WO2010081506A1

WO2010081506A1 - Hydrostatic variator of velocity having radial pistons

Info

Publication number: WO2010081506A1
Application number: PCT/EP2009/008628
Authority: WO
Inventors: Stefano Speggiorin
Original assignee: Var-Spe S.P.A.
Priority date: 2009-01-19
Filing date: 2009-12-03
Publication date: 2010-07-22
Also published as: IT1393224B1; ITVI20090004A1

Abstract

The variator according to the finding comprises a pump having radial pistons (6), with variable eccentricity, a hydraulic motor (7), also having radial pistons and a central distributor (8) that, through the support bushings (9 and 10) of the rotors, places the radial cylindrical cavities of the pump unit in communication with those of the hydraulic motor unit. By modifying the eccentricity of the pump the flow rate of the liquid of the latter is modified, thus determining the variation in the number of turns of the hydraulic motor.

Description

Title: Hydrodynamic variator of velocity having radial pistons

Description

The present finding concerns a hydrodynamic variator of velocity having radial pistons, according to the general part of claim 1.

With regard to the state of the art, we quote the devices described in document GB-A 1190114 (for the sake of simplicity identified with type 11-14, in the rest of the present document) and in document EP-A-0428192 (for the sake of simplicity identified with type A2-A12 in the rest of the present document), to the same applicant as the present application.

The first document describes a device comprising a pump having radial pistons and a hydraulic motor having radial pistons; between these two elements, connected together by a central shaft, a circulation of liquid is established through the channels of the shaft itself. The variable eccentricity of the pump and/or of the hydraulic motor allows the variations in speed of the driven shaft to be obtained.

The second document indicated above describes a device comprising a pump having radial pistons and a hydraulic motor, also having radial pistons, with a system of front distributors suitable for placing the radial cylindrical cavities of pump and motor in communication. By varying the eccentricity of the pump a variation in output speed is obtained.

The quoted variators, whilst having achieved considerable success in terms of their practical use, in particular in the field of small and medium powers, have encountered some drawbacks, which we wish to eliminate with the variator according to the present finding, which introduces some clear advantages both in terms of simplicity of production, and in terms of the basic characteristics for the commercial market.

With regard to type 11-14, a limiting factor is the low modularity with which it is made: very few components can be used for more than one size (power).

Some important characteristics for the installation (two-way entry, assembly position) cannot be modified, apart from by completely dismounting the variator.

With regard to type A2-A12 the front distribution system obliges the coupling of many components with very narrow tolerances, often causing the need, in the testing step, to dismount and test some components, and then mount and once again test the variator.

Still in type A2-A12 the opening of the distributor plate as maximum pressure valve is not guaranteed.

Another drawback, encountered particularly in type 11-14, consists of the high production cost, due to the complexity of the pieces and the low modularity thereof.

All of these drawbacks are eliminated in the improved variator according to the finding, which is quieter and more cost-effective than the previous one thanks to the characteristics of the characterising part of claim 1.

Its most obvious advantages are described hereafter.

The variator has been designed with special attention for its modularity, to minimise the components able to be used for only a single size (power), allowing the use of the overwhelming majority of the pieces on four current types of variators. In short, there is a base power module, identical for all four types, for which kits are used for the entry and exit covers, relative to the power used. The feet are removable, allowing interchangeability with the previous variators or flexibility of choice not possible before. All of this determines a substantial simplification from the point of view of production, with a consequent decrease in production costs.

On the improved variator according to the finding there is, mass-produced, a system for adjusting the maximum pressure (thus the maximum torque) of the liquid, present only upon request on types 11-14 and A2-A12 (on these an external block was necessary, which suffers more from leaks of pressurised fluid).

Another simplifying characteristic is the coupling between hydraulic unit (pump and hydraulic motor) and input and output shaft. In type 11-14 it was ensured by a fit-in coupling joint, whereas in series A2-A12 the shaft is "planted" in the hydraulic unit. In the variator according to the finding the coupling takes place through two hardened cylindrical rollers that connect the two elements. The advantage of this solution consists of the fact that there is one expensive piece less than types 11-14 and there is greater flexibility in producing a special output shaft than types A2-A12 (for which it was necessary to plant the shaft in the rotor and rectify the whole thing, thus forcing very high costs for shafts specifically requested by the client).

In the output shaft the function of a polar wheel (phonic wheel, with holes for reading the frequency that acts as sensor for the speed) is already integrated, which allows a simplification of the pieces, a decrease in costs and a greater flexibility for the client, who can add the sensor later on.

The assembly position is universal, without the need for any modification on the variator (in type 1 1-14 it was necessary to proceed to the complete disassembly of the variator, whereas in type A2-A12 it was necessary to invert two fixed dowels on the fusion of the input cover). On the mass-produced model there is the system for the two-way rotation of the input shaft: this allows the client to have greater flexibility of operation and less drawbacks in the installation step (an incorrect rotation in input causes the liquid not to be drawn up, with possible seizure of the system, due to the absence of lubrication).

The speed adjustment controls are modular (the control can be used for all sizes), whereas currently in type 11-14 they cannot; this also involves a substantial simplification of production.

The hydrodynamic variator of velocity having radial pistons according to the finding is defined by the characterising part of claim 1.

The attached drawings, provided as an example and not for limiting purposes, make it possible to better understand the finding, its characteristics and the advantages that it gives.

In particular:

- fig. 1 represents an axial longitudinal section of the device according to the finding.

- figs. 2 - 6 represent cross sections made according to the planes indicated in Fig. 1 (A-A, B-B, C-C, D-D, E-E respectively).

As can be seen from the figures, the drive shaft 11 is connected and firmly fixed to the driven shaft 12 by a hydrostatic transmission. The drive shaft 1 1 is firmly fixed to the rotor of the pump 6, whereas the driven shaft 12 is firmly fixed to the hydraulic motor 7. The drive shaft 11 is supported and rotates through the shaft of the electric motor, whereas the rotor 6 is supported and rotates, through the bushing 9, on the distributor shaft 8. The driven shaft 12 is supported and rotates on the bearings 13 and 14, whereas the rotor 7 is supported and rotates, through the bushing 10, on the distributor shaft 8.

The rotor of the pump 6 comprises radial cylindrical cavities, in which piston 15 move. These pistons are moved outwards by the centrifugal force generated by the rotation given to the drive shaft, strike against the inner ring 16 of the rolling bearing 18, the outer ring 17 of which is firmly fixed to the manoeuvring ring 23, in turn firmly fixed to the carcass 1, still being suitable for being moved transversally with respect to the above, as can be seen in fig. 2. In an analogous way the rotor of the hydraulic motor 7 (Fig. 3) has radial cylindrical cavities, inside of which run the pistons 19, which, being moved outwards by the pressure of the liquid, stop against the inner ring 20 of the rolling bearing 21, the outer ring 22 of which is firmly fixed to the carcass 1. At least one of the two rolling bearings 18 and 21 can have a variable eccentricity.

For example, in the embodiment illustrated in Fig. 2, the outer ring 17 of the bearing 18 is fixed to the manoeuvring ring 23 pivoted on the support pin 24 and it can move transversally to the longitudinal axis of the machine, through the control system consisting of the round-headed pin 25, held by the sleeve 26. The latter has a threaded hole in which the screw 27 is mounted, the cylindrical parts of which 29 and 30 are suitable for rotating inside the openings formed on the carcass 5, being able to be set in rotation by the handwheel 28, actuated by hand. A variation in eccentricity of the bearing 18 leads to a corresponding variation in maximum stroke carried out by the piston 15 inside the corresponding cylindrical cavities and. consequently, a variation in displacement of each piston. In the example embodiment illustrated in the attached drawings the hydraulic motor 7 has a constant eccentricity, whereas the pump 6 has a variable eccentricity, in both directions transversal to the longitudinal axis of the machine.

Nevertheless, it should be understood that the hydraulic motor 7 can also be made with variable eccentricity through an arrangement similar to that of the pump 6.

Each of the radial cylindrical cavities of the pump 6 is in communication, through the openings on the bushings 31, with the inner channels of the distributor shaft 8. The same applies to the hydraulic motor 7, in which analogous openings on the bushings 32 allow the communication between the radial cylindrical cavities and the inner channels of the distributor shaft 8.

Said channels, or pipes 33 are in communication with the chamber 54 through the two non-return valves 47 and 48. The chamber 54 is placed in communication through suitable pipes with the delivery chamber of the feeding pump 55 (Fig. 5).

The non-return valves 47 and 48 act alternatively, according to the pipe that has the pressurised liquid; they allow the liquid to go from the chamber 54 into the pipes 33, but not vice-versa (the pressure in the delivery pipes 33, from pump to hydraulic motor, is greater than the pressure generated by the feeding pump 55, whereas in the return ones it is less).

The feeding pump consists of a rotor having radial cavities 55 and rollers 56. It is set in rotation by the drive shaft 11 , through the bushing 9 firmly fixed to the pump itself by the key 57 (Figure 5).

The intake chamber 65 of the feeding pump is connected with the low part of the carcass I (which acts as a tank) through the intake pipe 64 (Figure 6). The rotor of the pump 55 can rotate both in the clockwise and anti-clockwise direction, according to the rotation of the drive shaft 11. By rotating in the clockwise direction (looking at figure 5), the liquid is sucked through the non-return valve 60, while the non-return valve 59 stays closed. In this case the compression area of the pump is one half greater, for which reason the chamber 62 becomes the delivery chamber, through the non-return valve 58, while the valve 61 stays closed (in the case of anti -clockwise rotation of the rotor 55 of the pump there is the opposite situation: the valve 59 is for intake, while the valve 60 stays closed; the delivery chamber becomes 63, with the delivery valve 61, while the valve 58 stays closed).

With reference to Figure 4, a valve 43, kept closed by a spring 44, associated with a hollow barrel 42 fixed onto the carcass allows the excess liquid generated by the pump 55 to be discharged in a case of the variator that acts as a tank. A pipe 66, closed by a threaded plug 67, communicates with the delivery chamber 54 of the feeding pump; this allows a manometer to be assembled to control the pressure of the liquid generated by the pump and allows pressurised liquid to be taken for a possible hydraulic system for adjusting the speed of the variator (instead of the handwheel).

The valves, consisting of the balls 34, 48, the barrels 35, 37, 53, 49 and the springs 50 and 36, determine the maximum pressure of the liquid in the circuit of the pump and of the hydraulic motor. These two valves are kept closed by the calibrated springs 50 and 36, allowing the liquid to be discharged in the body, when for example, following a sudden stop of the hydraulic motor, the pressure of the liquid itself is in danger of reaching excessive values. It is possible to act on the outside to adjust such valves and thus determine the opening pressure o value, through the adjustment screws (38 and 52).

The operation of the variator can easily be understood through the examination of the attached drawings.

When the drive shaft is set in rotation, the motion is also transmitted to the feeding pump 55, which takes in the liquid from the body through the channel 64 and places it under pressure in the working circuit of the variator through the valves 46 and 47. After a few turns, the pressurised liquid completely fills the cylindrical cavities beneath the pistons 15 of the pump 6 and 19 of the hydraulic motor 7. The latter starts to turn in the opposite direction to that of the pump 6, if its eccentricity coincides with that of the pump itself.

With the clockwise direction of rotation, (looking at fig. 2), the pistons 15 of the upper semi-circle move outwards, under the action of the centrifugal force and the pressure of the liquid generated by the feeding pump. In the lower semicircle, on the other hand, there is a step of compression of the liquid, by the pistons 15, which, forced back in by the eccentricity, compress the liquid present in the cylindrical cavities below, which through the pipes 33 of the distributor shaft 8 is sent to the hydraulic motor 7. In the latter the exact opposite occurs: the pressurised liquid arriving from the pump 6 pushes at the base of the pistons 19, making them come out during the lower semi-circle. The component of the force perpendicular to the axis of the piston is transmitted to the output shaft 12, firmly fixed to the hydraulic motor 7 through the pins 69.

By varying the eccentricity of the pump the amount of liquid sent is modified, thus causing a variation in the number of turns of the hydraulic motor. In particular, an increase in eccentricity of the pump leads to a greater flow rate of hydraulic liquid and consequently an increase in the number of turns of the hydraulic motor.

On the other hand, a reduction in eccentricity of the pump correspondingly causes a decrease in the number of turns of the hydraulic motor.

When the eccentricity of the pump is at zero, the hydraulic motor stops; whereas when the eccentricity is reached on the opposite side, the direction of rotation of the hydraulic motor inverts.

According to another particular embodiment of the invention, it is foreseen for the eccentricity of the hydraulic motor to be able to vary, in order to obtain a greater number of turns at the driven shaft than that of the drive shaft, both in one direction and the other.

Of course, the variator can take on different embodiments to the one described.

For example, the pump can be separate from the hydraulic motor, foreseeing a connection through piping.

Moreover, it is possible to foresee for the output of the driven shaft to be oriented perpendicular to the drive shaft.

Claims

1. HYDRODYNAMIC VARIATOR OF VELOCITY HAVING RADIAL PISTONS, of the type comprising a pump (6) and a hydraulic motor (7), both arranged on a frame or body (1), equipped with rotary pistons (15 and 19), which, forced outwards by the pressure of the liquid, crash against the inner rings (16 and 20) of the rolling bearing (18 and 21) with variable eccentricity, the variator being characterised in that the pipes (33) of the distributor shaft (8) place the radial cylindrical cavities in communication under the pistons (15 and 19), through the openings (31 and 32) present on the bushings (9 and 10), which support the pump (6) and the hydraulic motor (7) on the distributor shaft (8), which allows the hydraulic motor (7) to rotate in the same direction or in the reverse direction with respect to the pump (6), according to an inverse or identical eccentricity with respect to that of the aforementioned pump (6), as well as in that a stemming or feed pump (55) is connected to an intake pipe (64) at the case of the variator that acts as a tank.

2. VARIATOR, according to claim 1, characterised in that a manoeuvring ring (23) is pivoted on a support pin (24) fixed on the body (1), said ring having the outer track (17) of a rolling bearing (18) fitted onto it, on the inner track (16) of which the pistons (15) of the pump (6) are placed in contact, the manoeuvring ring (23) being able to move transversally with respect to the rotation axis of the variator by means of an adjustment system consisting of a round-headed pin (25), held by a sleeve (26), in the threaded opening of which a threaded shaft (27) is mounted, controlled by hand through a handwheel (28), thus generating a variation in eccentricity of the bearing (18) and, consequently, a variation in the maximum stroke carried out by the pistons (15) and thus a variation in displacement of each piston.

3. Variator, according to any one of claims 1 and 2, characterised in that the valves (35 and 49) determine the maximum pressure of the liquid in the circuit, said valves being able to be externally calibrated through adjustment screws (38 and 52), the valves (46 and 47) allowing the pressurised liquid, coming from the feeding pump, to enter into the pipes (33) of the distributor shaft (8) and acting alternatively according to whether the hydraulic motor (7) rotates in the same or opposite direction with respect to the pump (6).

4. VARIATOR, according to any one of claims 1 to 3, characterised in that the manoeuvring ring (23) for adjusting the eccentricity of the pump (6), as well as the one with which the hydraulic motor (7) is possibly equipped, is pivoted on the support pin (24) and is able to be moved by the control system, in order to modify the eccentricity of the pump (6) and possibly that of the hydraulic motor (7) from a maximum position to one in the opposite direction, thus allowing the rotation speed of the hydraulic motor in one direction or the other to be modified, with respect to that of the pump.

5. VARIATOR, according to any one of claims 1 to 4, characterised in that the pump (6) is fixedly connected to the drive shaft (11) and the pipes (33) of the distributor shaft (8) are connected to it through radial openings (31) present on the support bushing (9) of the pump itself.

6. VARIATOR, according to any one of claims 1 to 5, characterised in that the hydraulic motor (7) is fixedly connected to the driven shaft (12) and the pipes (33) of the distributor shaft (8) are connected to it through radial openings (32) present on the support bushing (10) of the hydraulic motor itself.

7. VARIATOR, according to any one of claims 1 to 6, characterised in that it foresees the use of a group of components (in particular body (1), pump (6), hydraulic motor (7), distributor shaft (8), supply pump (59) and all of the components necessary for the hydraulic working circuit and the feeding circuit) as base power module for different powers, together with some kits of covers and shafts with variable dimensions, in particular also comprising flangings for the entry part, so as to define the desired configuration, with reference to the power installed.

8. VARIATOR, according to any one of claims 1 to 7, characterised in that the driven shaft (12) has a radially perforated disc inside of it for the use of a proximity sensor or a voltage generator, suitable for supplying a value proportional to the speed of the shaft itself.

9. VARIATOR, according to any one of claims 1 to 8, characterised in that the drive shaft (11) and the driven shaft (12) are fixedly connected, respectively, to the pump (6) and to the hydraulic motor (7) through pins (68, 69).

10. VARIATOR, according to any one of claims 1 to 9, characterised in that the feeding pump 55, fixedly connected to the drive shaft (11) and able to rotate in both directions, in any case generating the intake to place the liquid in circulation.