Patent Application
20160377077
The present disclosure relates to a pump for motor vehicles. More specifically, the present disclosure relates to a two rotor vane pump.
The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Many modern motor vehicle automatic continuously variable transmissions (CVT) utilize controlled hydraulic fluid (for example, transmission oil) to actuate CVT belt and pulleys (or chain and pulleys) to achieve a desired ratio in downsized turbo boosted engines to optimize fuel economy. The control of such hydraulic fluid is achieved by a valve body that directs hydraulic fluid flow to pulley pistons as well as other clutch and brake actuators. The valve body is supplied with pressurized hydraulic fluid from, typically, a gear or vane pump, which is driven by the engine output shaft or the transmission input shaft.
For example, in some configurations, a fixed displacement pump provides fluid flow proportional to engine speed. The pump is often sized to meet hydraulic pressure and volume demands of the transmission at low speed idle engine conditions. Larger diameter higher displacement pumps that meet hydraulic demands of the transmission near engine idle speed often contribute to undesirable transmission spin losses and decrease efficiency of the transmission. A large pump will provide much greater oil flow than what is consumed by the transmission at higher engine speeds, with higher pump power consumption leading to loss in overall transmission efficiency.
Accordingly, the present invention is directed to a pump that improves transmission efficiency while meeting hydraulic demands of the transmission.
A vane pump includes a first cam ring and a second cam ring, a first rotor positioned in the first cam ring and a second rotor positioned in the second cam ring, and a shaft. The first rotor is engaged with the shaft so that the first rotor rotates relative to the first cam ring about an axis extending through the shaft, and the second rotor selectively engages with the shaft so that the second rotor selectively rotates relative to the second cam ring about the axis. A piston positioned in the shaft translates within the shaft between a first positon and a second position. When in the first position, the shaft engages with the second rotor so that the second rotor rotates relative to the second cam ring about the axis, and when in the second position, the shaft disengages with the second rotor so that the second rotor does not rotate relative to the second cam ring.
Further features, advantages, and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the views. In the drawings:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Referring now to the drawings, a two rotor vane pump embodying the principles of the present invention is illustrated in
The first rotor 21 includes a set of vanes 23. The vanes of the set of vanes 23 are spaced apart and positioned about the outer periphery of the first rotor 21. The second rotor 22 includes a set of vanes 25. The vanes of the set of vanes 25 are spaced apart and positioned about the outer periphery of the second rotor 22. Referring further to
A dog clutch 31 is positioned about the shaft 16. A piston 28 is positioned in a bore 48 of the shaft 16. The piston 28 is coupled to the shaft 16 with a pin 26 that extends through a hole 29 of the piston 28 and diametrically positioned holes 35 of the dog clutch 31. The pin 26 engages with a pair of diametrically positioned slots 50 in the shaft 16. Accordingly, the piston 28 is able to slide translationally back and forth within the bore 48 to the extent that the ends of the pin 26 are able to slide along the slots 50. A spring 24 is positioned in a region 52 between the piston 28 and a face 54. Hence, as the piston 28 slides towards the face 54, the spring 24 is compressed between the piston 28 and the face 54. A passageway 30 extends from the end 40 along the shaft 16 to the region 52. As such, the passageway 30 enables the region 52 to communicate with the exterior of the shaft 30. The end 40 includes a set of teeth 41 that engages with, for example, a chain that is also engaged with an output shaft of an engine or input shaft of a transmission such that rotation of the engine output shaft or the transmission input shaft drives the pump 10.
The dog clutch 31 includes a set of teeth 36 that, depending on the position of the dog clutch 31 relative to the shaft 16, selectively engages with a set of teeth 49 located in the interior region of the cam ring 22. Hence, rotation of the shaft 16 results in the rotation of the second rotor 22 and consequently the rotation of the vanes 25 when the teeth 36 of the dog clutch 31 are engaged with the teeth 49 of the cam ring 22. When the teeth 36 are unengaged from the teeth 49, the shaft 16 is unengaged from the second rotor 22 such that rotation of the shaft 16 does not produce direct rotation of the second rotor 22.
Engagement of the dog clutch 31 with the second rotor 22 is determined by the position of dog clutch 31 relative to the second rotor 22. Specifically, the dog clutch 31 is in a first, or engaged, position when its teeth 36 are engaged with the teeth 49 of the second rotor 22, and the dog clutch 31 is in a second, or unengaged, position when its teeth 36 are unengaged with the teeth 49 of the second rotor 22. Accordingly, when the dog clutch 31, and hence the piston 28 is in the first position, both the first rotor 21 and the second rotor 22 rotate along with the rotation of the shaft 16 so that the two vane rotor pump 10 operates, for example, as a high pressure pump. And when the dog clutch 31, and hence the piston 28 is in the second position, only the first rotor 21 rotates along with the rotation of the shaft 16 so that the two vane rotor pump 10 operates, for example, as a low pressure pump. Note that a synchronizer can be employed in place of the dog clutch 31.
Turning now to
Referring now to
When the hydraulic circuit 100 is in use, the prime mover 106 rotates the first rotor 21 of the first component 10a at a desired speed so that the pump 10 supplies low pressure hydraulic fluid from the reservoir or sump 110 through the transmission controller 108 to the clutch pack 104. When high pressure hydraulic fluid is desired to operate, for example, the CVT pulley 102, the transmission controller 108 transmits a signal along a line 114 to the synchronizer 112 to couple the two components 10a and 10b together so that the second rotor 22 rotates along with the first rotor 21. Accordingly, additional hydraulic fluid is pumped from the component 10b through a check valve 107 so that the components 10a and 10b operate together as a high pressure pump for supplying high pressure hydraulic fluid to the CVT pulley 102. If the pressure in the circuit 100 rises to a predetermined maximum pressure, the pressure relief valve 116 releases enough hydraulic fluid to prevent over-pressurization the circuit 100.
The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
