention is to provide an electric control pump capable of reducing the number of parts used and suppressing an increase in manufacturing cost.
[0009]
[Means for Solving the Problems]
The present invention includes a variable displacement pump main body and an electric control specification regulator, and a servo piston that changes the tilt angle of the pump main body and a regulator are connected by a swingable lever, and the discharge pressure is controlled by the regulator. In an electric control pump provided with a detection means for detecting a tilt angle for electrical feedback control of pressure and flow rate by an external control device while performing mechanical feedback control for stabilization,
The regulator can be replaced according to the required specifications for the pump body,
The electric control specification regulator is provided with the detecting means for detecting the tilt angle based on the swing angle displacement amount of the lever, and does not perform the electric feedback control and the electric feedback control. The electric control pump is characterized in that the pump body side is shared in some cases.
[0010]
[Action]
According to the present invention, the detecting means for detecting the tilt angle of the pump for performing the electric control by the external control device is the lever for performing the mechanical feedback control by the regulator of the electric control specification provided with the detecting means. The tilt angle is detected based on the swing angle displacement amount. The regulator can be exchanged according to various specifications of the pump, is smaller than the pump body, and is originally used by exchanging a plurality of types according to the specification. An increase in manufacturing cost can be suppressed by using a common pump body for the case where electrical feedback control is performed and the case where electrical feedback control is not performed. Since the detecting means detects the tilt angle according to the movement of the lever that swings and displaces due to mechanical feedback, it is not necessary to use a special part for detecting the tilt angle, and the number of parts can be reduced. it can.
[0011]
【Example】
1 shows a schematic configuration of an embodiment of the present invention, FIG. 2 shows a detailed configuration for detecting a tilt angle, FIG. 3 shows a simplified configuration of a hydraulic proportional control valve, and FIG. Shows a simplified configuration for mechanical feedback.
[0012]
In the present embodiment, a regulator 32 is attached to the upper part of the pump body 31 and can be replaced according to the required specifications. In the pump main body 31, a swash plate 34 inclined with respect to a plane perpendicular to the axis of the drive shaft 33 is accommodated, and the tilt angle θ is variable. The tilt angle θ is detected by a potentiometer 35 attached to the regulator 32.
[0013]
A cylinder block 36 is accommodated on the extension of the axis of the drive shaft 33 in the pump body 31. A plurality of bores parallel to the axial direction of the drive shaft 33 are formed in the cylinder block 36 at intervals in the circumferential direction. A piston 37 is inserted into the bore, and a spherical piston shoe 38 is formed at the tip thereof. The piston shoe 38 engages with a shoe plate 39 provided on the swash plate 34, and reciprocates the piston 37 in the bore of the cylinder block 36 in the axial direction as the cylinder block 36 rotates.
[0014]
As shown in FIG. 2, the regulator 32 that can be attached to and detached from the pump body 31 is formed with a mounting hole 41 and a mounting seat 42 for mounting the potentiometer 35 to the casing 41. Mechanical feedback by the regulator 32 is performed via a feedback lever 43. The displacement of the feedback lever 43 is transmitted to the potentiometer 35 by the detection member 44 and the detection pin 45. The detection member 44 is supported by a bearing 46. The potentiometer 35 detects an electrical signal as a change in resistance value of the magnetoresistive element without contact, or directly detects a change in resistance value as the contact slides on the resistor. Convert and take out.
[0015]
In the regulator 32, a hydraulic proportional control valve 47 on which pilot pressure acts is provided, and in the pump body 31, a hydraulic proportional control valve 47, a feedback lever 43, and a servo piston 48 that is linked via an oil passage are provided. The hydraulic proportional control valve 47 includes an outer sleeve 49 and an inner spool 50 that are independently movable in a direction perpendicular to the paper surface. The feedback lever 43 is supported on the casing 40 of the regulator 32 above the hydraulic proportional control valve 47 so as to be swingable and displaceable by a lever shaft 51. The feedback lever 43 and the sleeve 49 are connected via a feedback pin 52, and the feedback lever 43 and the servo piston 48 are connected via a feedback pin 53.
[0016]
When the servo piston 48 is displaced in the direction perpendicular to the paper surface of FIG. 2, the feedback lever 43 connected by the feedback pin 53 is oscillated and displaced about the lever shaft 51 in the direction perpendicular to the paper surface of FIG. The sleeve 49 is displaced in the direction perpendicular to the paper surface of FIG. Such a displacement of the feedback lever 43 is output as an electrical signal from the potentiometer 35 by angularly displacing the mounting member 44 via the detection pin 45.
[0017]
FIG. 3 shows the configuration of the hydraulic proportional control valve 47. The sleeve 49 and the spool 50 can be reciprocally displaced in the axial direction independently of each other. The spool 50 is pressed by the pilot pressure Pi from the left side of FIG. 3 and pressed by the spring 54 from the right side, and moves and displaces to a position where both forces are balanced. When the spool 50 is displaced relative to the sleeve 49, for example, to the right in FIG. 3, the control pressure Pr of the oil passage 49a approaches the pressure on the tank 50a side. As a result, the servo piston 48 is displaced, and the sleeve 49 follows the displacement of the spool 50 via the feedback lever 43. When the pilot pressure Pi decreases and the spool 50 is displaced to the left in FIG. 3, the control pressure Pr of the oil passage 49a approaches the pump discharge pressure Pd introduced from the port 49b and increases. As a result, the servo piston 48 is displaced, and the sleeve 49 is also displaced to the left via the feedback lever 43.
[0018]
As shown in FIG. 4, if the control pressure Pr on the large-diameter side of the servo piston 48 changes as a result of applying the pilot pressure Pi to the hydraulic proportional control valve 47, the balance of force with the discharge pressure Pd on the small-diameter side is achieved. Collapses. As a result, the servo piston 48 is displaced. This displacement causes the feedback lever 43 to swing and displace via the feedback pin 53, and provides mechanical feedback to the sleeve 49 via the feedback pin 52. When the sleeve 49 follows the spool 50 and the oil passage 49a closes, the mechanical feedback system stops. The displacement of the servo piston 48 changes the tilt angle θ of the swash plate 34 via the connecting member 55.
[0019]
In the embodiment described above, the position feedback method is used as the mechanical feedback, but a force feedback method may be used. Similarly, the displacement of the feedback lever in the regulator can be detected by a sensor such as a potentiometer, and the pump body 31 can be standardized and shared. Further, in the pump body 31, a variable displacement pump is realized by a swash plate type, but may be realized by an oblique axis type.
[0020]
【The invention's effect】
As described above, according to the present invention, the detection means is provided in the regulator of the electric control specification, and the pump main body side is shared between the case where the electric feedback control by the external control device is not performed and the case where the specification is performed. Therefore, the manufacturing cost can be reduced by the mass production effect. Furthermore, since the tilt angle is detected using components for mechanical feedback control, a dedicated component for tilt angle detection is unnecessary, and the component cost is reduced by reducing the number of necessary components. Reduction in manufacturing cost can also be achieved.
[Brief description of the drawings]
FIG. 1 is a simplified front view showing an external configuration of an embodiment of the present invention.
FIG. 2 is a partial side sectional view showing a configuration for detecting a tilt angle θ in the embodiment of FIG. 1;
3 is a simplified cross-sectional view showing the configuration of the hydraulic proportional control valve 47 of FIG.
FIG. 4 is a simplified front view showing a configuration for mechanical feedback in the embodiment of FIG. 1;
FIG. 5 is a simplified front view showing an external configuration of a conventional electric control pump.
6 is a partial plan sectional view showing a configuration for detecting a tilt angle in the electric control pump of FIG. 5. FIG.
7 is a hydraulic circuit diagram showing an example of the electric control pump of FIG. 5. FIG.
[Explanation of symbols]
31 Pump body 32 Regulator 33 Drive shaft 34 Swash plate 35 Potentiometer 36 Cylinder block 37 Piston 40 Casing 43 Feedback lever 44 Detection member 45 Detection pin 47 Hydraulic proportional control valve 48 Servo piston 49 Sleeve 50 Spool 51 Lever shaft 52, 53 Feedback pin 54 Spring 55 connecting member

Claims (1)

In order to stabilize the discharge pressure by connecting the servo piston that changes the tilt angle of the pump body and a regulator with a lever that can be swung and displaced, including a variable displacement pump body and a regulator with electrical control specifications. In the electric control pump provided with a detecting means for detecting the tilt angle for the electrical feedback control of the pressure and the flow rate by the external control device while performing the mechanical feedback control of
The regulator can be replaced according to the required specifications for the pump body,
The electric control specification regulator is provided with the detecting means for detecting the tilt angle based on the swing angle displacement amount of the lever, and does not perform the electric feedback control and the electric feedback control. An electric control pump characterized in that the pump body side is shared in some cases.

Images