JPS61215484A - Rotary vane type vacuum pump - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the seizure of a pump and deterioration in efficiency, by a method wherein a space between the rotor of a vane type vacuum pump and a bearing is communicated with the open air through communicating holes, and check valves, adapted to prevent entrance of refuse from the open air, are located in the communicating holes. CONSTITUTION:Communicating holes 13a and 13b are formed between spaces 12a and 12b, formed between a rotor 3 of a vane type vacuum pump and each of bearings 5a and 5b, and the open air, and check valves 14a and 14b, adapted to prevent the flow of fluid from the open air to the interior of the pump, are located in the communicating holes 13a and 13b, respectively. As a result, when the interior of the pump is brought into a positive pressure, wear powder of the vane is discharged through the communicating passage 13a and 13b, and when the interior of the pump is brought into a negative pressure, the communicating passages 13a and 13b are closed by the check valves, and this results in prevention of refuse from the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a rotary vane vacuum pump, and more particularly to the structure of a vane abrasion powder discharge hole of an oil-free rotary vane vacuum pump that is operated intermittently.

[Background of the invention]

The structure of the vane abrasion powder discharge hole of a conventional rotary vane pump is to simply provide a through hole as described in JP-A-54-112603, or to allow gas to flow from the rotor side to the atmosphere side through the through hole. It was designed with a check valve to prevent this. However, with this structure, when used as a vacuum pump in a dusty place, the rotor may be damaged due to dust being sucked into the rotor.
No consideration was given to abnormal wear of the vanes.

[Purpose of the invention]

An object of the present invention is to provide a structure that can prevent backflow of air and inflow of dust from the atmosphere into the pump through wear debris discharge holes used in oil-free rotary vane vacuum pumps that are operated intermittently.

[Summary of the invention]

A feature of the present invention is that a check valve that prevents air from flowing into the pump from the atmosphere is provided in a part of the wear dust discharge hole to prevent dust from flowing into the cylinder when the inside of the pump becomes vacuum. At the same time, vane abrasion powder is discharged by air flow from the inside of the pump toward the atmosphere, which is generated when the inside of the pump becomes positive pressure when the pump is started.

[Embodiments of the invention]

An embodiment of the present invention will be explained below with reference to FIG. 1. A hollow cylindrical center case closed at both ends with side plates la and lb. A rotor 3 is provided inside. The rotor 3 is rotatably supported via a rotor shaft 4 formed integrally with the rotor 3 by bearings 5a and 5b provided on both sides of the rotor.

A vane 7 is held in a groove 6 provided in the rotor 3 so as to be slidable in the radial direction. The vanes 7 come into contact with the inner surface of the center case 2 due to centrifugal force when the rotor 3 rotates.

An intake hole 8 is provided at an appropriate position on the center case 2. An exhaust hole 9 is provided. The inner surface shape of center case 2 is as follows. Vane 7, rotor 3. Side plate la, 1
The volume of the space formed by b is determined to be large near the intake hole and small near the exhaust hole. Therefore rotor 3
When it rotates.

The gas sucked through the intake hole 8 is compressed and flows out from the exhaust hole 9.

The rotor 3 is held by a leaf spring 10 and an adjustment screw 11 so as not to come into contact with both side plates la, lb.

Between the side plates la, lb and the bearings 5a, 5b,
Rotor shaft 4. The rotor 3. is inserted through the gap between the side plates la and lb. A void 12a that connects to the void between the side plates la, lb.

12b is provided. Hollow spaces 12a and 12b are adjustment screws 1
Bearings 5a, 5 when adjusting the position of the rotor 3 using 1
Also serves as the remaining portion of b. There is a through hole 13 in the empty space that communicates with the atmosphere.
One end of a and 13b is open.

There is a space 12a from the atmosphere in the middle of the through holes 13a and 13b.

A check valve 14a prevents backflow of air to 12b.

14b is provided.

In the oil-free rotary vane vacuum pump to which the present invention is applied, when the rotor 3 rotates, the vanes 7 come into contact with the inner surface of the center case 2 and slide. Since the vanes 7 are generally made of carbon material to prevent seizure, a large amount of abrasion powder is generated.

At this time, the pressure inside the pump is lower than the atmospheric pressure, so the check valves 14a and 14b are closed, and part of the generated wear powder flows out together with air from the exhaust hole 9, and part of it flows out from the rotor 3.
Passing between side plates la and lb, space Lea, 12b
accumulate inside. When the amount of accumulated wear powder increases, the inside of the vane groove 6 and the rotor 3. It accumulates between side plates la and ib.

In addition to impairing the movement of the vane 7 and the movement of the rotor 3,
Since it enters the bearings 5a and 5b and accelerates the wear of the bearings, it is necessary to quickly drain it out of the pump.

Since the vacuum pump to which the present invention is applied is used in intermittent operation, there are times when the rotor 3 stops and the inside of the pump becomes atmospheric pressure. When the rotor 3'' starts rotating again from the second condition, the pressure around the rotor shaft 4 becomes higher than atmospheric pressure until the pressure in the intake hole 8 is sufficiently reduced, and the check valves 14a and 14b open and vacuum operation is started. The wear powder of the vanes accumulated in the cavities 12a and 12b is carried by the air flow and discharged to the atmosphere.Furthermore, when the pressure in the intake hole 8 is sufficiently lowered, the pressure around the rerotor shaft 4 drops below atmospheric pressure. Then, the check valves 14a and 14b close to prevent dust from the atmosphere from flowing into the pump.

The structure of the check valve 14a is shown in FIG. 3. A portion of the communication passage 13a expands to form a valve chamber 15, and a conical seat surface 16 is formed above the valve chamber 15.

A protrusion 17 is formed at the bottom of the valve chamber 15, and a seat surface 16
A spherical valve body 18 is installed between the protrusion 17 and the protrusion 17 . The center of the seat surface 16 is connected to the cavity 12a through a communication path 12a, and the lower end of the valve chamber 15 is connected to the atmosphere through a communication path 13a. Therefore, the check valve 14a opens when the cavity 12a becomes a positive pressure to discharge wear particles, and closes when the cavity 12a becomes a negative pressure to prevent dust from entering. Also, when the pump is stopped, the valve body 18 is
, and the check valve 14a is opened. however.

At this time, if vibration is applied to the pump body, the valve body 18 will move into the valve chamber 15.
The protrusion 17 moves around inside the seat surface 16 to knock off abrasion particles adhering to the seat surface 16, and the protrusion 17 prevents the valve body 18 from falling into the lower end, so that the valve body 18 is immediately moved when the space 12a becomes negative pressure. The stroke of the valve body 18 is adjusted so that the valve body 18 hits the seat surface 16 with light vibration while ensuring the operation of coming into close contact with the seat surface 16. Therefore, this check valve 14
A is most effective when installed in a vehicle, etc., where vibrations are applied even when the pump is stopped.

Considering that the valve body 18 moves in wear particles and can rapidly prevent backflow, it has excellent wear resistance in dry conditions.
A ball made of plastic such as Teflon, which has a low specific gravity, is preferable, and the check valve 14b side has the same structure.

Therefore, there is an effect that the degree of vacuum is improved compared to the case where a communication hole for discharging wear powder is simply provided.

Furthermore, the filter will not be clogged with abrasion particles that would otherwise occur when a filter is used to prevent inhalation of dust.

〔Effect of the invention〕

Therefore, according to the present invention, vane abrasion powder generated from an oil-free rotary vane vacuum pump that is operated intermittently can be quickly discharged, and dust in the atmosphere can be prevented from entering the pump. This has the effect of improving the durability of. This effect is particularly useful when used in dusty areas such as negative pressure sources for on-vehicle vacuum boosters.

Moreover, maintenance-free operation is required, which is particularly important for applications where vacuum is required intermittently.

[Brief explanation of drawings]

FIG. 1 is a central sectional view of an embodiment of the present invention, and FIG. 2 is a central sectional view of an embodiment of the present invention.
1 and 3 are detailed sectional views of the check valve. 1a...Side plate (a), lb...Side plate (b), 2...Center case, 3...Rotor, 4...Rotor shaft, 5&...Bearing, 5b... Bearing, 6...groove.

Claims (2)

[Claims] 1. Center case, a rotor that rotates within the center case and is supported by bearings at both ends, vanes held in grooves provided in the rotor, and side plates that partition both end surfaces of the rotor.As the rotor rotates, the center In a rotary vane vacuum pump that performs pumping action by changing the volume of a space partitioned by a case, rotor, vanes, and side plate, a through hole is provided to communicate the space between the rotor and the bearing with the atmosphere, and the A rotary vane vacuum pump characterized in that a check valve is provided in a part of the hole to prevent flow from the atmosphere side toward the rotor side. 2. The rotary vane vacuum pump according to claim 1, wherein the check valve is configured to open when the vacuum pump is stopped.