GB2110759A - Rotary positive-displacement fluid-machines - Google Patents

Abstract

A gear pump comprises two pairs of internally-meshing pumping- gears 10, 12 and 14, 16 disposed one within the other. The gears may be of the gerotor-type (as shown) and the intermediate gears 12, 14 may be coupled to each other by a key 20. The innermost gear 10 may be attached to a driving shaft 18 and also to the outermost gear 16. <IMAGE>

Description

SPECIFICATION Dual capacity gear pump This invention relates to internal gear type pumps comprising inner and outer intermeshing lobed rotors which rotate about different axes at different speeds so that a number of constantly changing working volumes are formed between the lobes whereby fluid can be transferred from an inlet to an outlet as the rotors rotate.

It is known to operate such pumps in pairs with the inner rotors of the two pumps individually connected to the same drive shaft, i.e.

so that each gear set is spaced from the other axially of the drive shaft.

The object of the present invention is to provide an improved and more compact form of pump especially for use in circumstances where dual pumping capacity is required.

According to the present invention we provide a rotary fluid pump device comprising a pair of internal gear type pumps which are so arranged that the one encircles the other.

In the presently preferred embodiment, the arrangement is such that the outer gear-set is driven from the drive shaft through the agency of the inner gear-set. Thus, for example, the inner rotor of the outer gear set may be rotatably fast (or possibly integral with) the outer rotor of the inner gear set.

The two gear sets may be arranged to cooperate with respective inlets and respective outlet ports. Conceivably however they may cooperate with the same inlet port and/or the same outlet port.

One example of the invention is illustrated in the accompanying drawings in which: Figure 1 is a front elevation showing the two gear sets; Figure 2 is a diametral section through the two gear sets; and Figure 3 is a view illustrating the arrangement of the inlet and outlet ports.

As shown in Figs. 1 and 2, the pumping device comprises an inner gear set consisting of an inner rotor 10 and outer rotor 1 2 and an outer gear set consisting of an inner rotor 14 and an outer rotor 16, the whole assembly being accommodated in a housing (not shown) with the possible provision of a reversing ring to ensure unidirectional pumping of the fluid regardless of the direction of rotation of the gear sets.

Each gear set is of the n, n + 1 lobed type which is well known in the art but, in contrast with known practice, the two gear sets are arranged one within the other thereby achieving a very compact construction. The inner rotor 10 is driven by a drive shaft 1 8 and drive is transmitted from the outer rotor 1 2 to the outer gear set via a keyed connection 20 between the rotors 1 2 and 14. As shown, the rotors 1 2 and 14 are separate but it is conceivable for them to be formed integrally with each other.

The two gear sets may be so arranged that the eccentricities between their respective inner and outer rotors at least partially cancel out, i.e. so that the degree of eccentricity of the outer rotor 1 6 with respect to the inner rotor 10 is less than that between the outer rotor 1 2 and the inner rotor 10.

As shown, there are two gear-sets, one encircling the other. However, it will be appreciated that the principle could be extended to three or even more gear-sets all arranged in encircling fashion with respect to the inner gear-set or sets.

1. A rotary fluid-pumping apparatus comprising a pair of internal gear type pumps which are so arranged that the one encircles the other.

2. Apparatus as claimed in Claim 1 comprising an inner gear set and an outer gear set, the inner rotor of the inner gear set being coupled to a drive shaft and the outer gear set being coupled to the drive shaft through the agency of the inner gear set.

3. Apparatus as claimed in Claim 1 or 2 in which the inner rotor of the outer gear set is separate from the outer rotor of the inner gear set and is rotatably fast therewith.

4. Apparatus as claimed in Claim 1 or 2 in which the inner rotor of the outer gear set is integral with the outer rotor of the inner gear set.

5. Apparatus as claimed in Claim 1 or 2 in which the inner and outer gear sets are so arranged that the degree of eccentricity between the outer rotor of the outer gear set and the inner rotor of the inner gear set cancels or is substantially less than the eccentricity between the outer and inner rotors of the inner gear set.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Dual capacity gear pump This invention relates to internal gear type pumps comprising inner and outer intermeshing lobed rotors which rotate about different axes at different speeds so that a number of constantly changing working volumes are formed between the lobes whereby fluid can be transferred from an inlet to an outlet as the rotors rotate. It is known to operate such pumps in pairs with the inner rotors of the two pumps individually connected to the same drive shaft, i.e. so that each gear set is spaced from the other axially of the drive shaft. The object of the present invention is to provide an improved and more compact form of pump especially for use in circumstances where dual pumping capacity is required. According to the present invention we provide a rotary fluid pump device comprising a pair of internal gear type pumps which are so arranged that the one encircles the other. In the presently preferred embodiment, the arrangement is such that the outer gear-set is driven from the drive shaft through the agency of the inner gear-set. Thus, for example, the inner rotor of the outer gear set may be rotatably fast (or possibly integral with) the outer rotor of the inner gear set. The two gear sets may be arranged to cooperate with respective inlets and respective outlet ports. Conceivably however they may cooperate with the same inlet port and/or the same outlet port. One example of the invention is illustrated in the accompanying drawings in which: Figure 1 is a front elevation showing the two gear sets; Figure 2 is a diametral section through the two gear sets; and Figure 3 is a view illustrating the arrangement of the inlet and outlet ports. As shown in Figs. 1 and 2, the pumping device comprises an inner gear set consisting of an inner rotor 10 and outer rotor 1 2 and an outer gear set consisting of an inner rotor 14 and an outer rotor 16, the whole assembly being accommodated in a housing (not shown) with the possible provision of a reversing ring to ensure unidirectional pumping of the fluid regardless of the direction of rotation of the gear sets. Each gear set is of the n, n + 1 lobed type which is well known in the art but, in contrast with known practice, the two gear sets are arranged one within the other thereby achieving a very compact construction. The inner rotor 10 is driven by a drive shaft 1 8 and drive is transmitted from the outer rotor 1 2 to the outer gear set via a keyed connection 20 between the rotors 1 2 and 14. As shown, the rotors 1 2 and 14 are separate but it is conceivable for them to be formed integrally with each other. The two gear sets may be so arranged that the eccentricities between their respective inner and outer rotors at least partially cancel out, i.e. so that the degree of eccentricity of the outer rotor 1 6 with respect to the inner rotor 10 is less than that between the outer rotor 1 2 and the inner rotor 10. As shown, there are two gear-sets, one encircling the other. However, it will be appreciated that the principle could be extended to three or even more gear-sets all arranged in encircling fashion with respect to the inner gear-set or sets. CLAIMS

1. A rotary fluid-pumping apparatus comprising a pair of internal gear type pumps which are so arranged that the one encircles the other.

2. Apparatus as claimed in Claim 1 comprising an inner gear set and an outer gear set, the inner rotor of the inner gear set being coupled to a drive shaft and the outer gear set being coupled to the drive shaft through the agency of the inner gear set.

3. Apparatus as claimed in Claim 1 or 2 in which the inner rotor of the outer gear set is separate from the outer rotor of the inner gear set and is rotatably fast therewith.

4. Apparatus as claimed in Claim 1 or 2 in which the inner rotor of the outer gear set is integral with the outer rotor of the inner gear set.

5. Apparatus as claimed in Claim 1 or 2 in which the inner and outer gear sets are so arranged that the degree of eccentricity between the outer rotor of the outer gear set and the inner rotor of the inner gear set cancels or is substantially less than the eccentricity between the outer and inner rotors of the inner gear set.