GB1579928A - Hydraulic machines - Google Patents

Hydraulic machines Download PDF

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Publication number
GB1579928A
GB1579928A GB2712876A GB2712876A GB1579928A GB 1579928 A GB1579928 A GB 1579928A GB 2712876 A GB2712876 A GB 2712876A GB 2712876 A GB2712876 A GB 2712876A GB 1579928 A GB1579928 A GB 1579928A
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GB
United Kingdom
Prior art keywords
gears
hydraulic
gear
stage
shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB2712876A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Secretary for Industry
Original Assignee
UK Secretary for Industry
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by UK Secretary for Industry filed Critical UK Secretary for Industry
Priority to GB2712876A priority Critical patent/GB1579928A/en
Publication of GB1579928A publication Critical patent/GB1579928A/en
Expired legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C11/00Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations
    • F04C11/001Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations of similar working principle

Description

(54) IMPROVEMENTS IN OR RELATING TO HYDRAULIC MACHINES (71) I, SECRETARY OF STATE FOR IN DUSTRY, London, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following state ment :- This invention relates to hydraulic machines and, more particularly, concerns hydraulic gear pumps and gear motors having at least two pairs of meshing gears.
It is known to provide hydraulic pumps and motors in which energy conversion is effected by means of a pair of meshing gears.
Thus, in hydraulic gear pumps a pair of meshing pumping gears can be shaft-driven to provide an output flow of fluid. On the other hand, in hydraulic gear motors a pair of meshing gears can be driven by a flow of hydraulic fluid to produce as an output rotation in a shaft.
In a simple hydraulic gear pump, having a single pair of pumping gears, the pumping gears mesh together and rotate within a close-fitting housing to carry hydraulic fluid between the gears and the housing from an input port to an output port. In one common arrangement, two externally-toothed pumping gears are contra-rotatable. In another common arrangement, often called an internal gear pump, an externallytoothed, relatively small gear rotates within and meshes with a relatively large internally toothed gear. In this latter arrangement, the axes of the two gears are spaced from one another and a crescent-shaped part of the housing lies between the two gears. Transfer of fluid from the input port to the output port takes place in the cavities between the teeth of the gears and the crescent-shaped member.
The output flow of fluid from gear pumps varies cyclically with the rate of passage of gear teeth across the output port. When a plurality of pairs of pumping gears are arranged in series to provide a multi-stage gear pump, it has been arranged that the output flow of each of the stages varies in step with the ability of the next successive stage to receive the flow, i.e. when the output pressure of a stage is high, the next stage is arranged so as to be best able to receive an input flow of fluid.
This has introduced the constraint that in multi-stage pumps, all the pairs of gears, i.e. all the stages, have been in phase with one another. Similar considerations have applied to the design of multi-stage gear motors. In the past, attempts have been made to reduce the liquid-borne noise of hydraulic gear pumps and motors by paying special attention to the design of gear profiles and other mating surfaces, but this approach has met with limited success.
This invention seeks to provide hydraulic machines which provide less liquid-borne noise than the known machines.
According to the present invention there is provided a hydraulic machine having at least a first pair and a second pair of meshing gears, each pair being mounted for rotation within a respective, distinct, close-fitting housing and serving to separate a high pressure volume which is adapted to contain high pressure fluid in use from a low pressure volume for containing low pressure fluid in use, characterised in that the machine has a single pressure volume common to the first and second pairs of gears, and in that the engagement or disengagement of successive teeth ofthe first pair of gears at points adjacent the high pressure volume is out of phase with that of successive teeth of the second pair of gears by a fraction of a tooth pitch.
The hydraulic machines of the invention will generally be either hydraulic pumps or hydraulic motors. While this specification describes, in the main, pumps rather than motors, it will be appreciated that the invention can readily be applied to hydraulic motors, as will be apparent to those skilled in this art. Hydraulic motors according to the invention can be constructed so as to provide a torque which fluctuates with time with a smaller amplitude than does the torque produced by the known hydraulic gear motors.
The remainder of the specification refers to pumps.
In one convenient arrangement, a single stage hydraulic gear pump according to the invention is provided with three similar pairs of pumping gears arranged in parallel, with one gear of each pair being carried on a common shaft, It is arranged that the three similar gears on the shaft are out of phase with adjacent gears on the shaft by equal fractions of the tooth pitch so that when the shaft is rotated the outputs from the three stages are out of phase with each other. A multi-stage pump can be provided by connecting two or more of these 3-pair stages in sequence. Each stage need not be of three pairs but can be, for example, two or four pairs of pumping gears arranged out of phase.
Replacement of a gear pump in which all the pairs of pumping gears are in phase with a gear pump according to the present invention has been shown considerably to reduce liquid-borne noise. By way of example, comparison of liquid-borne noise at the fundamental frequency characteristic of an "in phase" pump with the noise at the same frequency in one specific pump according to the invention has shown a reduction of up to 45 db. Furthermore, the liquid-borne noise in the latter pump at multiples of this fundamental frequency has been found to be very much smaller than the liquid-borne noise of the in-phase pump at its fundamental frequency.
For a better understanding of the invention and to show more clearly how the same can be carried into effect, reference will now be made by way of example to the accompanying drawings, in which; Figure 1 is a transverse section of a single stage internal gear pump, Figure 2 is an end view of a shaft and drive gears of a single stage internal gear pump according to the present invention, and Figure 3a and 3b are block diagrams of three-stage gear pumps which are known, and according to the invention, respectively.
Figure 1 shows a shaft 2 carrying a drive gear 4 keyed to it with a key 6. The teeth of the drive gear 4 mesh with the teeth of an internally toothed annular gear 8 which is rotatable within a housing 10. The housing 10 has a crescent-shaped member 12 which is contacted on one side by the gear 4 and on the other side by the gear 8. The member 12 divides the space between the gears 4 and 8 into an input chamber 14 constituting a low pressure volume and an output chamber 16 constituting a high pressure volume. An input conduit 20 communicates with the input chamber 14 and an output conduit 22 communicates with the ouput chamber 16.
When the pump is in use the shaft 2 is rotated anti-clockwise and fluid is supplied along input conduit 20 to the input chamber 14 at pressure P. The motion of the gears 4 and 8 carries fluid past the crescent 12 into the output chamber 16. Fluid cannot return to the input chamber between the teeth of the gears because of their intermeshing. Also, the housing 10 fits snugly around the gears to prevent passage of fluid around the sides of the gears. With an impedance to flow in the output conduit 22 the pressure can build up to pressure P1 in the output chamber 16 as fluid is continually transferred to it by the teeth of the gears 4 and 8.
By reversing the sense of rotation of the shaft 2, fluid can be pumped from the output chamber 16 to the input chamber 14 if it is supplied along the output conduit 22.
In Figure 2 there is shown a shaft 2 on which are keyed at spaced intervals three drive gears 4a, 4b and 4c. The shaft and drive gears can be installed within three distinct housings arranged in parallel along the shaft with an input manifold and an output manifold connected to all three housings.
The drive gears 4a, 4b and 4c mesh with internally toothed, driven gears one within each housing.
It is to be noted that the three gears 4a, 4b and 4c are in phased relationship on the shaft 2. That is, the teeth of gears 4a, 4b and 4c are displaced circumferentially from one another by a fraction of a tooth pitch. In the embodiment shown, the teeth of gears 4a, 4b and 4c are displaced by a similar amount from each other. The internally toothed gears of the three housings are rotatable about a common axis so that the meshing of the various teeth of the gears 4a, 4b and 4e with those of the internally toothed gears occurs in a phased relationship corresponding to that in which the drive gears are mounted on the shaft.
It will be obvious that a phased meshing of gear teeth can be achieved by aligning the teeth of the drive gears on the shaft 2 and staggering the rotational axes of the internal gears at different angular positions relative to the shaft 2.
Figure 3a shows a conventional threestage gear pump, in which the output from a first stage 30 at pressure P1 is fed to a second stage 32. The output from the second stage 32 is fed at pressure P2 to a third stage 34 whose output is at pressure P3. The block diagram is purely schematic and in practice the three stages are all carried on the same shaft with the three drive gears on the shaft with their teeth in strict alignment.
Figure 3b shows a three-stage gear pump according to the present invention, with each stage having three pairs of pumping gears.
The first stage has three pairs of pumping gears 36, 38 and 40 with their drive gears arranged on a single shaft in the manner shown in Figure 2. The second and third stages are similar, but as in the case of the conventional pump, they can be carried on the same shaft rather than as the stages are shown in the diagram.
A two-stage pump according to the invention has been operated at a shaft speed of 1800 rpm giving an output flow of 25 Imperial galls per minute at a pressure of 3,000 pounds per sq. inch. Another embodiment having a larger capacity has delivered 75 Imp. galls per minute at somewhat lower shaft speeds.
The accumulated store of published design data relating to gear pumps and motors can be relied upon to assist in construction and operation of machines according to the present invention. It is considered that sufficient of such data will be known to those skilled in this art to make it unnecessary to include in this specification any further description of how to put the invention into effect.
WHAT I CLAIM IS: 1. A hydraulic machine having at least a first pair and a second pair of meshing gears, each pair being mounted for rotation within a respective, distinct close-fitting housing and serving to separate a high pressure volume which is adapted to contain high pressure fluid in use from a low pressure volume for containing low pressure fluid in use, wherein the machine has a single high pressure volume common to the first and second pairs of gears, and wherein the engagement or disengagement of successive teeth of the first pair of gears at points adjacent the high pressure volume is out of phase with that of successive teeth of the second pair of gears by a fraction of a tooth pitch.
2. A hydraulic machine as claimed in claim 1, having at least three pairs of meshing gears with each of the pairs being out of phase with the others by the same fraction (or multiple thereof) of a tooth pitch.
3. A hydraulic machine as claimed in claim 1 or 2, constructed and arranged for use as a hydraulic pump.
4. A hydraulic machine as claimed in claim 3 arranged so as to provide one stage of a multi-stage hydraulic pump.
5. A two-stage hydraulic pump in which each stage is a hydraulic machine as claimed

Claims (1)

  1. in claim 3.
    6. A hydraulic machine substantially as hereinbefore described with reference to Figs. 1 and 2, or Fig. 3b of the accompanying drawings.
GB2712876A 1976-06-29 1976-06-29 Hydraulic machines Expired GB1579928A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2712876A GB1579928A (en) 1976-06-29 1976-06-29 Hydraulic machines

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB2712876A GB1579928A (en) 1976-06-29 1976-06-29 Hydraulic machines
DE19772729208 DE2729208A1 (en) 1976-06-29 1977-06-29 HYDRAULIC GEAR MACHINE

Publications (1)

Publication Number Publication Date
GB1579928A true GB1579928A (en) 1980-11-26

Family

ID=10254678

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2712876A Expired GB1579928A (en) 1976-06-29 1976-06-29 Hydraulic machines

Country Status (2)

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DE (1) DE2729208A1 (en)
GB (1) GB1579928A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2311334A (en) * 1996-03-21 1997-09-24 Ultra Hydraulics Ltd Gear pump with two out of phase gears on a common shaft.
US6612822B2 (en) * 2001-07-09 2003-09-02 Valeo Electrical Systems, Inc. Hydraulic motor system
CN103443465A (en) * 2011-03-23 2013-12-11 金钟文 Rotational clap suction/pressure device

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5466131A (en) * 1994-03-22 1995-11-14 Micropump Corporation Multiple-chamber gear pump with hydraulically connected chambers
US5702234A (en) * 1995-12-01 1997-12-30 Micropump, Inc. Fluid pump with bearing set having lubrication path

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2311334A (en) * 1996-03-21 1997-09-24 Ultra Hydraulics Ltd Gear pump with two out of phase gears on a common shaft.
US6612822B2 (en) * 2001-07-09 2003-09-02 Valeo Electrical Systems, Inc. Hydraulic motor system
CN103443465A (en) * 2011-03-23 2013-12-11 金钟文 Rotational clap suction/pressure device

Also Published As

Publication number Publication date
DE2729208A1 (en) 1979-05-17

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PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee