JP2526407Y2 - Radial piston pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a radial piston pump used for driving a hydraulic device such as a hydraulic cylinder.

(Prior Art) A drive circuit for expanding and contracting a hydraulic cylinder is configured, for example, as shown in FIG. That is, the hydraulic pump 40
Of the hydraulic cylinder 43 via the check valve 41 and the pressure control valve 42
The relief valve 44 and the accumulator 45 are interposed in the middle of this. As the hydraulic pump 40, for example, a constant discharge type radial piston pump driven by a motor is used. In this case, since it is difficult to adjust the discharge flow rate of the hydraulic pump 40 on the motor side, the hydraulic pump 40 is always operated in a constant state, and the control of the hydraulic pressure supplied to the hydraulic cylinder 43 is performed by the pressure control valve 42. .

The accumulator 45 stores the discharge oil of the hydraulic pump 40 to supply a stable hydraulic pressure to the pressure control valve 42 and suppress a sudden change in the load of the hydraulic pump 40. The surplus of the discharge oil 40 is returned to the tank 34, and the check valve 41 prevents the backflow of the hydraulic oil from the accumulator 45 to the hydraulic pump 40.

However, in the actual operation of the hydraulic cylinder 43, most of the oil discharged from the hydraulic pump 40 is a relief valve.
Reflux from 44 to tank 34 results in hydraulic pump
Most of the 40 drive energy will be wasted unnecessarily. One of the ways to reduce such waste of energy is to increase the capacity of the accumulator 45,
Although miniaturization of the hydraulic pump 40 is required, the weight of the accumulator 45 increases, which causes another problem that a large space is required for the arrangement.

An object of the present invention is to provide a radial piston pump capable of easily adjusting a discharge flow rate in order to solve the above problems.

(Means for Achieving the Object) The present invention provides an eccentric cam fixed to a rotating shaft, a suction chamber for accommodating the eccentric cam, an oil chamber formed radially with respect to the rotating shaft, Equipped with a piston that reciprocates in the oil chamber following the eccentric cam, two pump units that discharge hydraulic oil sucked into the oil chamber from the suction chamber to the discharge passage with the reciprocation of the piston on the same rotating shaft And a passage communicating the discharge passage of one of the pump units with the suction chamber of the other pump unit, and a valve for opening and closing the passage. When the valve is opened, the suction of the other pump unit is performed. The piston of the pump unit is separated from the eccentric piston by the discharge pressure introduced into the chamber.

(Operation) In a state where the valve is closed, the two pump units are driven integrally by the rotation of the rotating shaft, and the discharge flow rates of both pumps are summed to become the pump discharge flow rate. When the valve is opened, the pressure oil discharged into the discharge passage of one pump unit is guided to the suction chamber of the other pump unit via the passage, and the piston is confined in the oil chamber at this high pressure and separated from the eccentric cam. . For this reason, in this pump unit, only the eccentric cam idles with respect to the rotation of the rotating shaft, the piston is not driven, and the hydraulic oil is not discharged. Therefore, the pump discharge flow rate is only the discharge amount of the other pump unit.

(Embodiment) Figs. 1 to 3 show an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a pump body. Suction chambers 2 and 3 are formed side by side inside the pump body 1, and a rotary shaft 4 passes through the suction chambers 2 and 3 so as to rotate freely.
The suction chambers 2 and 3 are hermetically sealed by seals 5 and 6 which are in sliding contact with the rotating shaft 4, and two pump units A and B are formed around the suction chambers 2 and 3.

The pump unit A is configured as follows. That is, an eccentric cam 8 is fixed to the rotating shaft 4 in the suction chamber 2, a plurality of oil chambers 9 are formed radially in the pump body 1 facing the suction chamber 2, and the piston inserted into the oil chamber 9 is formed. 10 slides freely into the suction chamber 2. The piston 10 is formed in a fixed cylindrical shape, is inserted into the hydraulic pressure 9 with the bottom portion directed toward the suction chamber 2, and is inserted into the suction chamber 2 by a spring 11 disposed in the oil chamber 8.
Biased in the direction. In addition, a suction port 12 for sucking hydraulic oil in the suction chamber 2 into the oil chamber 9 is opened on a side surface near the bottom.

The pump body 1 is provided with a suction port 17 communicating with a tank 34 shown in FIG.
It communicates with the suction chamber 2 via 13 and the orifice 14. Each oil chamber 9 is connected to a discharge passage 30 shown in FIG.

The pump unit B is formed around the suction chamber 3, and has the same eccentric cam 18, oil chamber 19, piston 2 as the pump unit A.
0, a spring 21, a suction port 22, a suction passage 23 communicating with the suction port 17, and an orifice 24 and a check valve 25 reaching the discharge passage 31. As shown in FIG. 2, the pump body 1 has a discharge port 32 where discharge passages 30 and 31 are joined.
(Not shown in FIG. 1).

Further, a passage 7 is formed in the pump body 1 for communicating the suction chamber 3 of the pump unit B with the discharge passage 30 of the pump unit A. A normally-closed valve 33 and an orifice 35, which open the passage 7 by energization, are formed in the middle thereof. Are interposed in series.

The opening and closing of the valve 33 is controlled via a controller of another unit that energizes the valve 33 based on the magnitude of the required pump discharge flow rate, for example, based on detection values of various sensors.

 Next, the operation will be described.

When the motor is connected to the rotating shaft 4 and driven to rotate, in the pump unit A, the rotation of the eccentric cam 8 causes the piston 10 to repeatedly enter the oil chamber 9 and project to the suction chamber 2. And
When projecting from the oil chamber 9 to the suction chamber 2, the working oil in the suction chamber 2 is sucked from the suction port 12 and pressurized by entering the oil chamber 9, and discharged to the discharge passage 30 through the check valve 15. I do. In this way, the hydraulic oil is discharged from the plurality of oil chambers 9 into the discharge passage 30 with a constant phase difference. As shown in FIG. 3, the discharge flow rate of the discharge passage 30 increases in proportion to the rotational speed of the eccentric cam 8 to some extent, but thereafter the suction resistance by the orifice 14 increases with the rotational speed. It is almost constant irrespective of it.

Also, in the pump unit B, when the valve 33 is closed, similarly to the pump unit A, the piston 20 driven by the rotary cam 18 sucks the operating oil in the suction chamber 3 into the oil chamber 18 and pressurizes the same. By discharging to 31, the same flow characteristics are exhibited. Therefore, when the valve 33 is closed, the total flow rate of the pump units A and B is discharged to the discharge port 32.

On the other hand, when the valve 33 is opened by energization from the controller, the high-pressure hydraulic oil discharged into the discharge passage 30 of the pump unit A is guided to the suction chamber 3 of the pump unit B via the passage 7. As a result, the suction chamber 3 becomes high pressure, and the piston
Due to the action of this high pressure, 20 stays in the oil chamber 19 against the spring 21 and separates from the eccentric cam 18. For this reason, the eccentric cam 18 only idles in the suction chamber 3, does not drive the piston 20, and stops the discharge of the hydraulic oil from the oil chamber 19 to the discharge passage 31. Therefore, only the flow rate of the pump unit A shown in FIG. 3 is supplied from the discharge port 32.
In this state, since the eccentric cam 18 of the pump unit B is idling, the load is extremely small, and the rotating shaft 4
The load on the motor that drives the motor is also reduced. Note that a large amount of high-pressure hydraulic oil in the suction chamber 3 does not flow out of the suction passage 23 due to the flow resistance of the orifice 24 interposed between the suction chamber 3 and the suction passage 23.

When the controller closes the valve 33, the pressure in the suction chamber 3 becomes low again, and the piston 20 urged by the spring 21 projects into the suction chamber 3 and abuts the bottom portion on the eccentric cam 18, so that the driving of the piston 20 is restarted. Then, the pump unit B starts discharging the hydraulic oil again. In this way, the pump discharge amount is quickly switched between the large and small stages through the opening and closing of the valve 33, so that the necessary flow rate is always supplied from the pump. In addition, the power consumption of the motor that drives the rotation shaft 4 is small.

(Effects of the Invention) As described above, the present invention configures two radial piston pump units on a single rotating shaft and guides the discharge oil of one pump unit to the suction chamber of the other pump unit. A passage and a valve for opening and closing the passage are provided, so that when the valve is closed, the two pump units respectively discharge hydraulic oil, and when the valve is opened, the other pump is put into the suction chamber of one pump unit. The discharge oil of the pump unit is guided, and the piston facing the suction chamber is separated from the eccentric cam by the forced displacement in the evacuation direction due to the action of the high pressure and remains in the oil chamber. The discharge is stopped, and only one of the pump units continues to discharge the hydraulic oil. Accordingly, the pump discharge flow rate can be quickly switched by controlling the opening and closing of the valve, and when the flow rate is small, the load can be reduced to save the driving energy of the rotating shaft, and a great energy saving effect can be obtained.

[Brief description of the drawings]

1 is a sectional view of a radial piston pump showing an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram, and FIG. 3 is a graph showing flow characteristics. FIG. 4 is a hydraulic circuit diagram for explaining a general hydraulic cylinder driving mechanism. 1 ... Pump body, 2,3 ... Suction chamber, 4 ... Rotary shaft,
7 ... passage, 8,18 ... eccentric cam, 9,19 ... oil chamber, 10,20
…… Piston, 30, 31 …… Discharge passage, 33 …… Valve, A, B
……Pumping unit.

Claims (1)

(57) [Scope of request for utility model registration] An eccentric cam fixed to a rotary shaft, a suction chamber for accommodating the eccentric cam, an oil chamber formed radially with respect to the rotary shaft, and an oil chamber driven by the eccentric cam. The two pump units, which reciprocate the piston and reciprocate the piston and discharge the hydraulic oil sucked into the oil chamber from the suction chamber to the discharge passage on the same rotary shaft, and one of the pump units A passage communicating the discharge passage of the other pump unit with the suction chamber of the other pump unit, and a valve for opening and closing the passage, and the discharge pressure introduced into the suction chamber of the other pump unit with the opening of the valve. A radial piston pump, wherein the piston of the pump unit is separated from the eccentric piston.