GB2142093A - Rotary hydraulic motor or pump - Google Patents

Abstract

The motor (or pump) comprises a stationary part 1 located within a part 2 which can rotate relative to the part 1 around the axis thereof, a plurality of gear-wheels 9 being rotatably mounted on fixed shafts 5 secured to the part 1, driven by hydraulic fluid under pressure, and in meshing engagement with an annular set of gear-teeth 10 on the part 2. <IMAGE>

Description

SPECIFICATION Hydraulic motor or pump This invention relates to a hydraulic motor or pump and particularly, but not exclusively, one which is capable of controlling the shifting of very heavy loads at low speed. Preferably the hydraulic motor pump is of compact dimensions, suitable, for instance, to control the opening and closing of hatches or bulkheads, or to lift large load-carrying platforms or for other similar applications.

The means presently used for such applications consist of apparatus often taking up much space, and requiring spaced reducers, transmission gears and other devices, which results in increased costs, increased maintenance and large risk of breakdowns, etc.

According to the present invention there is provided a hydraulic motor or pump comprising a first component part provided with a plurality of rotatable gear wheels each located in a respective recess or chamber formed in the first component part and means for supplying a fluid to the recesses or chambers, and a second component part provided with a series of teeth in engagement with said gears.

The motor comprises substantially two parts, one contained inside the other, there being means in between controlling the rotation of one of said parts, as will be further described, while the second part can be secured, e.g. to a supporting structure.

Two embodiments of the invention will now be described, by way of non-limiting examples, with reference to the accompanying drawings, in which Figure 1 is a partially sectioned side view of a first embodiment of a motor according to the present invention; Figure 2 is a cross-section through the motor shown in Figure 1 and taken along a plane orthogonal to the view of Figure 1; Figure 3 is a partially sectioned side view of a particular compact second embodiment of a motor according to the present invention; and Figure 4 is a cross-section taken along a plane orthogonal to that of Figure 3.

The motor according to the invention consists essentially of two parts 1 and 2, the first being contained by the second, linked by means suitable for setting one part in motion with respect to the other part.

In the illustrated embodiment the outer part 2 is rotated while part 1 is stationary. For this reason the inner part 1 will be hereafter conveniently referred to as a "stator", and the outer part 2 as a "rotor".

The stator 1, mounted on a fixed support 3, has a substantially cylindrical shape and has a series of peripheral recesses or chambers 4 each having the section of a sector of a circle, a shaft 5 crossing each of said recesses 4.

The shafts 5 are mounted, e.g. by means of bolts 6 or the like, on end walls 7 and 8, secured to both ends of the stator 1 by means of screw 18, or the like.

On each shaft 5 there is rotatably mounted a gear wheel 9 having the same diameter size as the recess 4, so that the ends of the teeth of the gear wheel 9 engage the peripheral wall of the recess or chamber 4, during rotation. The distance between shafts 5 and the outer surface of the stator 1 is such that, for a certain part of the rotation, the teeth of the gear wheels 9 protrude from the stator 1.

The inner surface of the rotor 2 is provided with a series of teeth 10, engaging with the protruding teeth of the gear wheels 9. The outer side of rotor 2 is provided instead with a thread 11 engaging a rack or the like, fixed or otherwise connected with the load to be shifted, not shown in the drawing.

One of the end walls, and precisely that indicated at8, can consist of two coupled parts 12 and 13; a pair of annular chambers 14 and 15 being provided therein.

From each said chamber there branches off one or more ducts 16 and 17, directed outwardly and linked to a unit (not shown) for the admission and the ejection of a fluid under pressure. Each of the recesses 4 having the gear wheels 9 is connected, by means of a pair of ducts 19 and 20, with the annular chambers 14 and 15 respectively.

Ducts 19 and 20 extend from the opposite ends of each recess or chamber 4, at the height of the outer surface of the rotor 1.

In the motor there are also provided suitable sealing elements 21 of known type, and pipes 22 for collecting that part of liquid that happened to leak out.

The working operation takes place as follows: Fluid pressure is supplied e.g. along duct 16 by means of external controlling devices. The fluid reaches the annular chamber 14 and hence, passes through ducts 19, into the recesses or chambers 4, setting the wheel gears 9 in rotatory motion.

The wheel gears 9 engage the teeth 10 of the rotor 2, which is thus rotated. At the opposite end part of the recesses or chambers 4 the fluid is discharged along ducts 20, the annular chamber 15 to the return duct 17. During rotation of the rotor 2, the thread 11 which engages the outer transmission gears such as for instance a rack or the like connected with the loads to be moved, acting thereupon as an endless screw.

Obviously, to control the reverse motion, it is sufficient to circulate the fluid in the opposite direction to that described above.

Due to the thread 11, the motor acts continuously and without interruptions on a rack or like means of any length.

It appears from the above description that by the motor according to the invention, the advantages of the hydraulic systems are achieved, avoiding the stroke limits typical of piston and cylinder devices.

It is also possible, in respect to other systems of known kind, to vary continuously the speed of movement to almost zero, without the need for speed reducers.

It is apparent that the above mentioned unit may function as a pump as well as a motor, if given a rotary mechanical movement.

As already said, a particular embodiment of the invention has been described, wherein it is the outer part of the motor that is set in motion.

It is however possible, if necessary, to secure the outer part to a fixed structure; in this case it is the inner part that rotates.

If the loads to be shifted are not excessively heavy, a particularly compact version of the motor can be used, as illustrated in Figures 3 and 4, with regard to applications to travelling concrete mixers. In this case the stator 1 is mounted on fixed supports 3, while ends 7 and 8 are made of a single piece, and carry as many tooth gear wheels 9 in recesses 4 connected by a plurality of radial groove 23 each terminating at one end in a central common conduit 24, and at the other end in each of recesses 4.

In the proximity of the opposite head or end there are a like number of radial ducts 25 connected to with a central common conduit 26, and each communicating with one of recesses 4, at the opposite side to that where ducts 23 are located.

The ducts 24 and 26 are connected to hydraulic devices of known type, having the function of sending fluid under pressure to the recesses or chambers 4.

The above described unit is contained inside a cover 27, mounted on the walls 7 and 8 by means of bearings 28 or the like.

Rotor 2 is externally provided with a plurality of teeth 29 which engage corresponding teeth provided inside the cover 27, making the latter rotate.

Cover 27 is also connected, by means of bolts 30, orthe like, to the drum of a travelling concrete mixer.

A central pipe 31 starting from the area comprised between the motor and the outer cover 27 leads to a tank, not shown, for collecting the oil that may leak through the sealing elements placed between the rotor and the walls 7 and 8.

The working operation takes place as follows: The motor is secured to a supporting structure, in the present case to the frame of a travelling concrete mixer, and connected with the hydraulic devices thereof.

The oil under pressure sent to the pipe 24 passes through the branches 23, reaches recesses or chambers 4 and sets the toothed wheels in rotary motion; these in turn engage the inner set of teeth 10 of rotor 2, setting it in motion.

At the opposite side oil is discharged through ducts 25 and 26.

Upon rotor 2 there is mounted the cover 27 and, as this is fixed by bolts 30 to the drum of the travelling concrete mixer, the latter is thus kept in motion.

The oil under pressure, if any, leaking out of the recesses or chambers 4 along the area of contact between the rotor and the head walls 7 and 8, is received inside cover 27 and then collected through pipe 31.

Many changes and variations may be made which fall, however, within the scope of the present invention as defined in the appended claims.

Claims (8)

1. A hydraulic motor or pump comprising a first component part provided with a plurality of rotatable gear wheels each located in a respective recess or chamber formed in the first component part and means for supplying a fluid to the recesses or chambers, and a second component part provided with a series of teeth in engagement with said gears.

2. A hydraulic motor or pump as claimed in claim 1, in which said first component part comprises a substantially cylindrical body having a plurality or peripheral recesses or chambers for the gear wheels which are rotatably mounted on fixed shafts secured to said cylindrical body, and the second component part comprises a body external with respect to the first part and having internally said series of teeth in engagement with said gears.

3. A hydraulic motor or pump as claimed in claim 1 or claim 2, in which the second or outer component part is rotatable and provided with a screw-thread engaged with external means for the shifting of a load.

4. A hydraulic motor or pump as claimed in any preceding claim, in which there are provided in the first component part a pair of annular chambers from which branch off conduits leading to the gear recesses or chambers, one of said annular chambers being connected with a duct for the admission of fluid under pressure, and the other with a duct for the discharge of fluid.

5. A hydraulic motor or pump as claimed in any preceding claim, in which the head or end walls of the first component part are made of a single piece and in each of them there are provided ducts for the supply and discharge of the fluid, and a central common duct from which branch off substantially radial ducts leading each to one of the recesses or chambers.

6. A hydraulic motor or pump as claimed in any preceding claim, in which the rotor-stator unit is enclosed in a casing for collecting the oil that flows out from the recesses or chambers.

7. A hydraulic motor or pump as claimed in claim 6, in which means are provided to connect said casing to outer means to be rotatably driven.

8. A hydraulic pump or motor substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 or Figure 3 and 4 of the accompanying drawings.