JPS61241503A - Hydraulic driving system - Google Patents

Abstract

PURPOSE:To move a cylinder at high speed with a small-flow hydraulic pump by connecting the supply side of a cylinder to an accumulator and a hydraulic pump through a valve, and simultaneously connecting same to the lower pressure side through a valve. CONSTITUTION:The supply side of a cylinder 6 is connected to the discharge side of a hydraulic pump 1 through a valve 9 and an accumulator 3, and simultaneously connected to the low pressure side which is the suction side of the hydraulic pump 1 through a valve 10. In this arrangement, when the hydraulic pump 1 is driven to store a fixed amount of high pressure oil in an accumulator 3, the cylinder 6 can be moved at arbitrary speed by opening and closing the valves 9, 10.

Description

[Detailed Description of the Invention] "Technical Field of Application" This invention relates to a hydraulic drive system using an electromagnetic pump, and in particular, "prior art and problems" related to a hydraulic drive system that can obtain fast response with an electromagnetic pump with a small discharge flow rate. It is possible to set the discharge pressure of hydraulic pumps such as electromagnetic pumps to a fairly high value, but if you try to increase the flow rate, the structure of the pump will become thicker (and the power consumption will also increase, and the cost will increase). On the other hand, if the cylinder is driven with a reduced discharge flow rate, there is a drawback that the response becomes poor.

[Objective] The present invention aims to eliminate such conventional drawbacks, and aims to obtain a hydraulic drive system that has low flow rate and high speed.

Embodiment In FIG. 1, a hydraulic pump 1 is constituted by, for example, a solenoid valve, and its discharge side is connected to the high pressure side of an accumulator 3 via a check valve 2.

This accumulator has a piston 5 biased by a spring 4, but its structure is limited to that shown in the figure (although various types can be used). It has a piston 8 biased in one direction by a spring 7, and its high pressure side is connected to the high pressure side of the accumulator 3 via a valve 9.The high pressure side of the cylinder 6 is connected via a valve 10 to the high pressure side of the accumulator 3. The hydraulic pump 1 is connected to the low pressure side, and this low pressure side is connected to the hydraulic pump 1.
connected to the suction side of the Further, an oil tank 12 is connected to the suction side of the hydraulic pump 1 via a check valve 11. It is also possible to use a three-way valve 13 as shown in FIG. 2, for example, as the valves 9 and 10.

"Operation" In the above configuration, when the hydraulic pump 1 is operated with the valves 9 and 10 shown in FIG. It moves to the low pressure side, and the inside of the accumulator 3 reaches a predetermined high pressure. When moving the cylinder 6, the valve 9 is opened while the valve 1° is closed. Then, the high-pressure oil in the accumulator 3 flows at high speed into the suction side of the cylinder 6, that is, the high-pressure side, due to the biasing force of the spring 4, so the piston 8 moves at high speed toward the low-pressure side against the biasing force of the spring 7. do. When the valve 9 is closed in this state, oil flows into the accumulator 3 again and its pressure increases. At this time, since both valves 9 and 10 are closed, a high pressure is maintained on the suction side of the cylinder 6, and therefore the cylinder 6 remains moved to the right in FIG. Next, in order to return the piston 8 of the cylinder 6 to its original position, the valve 10 may be opened for a predetermined period of time. That is, the biasing force of the spring 7 causes the piston 8 to move to the left in the figure.

Note that when the cylinder 6 is temporarily required to have high-speed response, but is not required to have continuous high-speed response at other times, such as in a normal hydraulic drive system,
Hydraulic pump 1 for non-continuous and frequent applications
This means that high speed performance can be achieved even if the flow rate is large.

For example, if the volume of the accumulator 3 is N times the required volume of the cylinder 6, the cylinder 6 can be made to respond quickly at least N times.

In addition, by keeping the pressures on the low pressure side of the accumulator 3 and cylinder 6 the same and approximately atmospheric pressure pA,
Fluctuations in the volume of the oil tank 12 due to movement of oil can be made extremely small. From now on, fluctuations in the volume of the oil tank 12 can be absorbed by simply covering the expansion of oil temperature due to temperature changes, and can therefore be handled with an extremely simple structure such as a diaphragm.

In addition, in the system shown in FIG. 2, in order to accumulate pressure in the accumulator 3, the three-way valve 13 is switched to select route b, and when the cylinder 6 is operated, the three-way valve 13 is switched.
3 to route a.

"Effects" As described above, this invention connects the low pressure side of the cylinder 6) to the low pressure side of the accumulator 3 and the suction side of the hydraulic pump 1, and further connects the supply side of the cylinder 6 and its low pressure side via the valve 10. Since the discharge side of the hydraulic pump 1 is connected to the supply side of the cylinder 6 via the accumulator 3 and the valve 9, the high speed of the cylinder 6 can be achieved even if the hydraulic pump has a small flow rate. Moreover, since the oil is circulated and used, it is always kept clean and there is almost no need for replenishment, which has the advantage of easy maintenance and simple construction.

[Brief explanation of the drawing]

FIG. 1 is a fluid circuit diagram showing one embodiment of a hydraulic drive system according to the invention, and FIG. 2 is a fluid circuit diagram showing another embodiment of the invention. 1... Hydraulic pump, 2... Check valve, 3... Accumulator, 4... Spring, 5... Piston,
6...Cylinder, 7...Spring, 8...Piston, 9...Valve, 10...Valve, 11...Check valve, 12...Oil tank. 13...Three-way valve. Patent applicant Yamatake Newell Co., Ltd. Agent
Patent Attorney 1) Hiroshi Sawa (2 others)

Claims (1)

[Claims] The discharge side of the hydraulic pump is connected to the supply side of the cylinder via an accumulator and a valve, and the low pressure side of the cylinder is connected to the low pressure side of the accumulator and the suction side of the hydraulic pump, and the supply side of the cylinder is connected to the supply side of the cylinder. A hydraulic drive system that connects the side and its low pressure side via a valve.