JPS6026189A - Pressure balance valve for piston vacuum pump - Google Patents

Abstract

PURPOSE:To simplify the structure considerably while to increase the effective valve function of a pressure balance valve, by performing opening/closing of pressure balance valve and sliding of a pressure balancing sleeve through the piston itself. CONSTITUTION:At the final stage where a piston 3 will move in the arrow X direction in a cylinder 2 of the first stage pump 1, a stopper chip 15 provided on the head of the piston 3 will contact against a pressure balance first sleeve 10 and a ball valve 13 to open the valve port 12 thus to close a suction valve 6 and to block the gas compressed by the piston 3 from returning to the suction chamber 8. Simultaneously with opening of the valve port 12, pressure in the delivery chamber 9 will enter into the cylinder 2 to bring the pressure delivery chamber 9 near to balance. Consequently, the pressure of gas in the cylinder 2 will increase sufficiently to open the delivery valve 7 and to compress the gas into the delivery chamber 9, resulting in considerable simplification of the structure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure balancing valve for a piston vacuum pump.

A rotary vacuum pump such as a vane type does not have reciprocating motion like a piston type vacuum pump, so it does not have a suction valve or a discharge valve.Compare the pump mechanisms that compress the diluted gas that is vacuum-suctioned and discharge it to the discharge side. It can be configured as a 1lili product, but like the piston type, oil sealing oil is supplied from the suction side.
In order to improve the vacuum suction function and prevent burning, an oil mist recovery device or an oil spill prevention valve is installed on the discharge side to prevent oil mist from getting mixed into the compressed 1n discharge gas on the discharge side. However, there is no way to completely prevent oil mist from entering the compressed exhaust gas, and not only is the oil-contaminated υF gas discharged into the atmosphere from the exhaust chimney, but this also reduces the consumption of oil seal oil. In addition, high-vacuum models often require a force that exceeds 50% of the piston reciprocation driving power of a piston-type vacuum pump.

On the other hand, the ζ screw type vacuum pump requires less driving power for the piston, and can effectively reduce the rate of seal oil mixing into the compressed exhaust gas and the consumption of oil seal oil. ζThe flit thin gas sucked into the cylinder must be compressed to a pressure that overcomes the pressure on the exhaust side (usually external pressure, and in the case of the first stage pump of a two-stage vacuum pump, it is below the external pressure) during the entire gas compression stroke. Since the discharge valve cannot be opened, it is necessary to install a pressure balance valve that introduces the discharge side pressure into the cylinder at the end of the compression stroke.

For example, the balance valve is a sliding valve in which an eccentric cam is interlocked by a crank mechanism that drives a piston rond, and a sliding valve is driven by the mechanism of the eccentric cam to open and close a valve port for introducing the discharge side pressure into the cylinder when necessary. The pressure balancing valve, which is a slide valve, and the crank mechanism that is the drive mechanism for the valve are large-scale. Reduces the use of vacuum pumps.

The present invention aims to improve the above-mentioned drawbacks by arranging the above-mentioned pressure balance valve to be opened and closed by the reciprocating piston itself. A balancing sleeve is installed, and a pressure balancing valve is provided that protrudes into the cylinder to close the valve port provided in the balancing sleeve by force, and the head of the piston is provided with a pressure balancing valve that protrudes into the cylinder. It is characterized by the provision of a contact portion that pushes the valve and pressure balancing sleeve to avoid movement.

Embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows a two-stage piston type vacuum pump, in which the first stage pump (1) and the second stage pump (I [) are pumped into a cylinder 2.22 attached to the end plate 1, alternately performing suction strokes and compression strokes. A biston rod 3.23 that performs reciprocating motion is fitted, and each is connected to a piston rod 4.24 driven by a crank mechanism.
Ru.

The end plate 1 has a suction valve 6 and a discharge valve 7 corresponding to the first stage pump (1) and a suction valve 26 corresponding to the second stage pump (If).
A cover 5 is provided with a discharge valve 27, and a suction chamber 8 is connected to a suction pipe 8a, a discharge chamber 9 is connected to a discharge pipe 9a, and a suction chamber 28 is connected to a suction pipe 28a. , a discharge chamber 29 connected to a discharge pipe 29a,
They are provided corresponding to each of the suction valves 6.26 and the discharge valves 7.27, respectively. The suction pipe 8a is connected to a vacuum chamber etc., the discharge pipe 9a is connected to the suction pipe 28a, and the discharge pipe 29
A is connected to an exhaust pipe or the like. In this embodiment, in the above-mentioned known structure, a first sleeve 1o for pressure balancing, which has both ends facing the discharge chamber 9 and the inside of the cylinder 2 and is passed freely through the end plate 1 for IM movement, and a first sleeve 1o with both ends facing the discharge chamber 29 A second pressure balancing sleeve 30 is provided which faces the inside of the cylinder 22 and freely slides through the end plate 1. Each sleeve 1o, 30
is designed to prevent pressure leakage from the insertion portion into the end plate 1, and is provided with engagement flanges 11.31 on the discharge chamber 9 and discharge chamber 19 sides, and a valve port on the cylinder 2.22 side. 1
2.Open each 32.

13.33 is inserted into the first pressure balancing sleeve 10 and the second sleeve 30 from the discharge chamber 9.29 side, and the respective valve ports 1
It is a ball valve that is in pressure contact with the cylinder 2.32 and has a portion of each protruded into the cylinder 2.22. 34 is loosely inserted into the first sleeve 10 and the second sleeve 30, and a ball valve 13.3 which is an example of a pressure balancing valve is formed.
3, the elastic action of these springs causes the ball valve 14.
33 are pressed against the valve ports 12.32, respectively, and at the same time, the first sleeve 10 and the second sleeve 30 are projected into the syringe 2.22 due to their elasticity.

The ball valve 13 and the first sleeve 10 for pressure equalization are sequentially attached to the spatula l' of the piston 3, and the ball valve 33 and the second sleeve for pressure equalization are attached to the hem of the piston 23. Abutment piece 3 that hits 30 and 30 in sequence
Install 5.

FIGS. 3 and 4 show several examples of the shape of the contact piece 15, 35 for the first pressure-balancing sleeve lO or the second pressure-balancing sleeve 30. Make a cut a or b from the periphery.

FIG. 5 shows an embodiment in which the first sleeve 10 or the second sleeve 30 and the ball valve 13, 33 are provided with separate springs C1d.

Figure 6 shows lIIJlg instead of ball valve 13.33.
An embodiment using a flat sheet-shaped valve f protruding from the Ji port is shown.

To explain the operation of the embodiment shown in Fig. 1.2, for example, in the m1 stage bopon (I), at the end of moving the piston 3 in the ζ cylinder 2 in the direction of the arrow X in Fig. I5
opens the ζ valve port 12 corresponding to the ball valve 13, at which time the suction valve 6 is closed and the compressed gas compressed by the piston 3 is not returned to the suction chamber 8. At the same time as the valve port 12 is opened, the pressure in the discharge chamber 9 enters the cylinder 2, bringing the pressure in the discharge chamber 9 close to equilibrium. Therefore, the gas compression within the syringe 2 is sufficiently increased, and the discharge force 7 is opened to force out the ζ compressed gas into the discharge chamber 9. Piston 3 is ′ζ relative to top dead center
When entering the suction stroke of movement in the direction of the y arrow in FIG. 2, the discharge valve 7 is closed, but the pressure balancing first sleeve 1
Until the engagement collar 11 of 0 engages with the end plate 1, the ball valve 13
Since ζ remains pressed by the piece 15 against the first spring 14, the pressure difference between the inside and outside of the suction valve 6 is such that the cylinder 2 side prevails, and ζ will open the valve 6 in most cases. do not have. When the engaging collar 11 engages with the end plate 1 and the C piece 15 separates from the ball valve 13, the inner space of the cylinder 2 becomes vast and the pressure in the suction chamber 8 overcomes the pressure in the cylinder 2. . For this reason, the suction valve 6 is opened to introduce a low pressure gas pressure body into the cylinder 2. When the piston 3 begins to move in the direction of the arrow X in FIG. 1, the suction valve 6 is closed by the pressure within the cylinder 2, and thereafter the same operations as described above are performed.

The operation of the second stage pump (It) is also basically the same as that of the first stage pump (I), so a description thereof will be omitted.

As is clear from the foregoing description, the present invention provides a pressure equalization sleeve that is slidably protruded into the cylinder of a piston-type vacuum pump from a discharge chamber side that is blocked off through a discharge valve, and a valve for the sleeve. A pressure equalization valve whose opening is closed by biasing pressure and whose closed part protrudes partially into the silling is provided, and an abutment piece that abuts the pressure flat during the compression stroke of the piston. The impact of the piece against the pressure equalization valve opens said valve port, and then the pressure of the discharge chamber is introduced into the cylinder by pushing the equalization sleeve, so that the pressure in the syringe is balanced with the pressure in the discharge chamber, and the cylinder is closed. The pressure balancing valve device increases the density of the gas body and obtains sufficient compression pressure in the compression stroke of the piston to overcome the pressure in the suction chamber and open the discharge force. The sliding of the sleeve is actuated by the piston itself, and the pressure in the discharge chamber and the pressure in the cylinder are adjusted by adjusting the degree of protrusion of the sleeve pushed together with the pressure balancing valve into the syringe. The timing at which the internal pressure reaches equilibrium can be freely changed, making the valve action of the pressure balancing valve advantageous.
It has the advantage that the entire structure can be extremely simplified compared to a conventional piston type vacuum pump with a pressure balance valve.

[Brief explanation of drawings]

Figure 1.2 is a vertical sectional side view showing an embodiment of the present invention;
5 and 4 are perspective views illustrating the corresponding parts of the pressure balancing sleeve and the C piece, and FIGS. 5 and 6 are longitudinal sectional side views of a portion of other embodiments. 2.22 → cylinder 3.23 → screw in 6.26 → suction valve 7.27 → discharge valve 9.29 - discharge chamber 12.32 → valve port 13.33 → ball valve 15.35 → this - C piece 30→Second sleeve for pressure balance Applicant Annshi Co., Ltd. Figure 3 1'J35)

Claims (1)

[Claims] In a piston type vacuum pump, the suction valve is opened during the suction stroke of the piston to create a vacuum suction into the cylinder, and in the compression stroke, the discharge valve is opened to discharge the compressed gas in the cylinder. A sleeve for the pressure plate 1 (φi) that protrudes freely into and out of the cylinder is installed, and a sleeve for the pressure plate (φi) is installed, and the valve port communicating with the cylinder is closed to partially seal the cylinder. Pressure balance of a piston-type vacuum pump, characterized in that a pressure equalizer protrudes inward, and the head of the piston is provided with a contact portion that moves by pushing a pressure equalizer and a pressure equalizer sleeve during a compression stroke. valve.