Field of the invention

This invention relates to a balanced variable vane pump.

This invention relates to a method of position determination and wear determination of a balanced variable vane pump.

Background of the invention

Variable vane pumps are widely used in a number of industries such as automotive, aerospace and the like. A variable vane pump is a pump wherein the flow rate of the pump can be varied as per the end requirement of the application in which it is used. Variable vane pumps known in the state of the art comprise at least a rotor on which are mounted pluralities of vanes. The rotor may be eccentrically located in the compression chamber and encompassed by the stator. As the rotor rotates eccentrically in the stator the fluid that is sucked into the compression chamber is pressurized due to the compression of the vanes along the walls of the stator. The variable flow to the pressurized fluid is imparted by means of CAM-ring which is mounted at the input and output side of the variable vane pump. The CAM-ring is provided with a number of input and output lobes which helps in introducing the fluid into the compression chamber and pumping the fluid out of the pump. A balanced variable vane pump is a variable vane pump with even number of lobes on the CAM-ring. The even number of lobes helps to balance the forces on the bearing of the variable vane pump. The CAM-ring is rotated by a variety of linear or rotary means, one such variable displacement vane pump with a rotating CAM-ring is known from the patent document numbered EP1384005.

Balanced variable vane pumps today are controlled via electronic means. Further, for accurate control there is a need that the position of the CAM-ring is known. One method to determine the position of CAM-ring known in the state of art disclosed in US7575420. The balanced variable vane pump disclosed comprises at least two locating ring which are used to determine the position of the CAM-ring.

It is also important there is possibility of evaluating the life of the balanced variable vane pump. The remaining useful life of the balanced variable vane pump can be determined based on the amount ot wear that the various components of the balanced variable vane pump have undergone. The amount of wear can be measurable in terms of the amount of fluid that is output for a given back pressure from the balanced variable vane pump. This method of wear determination to determine the useful life of the balanced variable vane pump is a method which can be used only when there already existent leakage in the balanced variable pump. One such method of wear determination of the balanced variable vane pump is disclosed in EP1531270. The wear determination method discloses the use of components known as undervanes which are located in proximity of the vanes of the balanced variable vane pump. When the vanes are within wear limits, the leakage through the undervanes is minimal. However, as the vanes wear out, the leakage increases. The increase in leakage is checked against an allowable value of leakage, if the leakage is within a threshold leakage value then the balanced variable vane pump is determined useable else it is determined that the useful life of the balanced variable vane pump is over. However, failure of the balanced variable vane pump due to failure of any other component cannot be determined using this method.

It is object of this invention to provide a method of determination of position of the CAM-ring of the balanced variable vane pump and a method determination of useful life of the balanced variable vane pump based on the position of the CAM-ring.

In accordance with this invention we will focus on the mechanism used to determine position of the CAM-ring and also determine remaining useful life or wear of the CAM-ring of the balanced variable vane pump.

Brief description of the accompanying drawings

Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

Figure 1 illustrates balanced variable vane pump in accordance with this invention; Figure 2 illustrates a first embodiment of the balanced variable vane pump with the electronic control unit; and

Figure 3 illustrates a second embodiment of the balanced variable vane pump with the electronic control unit.

Detailed description of the invention

Figure 1 illustrates a first embodiment of the balanced variable vane pump 10 in accordance with this invention. The balanced variable vane pump 10 comprises a CAM-ring 12 and a drive mechanism 14. The drive mechanism 14 is adapted to engage at least a part of the CAM-ring 12. The balanced variable vane pump 10 is characterized by a sensor 16 located in proximity of the CAM-ring 12 and the drive mechanism 14. The sensor 16 is adapted to determine position of the CAM-ring 12. As seen in figure 2 and figure 3, a motor driver 18 is adapted to drive the drive mechanism 14. The operation of the motor driver 18 is controlled by the electronic control unit 20. The electronic control unit 20 is further connected to the sensor 16. The electronic control unit 20 is adapted to receive signal from the sensor 16 in the balanced variable vane pump 10 to determine position of the CAM-ring 12 of the balanced variable vane pump 10. The electronic control unit 20 also determines wear of the balanced variable vane pump 10 on receiving system signal from the system 22 in which the balanced variable vane pump 10 and the sensor signal from the sensor 16.

The detailed construction of the balanced variable vane pump 10 in accordance with this invention can be easily understood by knowing the detailed construction of the components of the balanced variable vane pump 10. The CAM-ring 12 is provided with pluralities of teeth 24 on at least a part of the outer circumference of the CAM-ring 12. With reference to the CAM-ring, the sensor 16 is located in proximity of the pluralities of teeth 24 of the CAM-ring 12. The drive mechanism 14 is adapted to engage at a part of the pluralities of teeth 24 on the outer circumference of CAM-ring 12 to impart movement to CAM-ring 12. The drive mechanism 14 which imparts movement to the CAM-ring 12 comprises a gear assembly 26 and a drive 28. The gear assembly 26 engages at least a part of the pluralities of teeth 24 on at least a part of the outer circumference of the CAM-ring 12. The drive 28 is adapted to impart motion to the gear assembly 26. The drive mechanism 14 is actuated by the motor driver 18. When the drive 28 of the drive mechanism 14 is actuated by the motor driver 18 the gear assembly 26 imparts movement to the CAM-ring 12 allowing flow from the output of the balanced variable vane pump 12 to vary. As mentioned earlier the sensor 16 is located in proximity of the CAM-ring 12 and in proximity of the drive mechanism 14 of the balanced variable vane pump 10. In accordance with the first embodiment of the balanced variable vane pump as seen in figure 2, the sensor is located in proximity of the pluralities of teeth 24 of the CAM-ring 12. In accordance with the second embodiment of the balanced variable vane pump 10 as seen in figure 3, the sensor is located in proximity of the gear assembly 26 which engages the teeth 24 on a part of the outer circumference of the CAM-ring 12.

The sensor 16 may be a contact type sensor or a non-contact type sensor. The contact type sensor may be selected from a group of contact sensors 16 such as resistive type contact sensor, encoder type contact sensor and the like. In accordance with a first embodiment of the balanced variable vane pump 10, the contact type sensor 16 will be in contact with the pluralities of teeth 24 of the CAM-ring 12. In accordance with a second embodiment of the balanced variable vane pump 10, the contact type sensor 16 will be in contact with the gear assembly 26 of the drive mechanism 14 of the balanced variable vane pump 10. One example of the use of contact type sensor is the use of a resistive type contact sensor 16, which works on the same principle of a potentiometer/rheostat. With reference to the first embodiment of the balanced variable vane pump 10 mentioned above, at least one tooth of the pluralities of teeth 24 of the CAM-ring 12, is in contact with the resistive type contact sensor 16. With reference to the second embodiment of the balanced variable vane pump 10 mentioned above, at least some part of the gear assembly 26 will be in contact with the resistive type contact sensor 16.

The working of this type of resistive type contact sensor 16 in either of the two above mentioned embodiments is the same and can be explained as follows. The electronic control unit 20 receives a system signal from a system 22 in which the balanced variable vane pump 10 is used. The system signal requires that the output flow of the balanced variable vane pump 10 to be varied. For varying the output flow, the electronic control unit 20, actuates the motor drive 18. The motor drive 18 in turn drives the drive 28 of the drive mechanism 14 of the balanced variable vane pump 10. When the drive 28 is driven by the motor driver 18, the gear assembly 26 which is in contact with the pluralities of teeth 24 on the CAM-ring 12, imparts movement to the CAM-ring 12. When the CAM-ring 12 moves the output flow of the balanced variable vane pump 10 is changed. As mentioned in the previous paragraph at least one of the pluralities of teeth 24 of the CAM-ring 12 are in contact with the sensor 16. Thus when movement is imparted to the CAM-ring 12, the resistance of the resistive type contact sensor 16 which is in contact with the CAM-ring 12 varies. In dependence of the changing resistance the voltage changes, this voltage signal is sent back to the electronic control unit 20. Based on the signal received from the sensor 16, the electronic control unit determines the position of the CAM-ring 12. The position of the CAM-ring 12 is indicative of the output flow of the balanced variable vane pump 10.

In accordance with the second embodiment where the resistive type contact sensor 16 is in contact with the gear assembly 26. When the gear assembly 26 which is in contact with the pluralities of teeth 24 of the CAM-ring 12 moves, the resistance of the resistive sensor 16 changes. This change in resistance causes the voltage to change. This voltage signal is sent back to the electronic control unit 20. Based on the signal received from the sensor 16, the electronic control unit 20 determines the position of the CAM-ring 12. The position of the CAM-ring 12 is indicative of the output flow of the balanced variable vane pump 10.

Either in case of the first or the second embodiment mentioned above, the position of the CAM-ring 12 is determined by the electronic control unit 20. Once the position of the CAM-ring 12 is determined the output flow of the balanced variable vane pump 10 using the system signal. This system signal regarding output flow of the balanced variable vane pump 10 is sent to the electronic control unit 20. The output flow value of the balanced variable vane pump 10 is compared with a threshold of the output flow value for that particular position of the CAM-ring 12. If the output flow value is beyond the threshold value, then it is determined that the CAM-ring has some wear damage. An indication that the CAM-ring 12 is worn out can be provided by the electronic control unit 20.

As mentioned earlier the sensor 16 may be a non-contact type of sensor 16. The non-contact type of sensor may be selected from a group of non-contact type of sensor such as Hall effect sensors, Inductive sensors, Magnetic sensors, Optical sensors and the like.

In accordance with another embodiment of the sensor 16 in the balanced variable vane pump 10 of this invention, a non-contact type optical sensor 16 is used. The non-contact type optical sensor 16 is located in proximity of the pluralities of teeth 24 of the CAM-ring 12 as shown in figure 2. The non-contact type optical sensor 16 would send an optical signal toward the pluralities of the teeth 24 of the CAM-ring 12 and receive a signal, which is then sent to the electronic control unit 20. Based on the received signal, the electronic control unit 20 is adapted to determine the position of the CAM-ring 12 of the balanced variable vane pump. Once the position of the CAM-ring 12 is determined the output flow of the balanced variable vane pump 10 using the system signal. This system signal from the system 22 regarding output flow of the balanced variable vane pump 10 is sent to the electronic control unit 20. The output flow value of the balanced variable vane pump 10 is compared with a threshold of the output flow value for that particular position of the CAM-ring 12. If the output flow value is beyond the threshold value, then it is determined that the CAM-ring has some wear damage. An indication that the CAM-ring 12 is worn out can be provided by the electronic control unit 20.

The non-contact type optical sensor 16 is located in proximity of the gear assembly 26 of the drive mechanism 14, as shown in figure 3. The non-contact type optical sensor 16 would send an optical signal toward the pluralities of the gear assembly 26 of the drive mechanism 14 and receive a signal, which is then sent to the electronic control unit 20. Based on the received signal, the electronic control unit 20 is adapted to determine the position of the CAM-ring 12 of the balanced variable vane pump. Once the position of the CAM-ring 12 is determined the output flow of the balanced variable vane pump 10 using the system signal. This system signal from the system 22 regarding output flow of the balanced variable vane pump 10 is sent to the electronic control unit 20. The output flow value of the balanced variable vane pump 10 is compared with a threshold of the output flow value for that particular position of the CAM-ring 12. If the output flow value is beyond the threshold value, then it is determined that the CAM-ring has some wear damage. An indication that the CAM-ring 12 is worn out can be provided by the electronic control unit 20. sensor such as Hall effect sensors, Inductive sensors, Magnetic sensors, Optical sensors and the like.

In accordance with another embodiment of the sensor 16 in the balanced variable vane pump 10 of this invention, a non-contact type optical sensor 16 is used. The non-contact type optical sensor 16 is located in proximity of the pluralities of teeth 24 of the CAM-ring 12 as shown in figure 2. The non-contact type optical sensor 16 would send an optical signal toward the pluralities of the teeth 24 of the CAM-ring 12 and receive a signal, which is then sent to the electronic control unit 20. Based on the received signal, the electronic control unit 20 is adapted to determine the position of the CAM-ring 12 of the balanced variable vane pump. Once the position of the CAM-ring 12 is determined the output flow of the balanced variable vane pump 10 using the system signal. This system signal from the system 22 regarding output flow of the balanced variable vane pump 10 is sent to the electronic control unit 20. The output flow value of the balanced variable vane pump 10 is compared with a threshold of the output flow value for that particular position of the CAM-ring 12. If the output flow value is beyond the threshold value, then it is determined that the CAM-ring has some wear damage. An indication that the CAM-ring 12 is worn out can be provided by the electronic control unit 20.

The non-contact type optical sensor 16 is located in proximity of the gear assembly 26 of the drive mechanism 14, as shown in figure 3. The non-contact type optical sensor 16 would send an optical signal toward the pluralities of the gear assembly 26 of the drive mechanism 14 and receive a signal, which is then sent to the electronic control unit 20. Based on the received signal, the electronic control unit 20 is adapted to determine the position of the CAM-ring 12 of the balanced variable vane pump. Once the position of the CAM-ring 12 is determined the output flow of the balanced variable vane pump 10 using the system signal. This system signal from the system 22 regarding output flow of the balanced variable vane pump 10 is sent to the electronic control unit 20. The output flow value of the balanced variable vane pump 10 is compared with a threshold of the output flow value for that particular position of the CAM-ring 12. If the output flow value is beyond the threshold value, then it is determined that the CAM-ring has some wear damage. An indication that the CAM-ring 12 is worn out can be provided by the electronic control unit 20.

It must be understood that the embodiments of the balanced variable vane pump and the embodiments of the contact and non-contact type sensor 16 as explained above are only illustrative and do not limit the scope of the invention in terms of the types of sensors that can be used to determine position and wear of the balanced variable vane pump operate. Many modifications to the embodiments explained above are envisioned and lie within the scope of this invention.

We Claim:

1. A balanced variable vane pump (10) comprising a CAM-ring (12) and a drive mechanism (14), said drive mechanism (14) adapted to engage at least a part of said CAM-ring (12), Characterized in that a sensor (16) located in proximity of said CAM-ring (12) and said drive mechanism (14) adapted to determine position of said CAM-ring (12).

2. The balanced variable vane pump (10) as claimed in claim 1, wherein said sensor (16) is at least one chosen from a group of sensors such as contact type sensors or non-contact type sensors.

3. The balanced variable vane pump (10) as claimed in claim 1 and 2, wherein said CAM-ring (12) has pluralities of teeth (24) on at least a part of the outer circumference of said CAM-ring (12), said non-contact type sensor (16) is located in proximity of said pluralities of teeth (24) of said CAM-ring (12).

4. The balanced variable vane pump (10) as claimed in claim 1 and 2, wherein said non-contact type sensor (16) is located in proximity of said drive mechanism (14).

5. The balanced variable vane pump (10) as claimed in claim 1 and 2, wherein said contact type sensor (16) is in contact with said pluralities of teeth (24) of said CAM-ring (12).

6. The balanced variable vane pump (10) as claimed in claim 1, wherein said contact type sensor (16) is in contact with said drive mechanism (14).

7. An electronic control unit (20) adapted to determine position and determine wear of a balanced variable vane pump (10), said electronic control unit (20),

- receiving a system signal from a system (22) in which said balanced variable vane pump (10) is used;

- receiving a sensor signal from a sensor (16) in said balanced variable vane pump (10);

- -determining position of a CAM-ring (12) in said balanced variable vane pump (10) in
dependence of said received sensor signal; and

- determining wear of said balanced variable vane pump (10) in dependence of said
received system signal and said received sensor signal.

8. A method of determining position of a CAM-ring in a balanced variable vane pump comprising the following steps:

- actuating movement of a CAM-ring by actuating a drive mechanism (14) using a motor driver 19;

- sensing movement of said CAM-ring through a sensor (16) in said balanced variable vane pump;

- transmitting sensed CAM-ring movement information to an electronic control unit (20); and

- determining position of said CAM-ring in dependence of said sensed CAM-ring movement information.

9. A method of determining wear of a balanced variable vane pump comprising the following steps:

determining position of a CAM-ring in dependence a sensor signal sent to an electronic control unit (20);

determining output flow of said balanced variable vane pump (10) in dependence of a system signal sent to said electronic control unit (20);

comparing said determined output flow of said balanced variable vane pump (10) with a threshold value of output flow of said balanced variable vane pump; and

determining wear of said balanced variable vane pump in dependence of said comparison between determined output flow and threshold value of output flow.