GB2169966A - Rotary vane pump - Google Patents

Abstract

The pump is provided with pivoted vanes 3 which swing into recesses 5 in the rotor. Each vane and/or each recess has ribs 8 which, when the vane is fully retraced into recess, form channels 9 which are intended to minimise adhesion between the vane and the rotor when the gap between the surfaces is filled with oil. The ribs may be parallel (Fig. 2) or criss-cross (Fig. 3). <IMAGE>

Description

SPECIFICATION Rotary vane pump The invention relates to a rotary vane pump of the kind with a rotor mounted eccentrically in the cylinder and with pivoted vanes accomodated in axially extending recesses in the rotor, the vanes being thrust against the cylinder wall by centrifugal force or by springs.

Pumps of this kind (compare the German Offenlegungsschrift DE-OS 30 14 520) are suitable for use as vacuum pumps for producing suction, for example for the power assisted brakes, the air conditioners and the like of motor vehicles.

The pump is conventionally driven directly by the engine of the vehicle. The pump sucks air out of the device which is being evacuated and discharges it into the engine crankcase.

When the engine is stopped it often happens that residual suction in the evacuated device sucks oil from the engine, or from the lubrication system, back into the pump.

The oil forms a film between the pivoted vane and the rotor, when the vane is in its fully retracted position, filling the residual gap between these parts, with the result that they adhere together, so that when the pump is subsequently started it is inoperative, i.e. it does not pump. This is particularly disadvantageous when the device to be evacuated is a power assisted brake, which consequently fails to respond, for lack of suction, when braking action is next required.

The intention in the invention is to obviate this disadvantage in rotary vane pumps. The problem is solved by the characteristics claims in Claim 1.

Further developments of the invention are described in the subsidiary claims.

Therefore, this invention provides a rotary vane pump with a rotor mounted eccentrically in the cylinder and with pivoted vanes accomodated in axially extendeing recesses in the rotor, the vanes being thrust against the cylinder wall by centrifugal force or by springs, and in which several channels are formed between the vane and the rotor when each pivoted vane is fully retracted.

The arrangement of the pump provided according to the invention prevents the pivoted vanes from sticking to the rotor and makes it possible to reduce still further the width of the gap remaining between these two parts when the vane is in its fully retracted position. Consequently dead space can be reduced. The new pump works more effectively, producing a higher degree of suction, and starts pumping as soon as the engine is started.

Two examples of the invention will now be described with the help of the drawing, in which: Figure 1 is a cross section of the pump, with the front cover removed.

Figures 2 and 3 show two examples of the ribbed surfaces.

Figure 1 shows a known rotary vane pump, with a pump cylinder 1 containing, mounted eccentrically, a rotor 2 equipped with three vanes 3, each of which is pivoted to the rotor 2 by a pivot foot 4 which is essentially circular cylindrical in shape and works in a corresponding axially extending recess in the rotor 2. Each pivoted vane 3 is thrust against the inner surface of the cylinder 1 by a spring, which is not shown in the drawing. When the pump is in operation each vane 3 oscillates, by a pivoting movement, about the central axis of its pivot foot 4. In this oscillating movement the vane 3, whose arm 6 has a terminal curvature 10, swings inwards until it fits snugly in a recess 5 of the rotor 2, as shown at the right in Figure 1. This occurs at the location where there is the least distance between the rotor 2 and the cylinder 1.Under these circumstances there is only a very small remaining gap between the rotor 2 and the inner surface of the vane 3, the curvature of the recess 5 agreeing closely with the whole of the curvature of the inner surface of the vane 3.

As the method of functioning of rotary vane pumps of this kind is generally known, it need not be described here.

The inner surface of the vane 3 has ribs 8, as shown at 7 in Figure 1, and/or the corresponding surface of the recess 5 in the rotor 2 has ribs.

When the vane 3 is fully retracted into the recess 5 the ribs 8 form channels 9 which can terminate, for example, at the axiai end-faces of the rotor 2, or at the terminal curvature 10 of the arm 6 of the vane 3.

Figures 2 and 3 show examples of the ribs 8.

Figure 2 shows parallel ribs 8, whereas in Figure 3 the ribs run criss-cross over the surface.

The ribs reduce the contact area between the parts 2 and 3, minimising the adhesion between them.

1. A rotary vane pump with a rotor mounted eccentrically in the cylinder and with pivoted vanes accomodated in axially extending recesses in the rotor, the vanes being thrust against the cylinder wall by centrifugal force or by springs, characterised in that when each pivoted vane is fully retracted, several channels (9) are formed between the vane (3) and the rotor (2).

2. A rotary vane pump as claimed in Claim 1, characterised in that the channels (9) are formed by ribs (8).

3. A rotary vane pump as claimed in Claim 2, characterised in that the ribs run criss-cross.

4. A rotary vane pump as claimed in Claims 2 or 3, characterised in that the ribs (8) are on the inner surface (7) of the vane (3).

5. A rotary vane pump as claimed in claims 2, 3 or 4, characterised in that the ribs (8) are in the rotor recess (5) which accommodates the arm (6) of the vane (3) when the vane retracts towards the rotor (2).

6. A rotary vane pump substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Rotary vane pump The invention relates to a rotary vane pump of the kind with a rotor mounted eccentrically in the cylinder and with pivoted vanes accomodated in axially extending recesses in the rotor, the vanes being thrust against the cylinder wall by centrifugal force or by springs. Pumps of this kind (compare the German Offenlegungsschrift DE-OS 30 14 520) are suitable for use as vacuum pumps for producing suction, for example for the power assisted brakes, the air conditioners and the like of motor vehicles. The pump is conventionally driven directly by the engine of the vehicle. The pump sucks air out of the device which is being evacuated and discharges it into the engine crankcase. When the engine is stopped it often happens that residual suction in the evacuated device sucks oil from the engine, or from the lubrication system, back into the pump. The oil forms a film between the pivoted vane and the rotor, when the vane is in its fully retracted position, filling the residual gap between these parts, with the result that they adhere together, so that when the pump is subsequently started it is inoperative, i.e. it does not pump. This is particularly disadvantageous when the device to be evacuated is a power assisted brake, which consequently fails to respond, for lack of suction, when braking action is next required. The intention in the invention is to obviate this disadvantage in rotary vane pumps. The problem is solved by the characteristics claims in Claim 1. Further developments of the invention are described in the subsidiary claims. Therefore, this invention provides a rotary vane pump with a rotor mounted eccentrically in the cylinder and with pivoted vanes accomodated in axially extendeing recesses in the rotor, the vanes being thrust against the cylinder wall by centrifugal force or by springs, and in which several channels are formed between the vane and the rotor when each pivoted vane is fully retracted. The arrangement of the pump provided according to the invention prevents the pivoted vanes from sticking to the rotor and makes it possible to reduce still further the width of the gap remaining between these two parts when the vane is in its fully retracted position. Consequently dead space can be reduced. The new pump works more effectively, producing a higher degree of suction, and starts pumping as soon as the engine is started. Two examples of the invention will now be described with the help of the drawing, in which: Figure 1 is a cross section of the pump, with the front cover removed. Figures 2 and 3 show two examples of the ribbed surfaces. Figure 1 shows a known rotary vane pump, with a pump cylinder 1 containing, mounted eccentrically, a rotor 2 equipped with three vanes 3, each of which is pivoted to the rotor 2 by a pivot foot 4 which is essentially circular cylindrical in shape and works in a corresponding axially extending recess in the rotor 2. Each pivoted vane 3 is thrust against the inner surface of the cylinder 1 by a spring, which is not shown in the drawing. When the pump is in operation each vane 3 oscillates, by a pivoting movement, about the central axis of its pivot foot 4. In this oscillating movement the vane 3, whose arm 6 has a terminal curvature 10, swings inwards until it fits snugly in a recess 5 of the rotor 2, as shown at the right in Figure 1. This occurs at the location where there is the least distance between the rotor 2 and the cylinder 1.Under these circumstances there is only a very small remaining gap between the rotor 2 and the inner surface of the vane 3, the curvature of the recess 5 agreeing closely with the whole of the curvature of the inner surface of the vane 3. As the method of functioning of rotary vane pumps of this kind is generally known, it need not be described here. The inner surface of the vane 3 has ribs 8, as shown at 7 in Figure 1, and/or the corresponding surface of the recess 5 in the rotor 2 has ribs. When the vane 3 is fully retracted into the recess 5 the ribs 8 form channels 9 which can terminate, for example, at the axiai end-faces of the rotor 2, or at the terminal curvature 10 of the arm 6 of the vane 3. Figures 2 and 3 show examples of the ribs 8. Figure 2 shows parallel ribs 8, whereas in Figure 3 the ribs run criss-cross over the surface. The ribs reduce the contact area between the parts 2 and 3, minimising the adhesion between them. CLAIMS

1. A rotary vane pump with a rotor mounted eccentrically in the cylinder and with pivoted vanes accomodated in axially extending recesses in the rotor, the vanes being thrust against the cylinder wall by centrifugal force or by springs, characterised in that when each pivoted vane is fully retracted, several channels (9) are formed between the vane (3) and the rotor (2).

2. A rotary vane pump as claimed in Claim 1, characterised in that the channels (9) are formed by ribs (8).

3. A rotary vane pump as claimed in Claim 2, characterised in that the ribs run criss-cross.

4. A rotary vane pump as claimed in Claims 2 or 3, characterised in that the ribs (8) are on the inner surface (7) of the vane (3).

5. A rotary vane pump as claimed in claims 2, 3 or 4, characterised in that the ribs (8) are in the rotor recess (5) which accommodates the arm (6) of the vane (3) when the vane retracts towards the rotor (2).

6. A rotary vane pump substantially as hereinbefore described with reference to the accompanying drawings.