GB2169965A - Rotary vane pump - Google Patents

Abstract

The pump is provided with a rotor 3 and with pivoted vanes 5 whose pivot-feet 16 work in recesses in the rotor, each vane being thrust against the cylinder wall by a helical torsion spring 9 whose cylindrical coil 15 is contained and housed in a blind bore 14 in the pivot-foot of the vane, minimising dead space in the pumping cycle. <IMAGE>

Description

SPECIFICATION Rotary vane pump The invention relates to a rotary vane pump of the general kind with a rotor eccentric in the pump cylinder, and with the pivoted vanes whose pivot-feet work in axially extending recesses in the rotor, each vane being thrust against the cylinder wall by a torsion spring whose one end is retained in the rotor, its other end being retained in the vane.

Pumps of this kind are suitable for use as vacuum pumps in motor vehicles, for creating suction for operating brakes, conditioned-air systems and the like.

From the German Offengegungsschrift DE-OS 30 14 520 a pump of this kind is known whose pivoted vanes are thrust against the cylinder wall by hairpin springs.

Due to its short length, a spring of this kind applies a spring force which increases rapidly when the spring is bent and consequently the contact thrust between the pivoted vane and the cylinder wall varies greatly during each revolution of the rotor, resulting in high friction, high power consumption and rapid abrasion.

To remedy this, a pump known from the German Gebrauchsmuster DE 82 34 819 has helical torsion springs with several turns on the coil. The cylindrical coil of each spring is mounted concentrically on a pin projecting from one end of the pivoted vane.

But this arrangement increases the dead space remaining in the pumping chamber when the pivoted vane is in its fully retracted position and, consequently, air under pressure in the pumping chamber escapes backwards, through the dead space, into the suction chamber connected to the device which is being evacuated, reducing the degree of the suction.

The intention in the invention is therefore to improve pumps of this kind by reducing friction between the pivoted vanes and the cylinder wall, with a view to reducing power consumption and abrasion, and to produce a better vacuum in the connected device.

The problem is solved, according to the invention, by the characteristics described in the claim.

Accordingly, this invention provides a rotary vane pump of the general kind with a rotor eccentric in the pump cylinder, and with pivoted vanes whose pivot-feet work in axially extending recesses in the rotor, each vane being thrust against the cylinder wall by a torsion spring whose one end is retained in the rotor, its other end being retained in the vane, and in which the pivot-foot of each vane is essentially, of circular cylindrical cross section, and works in a corresponding axially extending recess in the rotor, a blind bore, which penetrates axially and centrally into the pivot-foot, containing and housing the cylindrical coil of the torsion spring.

An example of the invention is illustrated in the drawing, in which: Figure 1 is a cross section of the pump, with the front cover removed.

Figures 2 and 3 are axial sections of the pivotfoot of one of the vanes.

The rotary vane pump, whose end-wall is known at 1 in Figure 1, has a cylindrical housing 2 in which rotates an eccentric rotor 3 with three pivoted vanes 5 spaced equally around its periphery.

Each vane 5 is pivoted to the rotor 3 by a hollow-cylindrical pivot-foot 16 which works in an axial recess 4 in the rotor 3. Between each two vanes 5 there is formed a pumping chamber 6.

When the pump is in operation gas is aspired through an inlet port 7 from an external device (not shown), which it is desired to evacuate, and expelled through an outlet port 8.

A helical torsion spring 9 thrusts each vane 5 against the inner surface of the cylinder wall, the upper end 10 of the spring 9 being retained in a slot 12 in the rotor 3, its lower end 11 being anchored in a recess 13 situated at the bottom of a cylindrical blind bore 14 which penetrates axially and centrally into the pivot-foot 16, the cylindrical blind bore 14 containing and housing the coil 15 of the helical torsion spring 9.

From the coil 15 the upper end 10 of the spring 9 projects radially outwards through a segmental passage 17 cut through the wall of the hollow pivot-foot 16, the arc of the segmental passage 17 not being great enough to bring the passage 17 into communication, at either end, with a pumping chamber 6 when the vane 5 pivots in the operation of the pump.

1. A rotary vane pump, with a rotor eccentric in the pump cylinder, and with the pivoted vanes whose pivot-feet work in axially extending recesses in the rotor, each vane being thrust against the cylinder wall by a torsion spring whose one end is retained in the rotor, its other end being retained in the vane, characterised in that the pivot-foot (16) of each vane (5) is essentially cylindrical, of circular cross section, and works in a corresponding axially extending recess (4) in the rotor (3), a blind bore (14), which penetrates axially and centrally into the pivot-foot (16), containing and housing the cylindrical coil (15) of the torsion spring (9).

2. 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 (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Rotary vane pump The invention relates to a rotary vane pump of the general kind with a rotor eccentric in the pump cylinder, and with the pivoted vanes whose pivot-feet work in axially extending recesses in the rotor, each vane being thrust against the cylinder wall by a torsion spring whose one end is retained in the rotor, its other end being retained in the vane. Pumps of this kind are suitable for use as vacuum pumps in motor vehicles, for creating suction for operating brakes, conditioned-air systems and the like. From the German Offengegungsschrift DE-OS 30 14 520 a pump of this kind is known whose pivoted vanes are thrust against the cylinder wall by hairpin springs. Due to its short length, a spring of this kind applies a spring force which increases rapidly when the spring is bent and consequently the contact thrust between the pivoted vane and the cylinder wall varies greatly during each revolution of the rotor, resulting in high friction, high power consumption and rapid abrasion. To remedy this, a pump known from the German Gebrauchsmuster DE 82 34 819 has helical torsion springs with several turns on the coil. The cylindrical coil of each spring is mounted concentrically on a pin projecting from one end of the pivoted vane. But this arrangement increases the dead space remaining in the pumping chamber when the pivoted vane is in its fully retracted position and, consequently, air under pressure in the pumping chamber escapes backwards, through the dead space, into the suction chamber connected to the device which is being evacuated, reducing the degree of the suction. The intention in the invention is therefore to improve pumps of this kind by reducing friction between the pivoted vanes and the cylinder wall, with a view to reducing power consumption and abrasion, and to produce a better vacuum in the connected device. The problem is solved, according to the invention, by the characteristics described in the claim. Accordingly, this invention provides a rotary vane pump of the general kind with a rotor eccentric in the pump cylinder, and with pivoted vanes whose pivot-feet work in axially extending recesses in the rotor, each vane being thrust against the cylinder wall by a torsion spring whose one end is retained in the rotor, its other end being retained in the vane, and in which the pivot-foot of each vane is essentially, of circular cylindrical cross section, and works in a corresponding axially extending recess in the rotor, a blind bore, which penetrates axially and centrally into the pivot-foot, containing and housing the cylindrical coil of the torsion spring. An example of the invention is illustrated in the drawing, in which: Figure 1 is a cross section of the pump, with the front cover removed. Figures 2 and 3 are axial sections of the pivotfoot of one of the vanes. The rotary vane pump, whose end-wall is known at 1 in Figure 1, has a cylindrical housing 2 in which rotates an eccentric rotor 3 with three pivoted vanes 5 spaced equally around its periphery. Each vane 5 is pivoted to the rotor 3 by a hollow-cylindrical pivot-foot 16 which works in an axial recess 4 in the rotor 3. Between each two vanes 5 there is formed a pumping chamber 6. When the pump is in operation gas is aspired through an inlet port 7 from an external device (not shown), which it is desired to evacuate, and expelled through an outlet port 8. A helical torsion spring 9 thrusts each vane 5 against the inner surface of the cylinder wall, the upper end 10 of the spring 9 being retained in a slot 12 in the rotor 3, its lower end 11 being anchored in a recess 13 situated at the bottom of a cylindrical blind bore 14 which penetrates axially and centrally into the pivot-foot 16, the cylindrical blind bore 14 containing and housing the coil 15 of the helical torsion spring 9. From the coil 15 the upper end 10 of the spring 9 projects radially outwards through a segmental passage 17 cut through the wall of the hollow pivot-foot 16, the arc of the segmental passage 17 not being great enough to bring the passage 17 into communication, at either end, with a pumping chamber 6 when the vane 5 pivots in the operation of the pump. CLAIMS

1. A rotary vane pump, with a rotor eccentric in the pump cylinder, and with the pivoted vanes whose pivot-feet work in axially extending recesses in the rotor, each vane being thrust against the cylinder wall by a torsion spring whose one end is retained in the rotor, its other end being retained in the vane, characterised in that the pivot-foot (16) of each vane (5) is essentially cylindrical, of circular cross section, and works in a corresponding axially extending recess (4) in the rotor (3), a blind bore (14), which penetrates axially and centrally into the pivot-foot (16), containing and housing the cylindrical coil (15) of the torsion spring (9).

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