JPH0511220B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic pump and a hydraulic pump installed in a fluid machine.
It relates to hydraulic pump/motor devices such as motors.

[Conventional technology]

Figures 4 and 5 show a swash plate type hydraulic pump/motor device as an example of a conventional hydraulic pump/motor device.
4 is a cross-sectional view of the motor, and FIG. 5 is a front view of the distribution valve portion corresponding to the - arrow direction in FIG. 4.

In FIGS. 4 and 5, reference numeral 1 indicates a casing, and a rotary shaft 3 is rotatably supported by the casing 1 via a bearing 2. 4 represents a cylinder block, which is connected to the rotating shaft 3 by a spline 3A;
It rotates together with this rotating shaft 3. Further, the cylinder block 4 is aligned along its axial direction and with respect to the rotating shaft 3.
It has multiple cylinders 5 built in surrounding it.
A piston 6 is provided within these cylinders 5 so as to be able to reciprocate. The right end of each piston 6 in FIG. It reciprocates within 5. Reference numeral 7 indicates a distribution valve interposed between the casing 1 and the cylinder block 4. One side of the distribution valve 7 is in close contact with the casing 1, and a pin 8 interposed therebetween allows the distribution valve 7 to connect to the casing 1. Fixed. This distribution valve 7 has a pair of elongated suction and discharge ports 9 and 10, as illustrated in FIG.
It is constantly in communication with suction and exhaust passages 11 and 12 formed in the. Then, when the cylinder block 4 rotates,
The intake and exhaust ports 9 and 10 are connected to the cylinder block 4.
It is intermittently connected to a passage 5A that communicates with each cylinder 5 provided in the cylinder. Note that 14a and 14b are notches formed at the ends of the suction and discharge ports 9 and 10.

If the hydraulic pump/motor configured as described above is used as a hydraulic pump, the operation will be as follows.

First, when the rotating shaft 3 is driven, the cylinder block 4, which is spline-coupled to the rotating shaft 3, rotates integrally. At this time, the piston 6 provided in the cylinder 5
Since one end of the piston 6 is supported by a swash plate (not shown), the piston 6 reciprocates within the cylinder 5 when the cylinder block 4 rotates. Here, if port 9 of the suction and exhaust ports 9 and 10 is used as the suction port and port 10 is used as the discharge port, the piston 6 is It moves in the direction of extension and enters a suction stroke in which hydraulic oil is sucked into the cylinder 5 from the port 9. Then, when the piston 6 passes its bottom dead center and begins to enter (contract) into the cylinder 5, the cylinder 5 switches to a state in which port 9 communicates with the port 10, and the piston 6 causes the operation inside the cylinder 5 to start. The oil is pressurized and the hydraulic oil is discharged from the port 10 in a discharge stroke. Furthermore, when the piston 6 reaches its top dead center and starts to extend again, the cylinder 5 is moved to the port 9.
This communicates with the pump to form a suction stroke, and the pump action is performed by repeating the suction stroke and discharge stroke in this way.

[Problem that the invention seeks to solve]

By the way, in the case of this conventional hydraulic pump/motor, during the above-mentioned pump operation, at the bottom dead center and the top dead center, the cylinder and the suction/exhaust ports 9, 10 suddenly change from low pressure to high pressure or from high pressure to low pressure. Easily changeable. In order to alleviate such a phenomenon, measures are taken to gradually increase or decrease the pressure within the cylinder 5 using the notches 14a and 14b. However, when the set pressure or rotation speed changes, this conventional hydraulic pump/motor cannot appropriately increase or decrease the pressure inside the cylinder 5, and therefore the solid line in Fig. 6 The pressure inside the cylinder becomes as shown, and a surge pressure as exemplified by point A is likely to occur at the bottom dead center, and an abnormal negative pressure as exemplified by the point B is likely to occur at the top dead center. As a result, the discharge pressure also
This results in large pressure pulsations as shown by the solid line in the figure, causing an increase in noise and
The fluid machine equipped with the motor is likely to be damaged due to the pressure pulsation.

The present invention was made in view of the actual situation in the prior art, and its purpose is to create a hydraulic pressure system that can appropriately increase or decrease the cylinder internal pressure even when the set pressure or rotation speed changes. The purpose of the present invention is to provide a pump motor device.

[Means for solving problems]

In order to achieve this object, the present invention has a communication path that is provided between the intake and exhaust ports of the distribution valve, that can communicate with the cylinder of the cylinder block, and that can also communicate with the tank, and a rotating shaft that rotates the cylinder block. a small-capacity pump having an input shaft driven by the pump and capable of communicating with the communication passage; a first switching valve interposed in a first passage that communicates the small-capacity pump with the communication passage; , a second switching valve interposed in a second passage connecting the communication passage and the tank; an internal pressure detector for detecting the internal pressure of the cylinder in the cylinder block via the communication passage; A port pressure detector that detects the pressure of the port, and a control means that selectively operates the first and second switching valves according to the pressure value of the internal pressure detector and the pressure value of the port pressure detector. It is configured.

[Effect]

Since the present invention is configured as described above, the control means compares, for example, the pressure value of the internal pressure detector and the pressure value of the port pressure detector, and when the cylinder changes from the direction of expansion to the direction of contraction. When the pressure value of the port pressure detector that detects the pressure of the discharge port of the suction/discharge ports is larger than the pressure value of the internal pressure detector, the control means controls the control means to connect the communication passage and the small-capacity pump. The switching valve 1 is switched to increase the pressure inside the cylinder and prevent the generation of surge pressure. Also, when the cylinder changes from the direction of contraction to the direction of expansion, the pressure of the internal pressure detector is changed. When the pressure value of the port pressure detector that detects the pressure of the suction port among the suction and exhaust ports is smaller than the pressure value, the control means switches the second switching valve so as to connect the communication passage with, for example, a tank; This reduces the pressure inside the cylinder to prevent abnormal negative pressure from occurring.

〔Example〕

Hereinafter, the hydraulic pump/motor device of the present invention will be explained based on the drawings.

FIGS. 1 to 3 are explanatory diagrams showing one embodiment of the present invention, and show a swash plate type hydraulic pump/motor corresponding to those shown in FIGS. 4 and 5 described above.
Figure 1 is a schematic diagram of the overall configuration, Figure 2 is a cross-sectional view showing the casing, distribution valve, and cylinder block, and Figure 3 is a front view of the distribution valve section corresponding to the - arrow direction in Figure 2. be.

First, the casing 1 and the distribution valve 7 portion will be explained with reference to FIGS. 2 and 3. In this embodiment, as particularly illustrated in FIG. Communication passages 15a, 15b are provided in each of the lower portions, and these communication passages 15a, 15b can communicate with the cylinder 5 of the cylinder block 4, as will be described later. Furthermore, the casing 1 is provided with passages that are always in communication with the communication passages 15a and 15b, of which passage 1 communicates with the communication passage 15b.
Only 6b is shown for convenience. That is, this casing 1 is also provided with a passage that communicates with the communication passage 15a, although not shown. The other configurations of the casing 1, distribution valve 7, and cylinder block 4 are the same as those shown in FIGS. 4 and 5 described above, for example.

Further, 18a and 18b shown in FIG. 1 are internal pressure detectors that detect the internal pressure of the cylinder 5 built in the cylinder block 4 via the above-mentioned communication passages 15a and 15b, and 21a and 21b are the pressures of the suction and exhaust ports 9 and 10. This is a port pressure detector that detects Also, 2
5 has an input shaft driven by the rotating shaft 3 that rotates the cylinder block 4, and has a communication path 15a,
15b is a small capacity pump, such as a hydraulic pump, 26 is a pressure control valve that regulates the discharge pressure of this hydraulic pump 25, and 27 is a tank. 17b
17d is a first switching valve interposed in the first passage 20a that connects the communication passage 15a and the hydraulic pump 25, such as a high-speed electromagnetic valve that operates ON-OFF; and 17d, the communication passage 15b and the hydraulic pump 25 are connected A first switching valve, for example a high speed solenoid valve, is interposed in the first passage 20b. Further, 17a is a second switching valve, for example, a high-speed solenoid valve, which is interposed in a second passage 19a (including a passage not shown provided in the casing 1) that connects the communication passage 15a and the tank 27, and 17c is a communication valve. A second switching valve, for example, a high-speed solenoid valve, is interposed in a second passage 19b (including passage 16b provided in casing 1) that communicates passage 15b and tank 27.

Further, 24 is a control means, and this control means 24 includes the aforementioned internal pressure detectors 18a, 18b, port pressure detectors 21a, 21b, and high-speed solenoid valve 17.
a, 17b, 17c, 17d are connected,
The control means 24 appropriately operates the high-speed solenoid valves 17a to 17d according to the pressure values of the internal pressure detectors 18a and 18b and the pressure values of the port pressure detectors 21a and 21b.

The operation of this embodiment when used as a hydraulic pump will be described below.

When the rotating shaft 3 shown in FIG. 2 is driven, the hydraulic pump 25 is driven and the cylinder block 4 is rotated integrally. Along with this, piston 6
reciprocates inside the cylinder 5, but if we now assume that the suction/discharge port 9 is the suction port and the suction/discharge port 10 is the discharge port, from the suction stroke of the hydraulic oil in which the cylinder 5 communicates with the port 9, the cylinder 5 moves to the port 10.
During the transition to the discharge stroke of the hydraulic oil that communicates with the third
As illustrated in the figure, a passage 5A communicating with the cylinder 5 communicates with a communication passage 15a, whereby the internal pressure of the cylinder 5 is detected by the internal pressure detector 18a.
This detected pressure value is used as a signal by the control means 24.
The control means 24 compares this pressure value with the pressure value of the port 10 output from the port pressure detector 21b. When the pressure value of the port 10 is larger than the pressure value of the internal pressure detector 18a, a drive signal is output to the high-speed solenoid valve 17b.
In response, the high-speed solenoid valve 17b is switched from the block position shown in FIG. 1 to the right position, and the hydraulic pump 25
The pressure oil of the hydraulic pump 25 is guided to the communication passage 15a via the passage 20a and a passage of the casing 1 (not shown), and the pressure inside the cylinder 5 is increased. This prevents a sudden pressure change from low pressure to high pressure, that is, the pressure inside the cylinder 5 changes smoothly from low pressure to high pressure.

Furthermore, when the cylinder 5 transitions from the discharge stroke in communication with the port 10 to the suction stroke in which the cylinder 5 communicates with the port 9, the passage 5A communicating with the cylinder 5 is connected to the communication passage 1.
5b, whereby the internal pressure of the cylinder 5 is detected by the internal pressure detector 18b. This detected pressure value is sent as a signal to the control means 24, and the control means 24 compares this pressure value with the pressure value of the port 9 output from the port pressure detector 21a. When the pressure value of the port 9 is smaller than the pressure value of the internal pressure detector 18b, the high-speed solenoid valve 1
A drive signal is output to 7c. In response, the high-speed solenoid valve 17c is switched from the block position shown in FIG.
It is led to the tank 27 via the passage 16b and passage 19b of the casing 1, and the pressure inside the cylinder 5 is reduced.
This prevents a sudden pressure change from high pressure to low pressure, that is, the pressure inside the cylinder 5 changes smoothly from high pressure to low pressure.

In addition, in the above, the suction/exhaust port 9 was set as the suction port, and the suction/exhaust port 10 was set as the exhaust port.
The suction/exhaust port 9 is used as a discharge port, and the suction/exhaust port 10
When setting the suction port, the control means 24
is the high-speed solenoid valve 1 when the pressure value of the port pressure detector 21a is larger than the pressure value of the internal pressure detector 18b.
7d to the left position in FIG. 1 to connect the communication passage 15b and the hydraulic pump 25 via the passage 20b, and when the pressure value of the port pressure detector 21b is smaller than the pressure value of the internal pressure detector 18a. 1, switch the high-speed solenoid valve 17a to the left position in FIG.
The communication path 15a and the tank 27 are communicated through the a. In this way, similar to the above, sudden pressure changes within the cylinder 5 are prevented.

In the embodiment configured in this way, even if the set pressure or rotation speed changes, the communication path 15 can be adjusted as appropriate.
Cylinder 5 and hydraulic pump 25 via a, 15b
Alternatively, since it communicates with the tank 27, it is possible to appropriately increase or decrease the pressure within the cylinder 5. Therefore, the pressure within the cylinder 5 increases as shown by the broken line in FIG. The pressure becomes stable without generating surge pressure or negative pressure, and along with this, the discharge pressure also becomes a relatively gentle pressure pulsation as shown by the broken line in FIG.

〔Effect of the invention〕

Since the hydraulic pump/motor device of the present invention is configured as described above, it is possible to appropriately increase or decrease the pressure inside the cylinder even if the set pressure or rotation speed changes. This eliminates the generation of surge pressure or negative pressure, and the discharge pressure becomes a gentler pressure pulsation than before, suppressing noise and preventing damage to the liquid machine equipped with the hydraulic pump/motor due to the pressure pulsation. There is an effect that can be done.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory diagrams showing one embodiment of the hydraulic pump/motor device of the present invention. Figure 1 is a schematic diagram of the overall configuration, and Figure 2 is a casing, distribution valve, and cylinder block portion. FIG. 3 is a front view of the distributing valve portion corresponding to the - arrow direction in FIG. 2, and FIGS.
4 is a cross-sectional view, FIG. 5 is a front view of the distribution valve portion corresponding to the - arrow view in FIG. 4, and FIG. 6 is an explanatory view showing an example of a motor device.
An explanatory diagram comparing the rotation angle-in-cylinder pressure characteristics of a motor device and a hydraulic pump/motor device of the present invention, and Fig. 7 shows a comparison between a conventional hydraulic pump/motor device and a hydraulic pump/motor device of the present invention. It is an explanatory diagram showing a comparison of rotation angle-discharge pressure characteristics of the device. 1...Casing, 4...Cylinder block, 5...
Cylinder, 5A... Passage, 6... Piston, 7... Distribution valve, 9, 10... Suction/exhaust port, 15a, 15b... Communication path, 16b, 19a, 19b... Second passage, 2
0a, 20b...first passage, 17a...high speed solenoid valve (second switching valve), 17b...high speed solenoid valve (first switching valve), 17c...high speed solenoid valve (second switching valve), 1
7d...High speed solenoid valve (first switching valve), 18a, 1
8b... Internal pressure detector, 21a, 21b... Port pressure detector, 24... Control means, 25... Hydraulic pump (small capacity pump), 27... Tank.

Claims (1)

[Claims] 1. A casing having a suction and discharge passage, a distribution valve connected to the casing and having a suction and discharge port communicating with the suction and discharge passage, and a distribution valve connected to the distribution valve,
In the hydraulic pump/motor device, the hydraulic pump/motor device includes a cylinder block that is rotatably provided and includes a plurality of cylinders each having a passageway communicating with the suction/exhaust port, and a rotating shaft for rotating the cylinder block. A small-capacity motor, which is provided between the suction and exhaust ports of the cylinder, has a communication passage that can communicate with the cylinder and can also communicate with the tank, and an input shaft driven by the rotation shaft, and can communicate with the communication passage. a pump, a first switching valve interposed in a first passage communicating between the small capacity pump and the communication passage, and a second passage interposed in a second passage communicating between the communication passage and the tank. a second switching valve, an internal pressure detector that detects the internal pressure of the cylinder in the cylinder block via the communication path, a port pressure detector that detects the pressure of the suction/exhaust port, and a pressure value of the internal pressure detector. and a control means for selectively operating the first and second switching valves according to the pressure value of the port pressure detector.