WO2010003502A2

WO2010003502A2 - A rotary displacement pump with a dual driving gear

Info

Publication number: WO2010003502A2
Application number: PCT/EP2009/004191
Authority: WO
Inventors: Leonardo Cadeddu
Original assignee: Vhit S.P.A. Societa Unipersonale
Priority date: 2008-06-16
Filing date: 2009-06-08
Publication date: 2010-01-14
Also published as: ITTO20080466A1; WO2010003502A3

Abstract

A rotary displacement pump (P) including a rotor (R; 3), wherein the rotor (R; 3) is provided at both its ends with coupling means (M1, M2; 1, 2) in order to be driven by two different energy sources (T, E), and in which at least one (M1, M2; 1, 2) of these coupling means includes a one-way transmission means (L; 1), namely a so-called freewheel A sole one-way transmission means may be associated with only one of the coupling means of the rotor (R; 3), or else one-way transmission means may be associated with both coupling means of the rotor (R; 3) A thermal traction engine (T) of a vehicle can be coupled with the rotor (R; 3) of the pump (P) through a one-way transmission means, and an electric driving motor (E) can be coupled to the rotor (R; 3) of the pump (P), either in a permanent manner or through a one-way transmission means (L; 1, 2). The electric motor (E), when coupled in a permanent manner, can be used when needed as a generator, in order to contribute to the charge of batteries. The one-way transmission means (L; 1, 2) can be a positive driving means or it can be a friction driving means, possibly subject to a torque limitation.

Description

DESCRIPTION

A ROTARY DISPLACEMENT PUMP WITH A DUAL DRIVING GEAR

FIELD OF THE INVENTION

The subject of this invention is a rotary displacement pump equipped with arrangements intended to allow its operation by two different energy sources. This pump is mainly suitable for use in the automotive field, and particularly as a vacuum pump, however it is also suitable for other applications, for example as a pump for hydraulic servosteering, as a pump for lubricating oil, as a hydraulic pump for the vehicle suspension, as a compressor for the pneumatic braking, as a pump for the conditioning plant, as a pump for the water of the heating plant, and so on.

BACKGROUND OF THE INVENTION

In the rotary displacement pumps installed on conventional vehicles driven by a thermal engine, in general the pump is operated by the vehicle thermal engine, but in the hybrid vehicles, operated alternatively by a thermal engine and by an electric motor or even by both motors, it is needed that the operation of the pump is released from the rotation of the thermal engine, and therefore the pump is operated by an own electric motor even when the ther- mal engine is operative. This involves several drawbacks, as the need to use an electric motor suitable for continuous operation, and therefore subject to a relatively costly design, an'd the continuous consumption of electric energy coming from the vehicle electric batteries, and this though the periods in which the vehicle is operated in electric mode being, in the practice, limited. As an alternative, it is possible to foresee two pumps, the one operated by the thermal traction engine, and the other operated by an electric motor, but this solution is costly and cumbersome.

Moreover, the operation of the pump by the thermal engine is satisfactory when the thermal engine works at a relatively high rate, but it can be- come inadequate when the thermal engine works at a very low rate. Besides, in several cases, negative or even very harmful consequences are verified in the case that the pump is operated in a rotation direction opposite the rotation direction that is preestablished for its operation. When the pump is operated by a thermal engine, this case may happen each time the thermal engine is subjected to a counterrotation, and such counter- rotation of the engine may take place in several specific circumstances.

SUMMARY OF THE INVENTION

This invention has the purpose of solving the above mentioned problems, mainly with reference to hybrid vehicles, but in general also with refer- ence to conventional vehicles.

The principle of the invention is to provide for the rotary displacement pump the possibility of being operated by two different energy sources, in the practice by a thermal engine and by an electric motor, without giving rise to negative consequences. According to the invention, a rotary displacement pump including a rotor is characterized in that said rotor is provided at both its ends with coupling means in order to be driven by two different energy sources, and in that at least one of said coupling means includes a one-way transmission means, namely a so-called freewheel. In this manner, the pump can be coupled on one side to a thermal traction engine through the coupling means including the one-way transmission means, and can be coupled on the other side to an electric motor.

Many advantages result from this arrangement. In the case of a hybrid vehicle, the pump can usually be operated by the thermal traction engine, as in a conventional vehicle, and only during the periods of electric vehicle operation should be made operating the electric motor for driving the pump. Therefore, this electric motor driving the pump does not require to be designed for a continuous operation, and the consumption of electric energy coming from the batteries for feeding the electric motor is limited to the periods of electric operation of the vehicle. But, also when the thermal traction engine works at a very low speed, the electric motor driving the pump can be put in auxiliary operation, thus ensuring a complete functionality of the pump even at the low rates of the thermal engine. This feature can be exploited with ad- vantage also in a conventional vehicle. In all cases in which the electric motor drives the pump, both in the absence of operation by the thermal engine and at the low rates of the thermal engine, the pump can be operated at a normal speed without transmitting a torque to the thermal engine, thanks to the pres- ence of the one-way transmission means which allows the pump to rotate at a speed larger than the rotational speed of the coupling means connected to the thermal engine.

Moreover, the presence of the one-way transmission means prevents any operation of the pump in the direction opposite the rotation direction that is preestablished for its operation, when for any reason the thermal engine is subjected to a counterrotation. In this manner ceases any risk of harmful consequences produced by the pump counterrotation.

According to a possible embodiment, said one-way transmission means is associated with only one of the coupling means of the rotor. In the practice, only a thermal traction engine is coupled to the pump rotor through a one-way transmission means, whereas a driving electric motor is coupled to the pump rotor in a permanent way. When the pump is operated by the thermal engine, the electric motor is driven too, but this fact does not entail harmful consequences in view of the reduced mechanical resistance opposed by a freely driven electric motor. On the other hand, considering the reversibility of the electric motors, in this case it is also possible to use the thus driven electric motor as an electric generator in order to contribute to the charge of the batteries.

According to another embodiment, on the contrary, a one-way transmis- sion means is associated with each coupling means of the rotor. In this case, the operation of the pump by the one or the other energy source is completely independent from the existence and the condition of the other energy source.

The one-way transmission means associated with one or both the rotor coupling means can be a positive driving means. In this case, the one-way transmission means can comprise a rotor cavity haying one or more peripheral recesses, and a corresponding number of flaps housed in said rotor cavity, articulated to the coupling means, pushed outwards by springs and so arranged as to engage said recesses when the coupling means rotates in the preestab- lished direction for operation of the pump, thus establishing a motion trans- mission towards the rotor, and as to retract inwards, thus breaking off the mo- tion transmission, when the coupling means rotates in the direction opposite the rotation direction preestablished for the pump operation.

As an alternative, the one-way transmission means associated with one or both the rotor coupling means can be a friction driving means. In this case, the one-way transmission means can comprise a cylindrical rotor cavity and a member, connected to the coupling means, having peripheral lanes shaped as spiral sectors, wherein are housed roll elements arranged for wedging between said lanes and the wall of said cylindrical cavity when the coupling member rotates in the direction preestablished for the pump opera- tion, thus establishing a motion transmission towards the rotor, and for ceasing said wedging and breaking off the motion transmission when the coupling member rotates in the direction opposite to the direction preestablished for the pump operation.

In this case, the one-way transmission means can be subject to a torque limitation, the component parts thereof being arranged and sized in such a manner that the motion transmission gives rise to a sliding when the driving torque is excessive, thus protecting the pump against overcharges.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, objects and advantages of the subject of the present invention will more clearly appear from the following description of some embodiments, being not limiting examples, with reference to the accompanying drawings, wherein:

Figure 1 represents in an entirely diagrammatic manner the principle on which the invention is based. Figure 2 is a diagrammatic representation of the side view of a pump embodied according to the invention.

Figure 3 shows a cross section of a coupling means including a one-way transmission means, taken along line Ill-Ill of Figure 2.

Figure 4 shows a cross section of a coupling means including a one-way transmission means, taken along line IV-IV of Figure 2.

Figure 5 shows a cross section of a coupling means including a one-way transmission means, taken along a line parallel to line IV-IV of Figure 2. Figure 6 shows an axial view of a coupling means including a one-way transmission means, according to a first embodiment, represented in the condition of motion transmission.

Figure 7 shows a cross section of the coupling means including a one-way transmission means according to Figure 6, represented in the condition of interruption of the motion transmission.

Figure 8 shows in its left hand portion a view, and in its right hand portion a cross section, of a coupling means including a one-way transmission means, according to a second embodiment, represented in the condition of motion transmission.

Figure 9 shows in its left hand portion a view, and in its right hand portion a cross section, of the coupling means including a one-way transmission means according to Figure 8, represented in the condition of interruption of the motion transmission.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The pump according to this invention is particularly suitable for use as a vacuum pump for automotive application, and the following description refers to said application, but it is to be understood that this application is not exclusive, and that the features according to the invention can be used in several other applications of displacement pumps, some of them having already been mentioned as examples.

With reference to Figure 1 , which represents in an entirely diagrammatic manner the principle on which the invention is based, reference P designates a rotary displacement pump, as in particular a vacuum pump for auto- motive use, which, according to the invention, should have the possibility of being operated either by a transmission T coming from a first energy source, as in particular a thermal traction engine, or by a second energy source E, as in particular an own electric motor. To this purpose, the ends of rotor R of the pump P (which in this Figure are represented as protruding from the body of pump P) are connected to coupling means M1 and M2, intended to transmit the motion to rotor R from the transmission T and respectively from the electric motor E. Between rotor R and at least the coupling means M1 connected to the transmission T there is inserted a one-way transmission means or freewheel L. As a consequence of these arrangements, when the first energy source (a thermal traction engine) operates the transmission T in the rotation direction that is preestablished for the operation of pump P, to which corresponds the transmission condition of the one-way transmission means L, the coupling means M1 and the one-way transmission means L transfer the operation to rotor R and therefore to pump P. When, for whatever reason, the first energy source operates the transrrvission T in the direction opposite to the direction preestablished for operating the pump P.lhe one-way transmission means L prevents the operation being transferred to rotor R and to pump P. This latter, therefore, is protected against any counterrotation.

On its turn, the second energy source (the electric motor E), when operated, transmits the operation through the coupling means M2 to rotor R and to pump P, no matter whether the first energy source is inactive or it is active with insufficient speed. Therefore, the second energy source E is able to pro- vide for a correct operation of pump P when the first energy source is not able to do so. Thanks to the presence of the one-way transmission means L, the operation transmitted to pump P by the second energy source has no influence on the condition of the first energy source, and in particular the second energy source does not aim to transmit the motion to the first energy source, nor it can be braked by the same.

In the case represented, wherein no one-way transmission means is associated with the coupling means M2, the electric motor E is driven in permanent manner when the operation of the pump P comes, through the transmission T, from the thermal traction engine. In this case, the electric motor E can be freely driven without disadvantages in view of the low resistance opposed by a freely rotating electric motor. Otherwise, the thus driven electric motor E can be exploited as an electric generator, in order to contribute to the charge of the batteries.

As an alternative, a one-way transmission means (not represented in Figure 1 ) can be associated to the coupling means M2 too. In this case, each one of the two energy sources can operate the pump in a way entirely independent from the other energy source.

With reference to Figure 2, there is represented the whole comprising a pump P, a transmission T coming from a thermal traction engine, and a driving electric motor E.« Two cross sections, taken respectively along lines Ill-Ill and IV-IV of Figure 1 , are represented respectively in Figure 3 and in Figure 4, and in Figure 5 there is represented the cross section of a modified embodiment, taken along a line parallel to line IV-IV and symmetric to line Ill-Ill with respect to the body of pump P. The internal structure of pump P is not represented, because it may be the structure of any rotary displacement pump, and it has no influence on the application of this invention.

As it may be observed from Figure 3, to the coupling means 1 , which may be a simple key connected to the transmission T, is associated a one-way transmission means designated in general with 2, which can be housed in a cavity of rotor 3 of the pump P. The one-way transmission means 2 forms a so-called freewheel, and it is so arranged as to transmit the motion from the transmission T to rotor 3 of the pump P only when the transmission T rotates in the direction corresponding to the rotation direction preestablished for operation of the pump P. On the other hand, as it may be observed from Figure 4, the coupling means 4, which also may be a key, connects in a permanent manner the rotor 3 of pump P to the electric motor E; to this coupling means there is associated no one-way transmission means, which in this transmission is not needed. In this case, when pump P is operated by the transmission T, also the electric motor E is driven.

However, as a modification represented in Figure 5, also to the coupling means 4 can be associated a one-way transmission means designated in general as 5, so arranged as to transmit the motion from the electric motor E to rotor 3 of the pump P only when the electric motor E rotates in the direction corresponding to the rotation direction preestablished for operation of the pump P. In this case, when the pump P is operated by the transmission T, the electric motor E is not driven.

The one-way transmission means 2, not shown in detail in Figure 3 (and to which is completely similar the one-way transmission means 5 of Fig- ure 5), is represented in an axial view in Figure 6, in its condition of transmission, and is represented in cross section in Figure 7, in its condition of non- trasmission.

In this embodiment, the one-way transmission means has a positive transmission, and it includes a cavity 6 formed in rotor 3 of the pump, this cavity having one or more (in this case two) asymmetric peripheral recesses 7. A corresponding number (in this case two) of flaps 8 are housed in said cavity 6 of rotor 3, and they are articulated at 9 to the coupling means 1. These flaps 8 are pushed outwards by springs 10 and are arranged in such a way that they engage said recesses 7 when the coupling means 1 rotates in the di- rection preestablished for the operation of the pump, thus establishing a positive motion transmission towards rotor 3. This transmission condition is represented in Figure 6.

When, on the contrary, the coupling means T rotates in a direction opposite the direction preestablished for operation of the pump, the flaps 6 are retracted inwards, against the action of springs 10, thus interrupting the motion transmission. This condition of non-transmission is represented in Figure 7. Figures 8 and 9 represent another embodiment of the one-way transmission means, which in this case has a frictional transmission. In both Figures, the device is represented in an axial view in the left hand portion of the Figure, and in a cross section in the right hand portion of the Figure. This one-way transmission means comprises a cylindrical cavity 11 formed in the rotor 3 and a member 12 connected to the coupling means 1. Member 12 has peripheral lanes 13 shaped as spiral sectors, wherein are housed roll elements 14 arranged in such a way that they wedge between said lanes 13 and the wall of the cylindrical cavity 11 when the coupling means 1 rotates in the direction preestablished for operation of the pump, thus establishing a motion transmission towards rotor 3. This transmission condition is represented in Figure 8.

When, on the contrary, the coupling means 1 rotates in a direction opposite the direction preestablished for operation of the pump, the roll elements 14 cease wedging and thus they interrupt the motion transmission. This condition of non-transmission is represented in Figure 9.

With this arrangement, the one-way transmission means can be designed for a limited torque, by arranging and sizing the component parts in such a way that the frictional motion transmission gives rise to a sliding in the presence of an excessive driving torque, thus protecting the pump against possible overcharges.

Although two possible embodiments of the one-way transmission means have been described and shown, it is to be understood that these examples are in no way limitative, and that any suitable freewheel device may be used according to the invention. It should be understood that this invention is not limited to the embodiments described and shown as examples Several possible modifications have been pointed out in the course of the description, and others are within the ability of those skilled in the art These modification and others, and any replacement by technically equivalent means, can be made to what has been described and shown, without departing from the spirit of the invention and the scope of this Patent as defined by the appended Claims

Claims

1 . A rotary displacement pump (P) including a rotor (3), characterized in that said rotor (3) is provided at both its ends with coupling means (M1.M2; 1 ,4) in order to be driven by two different energy sources (T, E), and in that at least one of said coupling means (M1 .M2; 1 ,4) includes a one-way transmission means (L; 2,5), namely a so-called_*freewheel.

2 . A displacement pump according to Claim 1 , characterized in that said one-way transmission means (L; 2) is associated to only one (M1 ; 1) of the coupling means of the rotor (R; 3).

3 . A displacement pump according to Claim 2, characterized in that a thermal traction engine (T) of a vehicle is coupled to the rotor (R; 3) of the pump (P) through said one-way transmission means (M1 ; 1 ).

4 . A displacement pump (P) according to Claim 2, characterized in that a driving electric motor (E) is coupled to the rotor (R; 3) of the pump (P) in a permanent manner.

5 . A displacement pump (P) according to Claim 4, characterized in that said electric motor (E) can be used, when needed, as an electric generator, in order to contribute to the charge of the batteries.

6 . A displacement pump (P) according to Claim 1 , characterized in that a one-way transmission means (L; 2,5) is associated with each of the two coupling means (M1 ,M2; 1 ,2) of the rotor (R; 3).

7 . A displacement pump (P) according to Claim 6, characterized in that a thermal traction engine (T) of a vehicle is coupled to the rotor (R; 3) of the pump (P) through one (L; 2) of said one-way transmission means.

8 . A displacement pump (P) according to Claim 6, characterized in that a driving electric motor (E) is coupled to the rotor (R; 3) of the pump (P) through one (5) of said one-way transmission means.

9 . A displacement pump (P) according to Claim 1 , characterized in that said one-way transmission means (L; 2,5) is a positive transmission means.

10 . A displacement pump (P) according to Claim 9, characterized in that said one-way transmission means (L; 2,5) comprises a cavity of rotor (R; 3) having one or more peripheral recesses (7), and a corresponding number of flaps (8) housed in said cavity of rotor (R; 3), articulated to the coupling means (M1.M2; 1 ,2), pushed outwards by springs (10) and so arranged as to engage said recesses (7) when the coupling means rotates in the preestablished direction for operation of the pump (P), tfius establishing a motion transmission towards the rotor (R; 3), and as to retract inwards, -thus breaking off the motion transmission, when the coupling means rotates in the direction opposite the rotation direction preestablished for the operation of the pump (P).

11 . A displacement pump (P) according to Claim 1 , characterized in that said one-way transmission means (L; 2,5) is a frictional transmission means.

12 . A displacement pump (P) according to Claim 11 , characterized in that said one-way transmission means (L; 2,5) comprises a cylindrical cavity

(11 ) of the rotor (R; 3) and a member (12), connected to the coupling means (M1 ,M2; 1 ,2), having peripheral lanes (13) shaped as spiral sectors, wherein are housed roll elements (14) arranged for wedging between said lanes (13) and the wall of said cylindrical cavity (11 ) when the coupling member rotates in the direction preestablished for the operation of the pump (P), thus establishing a motion transmission towards the rotor (R; 3), and for ceasing said wedging and breaking off the motion transmission when the coupling member rotates in the direction opposite to the direction preestablished for the operation of the pump (P).

13 . A displacement pump (P) according to Claim 11 , characterized in that said one-way transmission means (L; 2,5) is subject to a torque limitation, the component parts thereof being arranged and sized in such a manner that the motion transmission gives rise to a sliding when the driving torque is excessive, in order to protect the pump (P) against possible overcharges.

14 . A displacement pump (P) according to one or more of the foregoing Claims^', characterized by its application for pumping air or gases.

15 . A displacement pump (P) according to Claim 14, characterized by its application as a vacuum pump intended to feed apparatuses or pneumatic implements that require a depression.