Oil pump

• US 20050106044A1
• Filed: 11/10/2004
• Published: 05/19/2005
• Est. Priority Date: 11/17/2003
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Watanabe, Yasushi, Ohnishi, Hideaki, Morita, Shoji
• Granted Patent: US 7,704,061 B2
• Time in Patent Office: Days
• US Class Current: 417/410.400
• CPC Class Codes: F04C 15/0049 Equalization of pressure pulses silencing for compressors F04C29/06
• CPC Class Codes: F04C 2/086 Carter
• CPC Class Codes: F04C 2/102 the two members rotating simultaneously around their respective axes
• CPC Class Codes: F04C 2250/102 of the outlet

Abstract

An oil pump includes pump chambers each having a volume varied by engine drive and for pressurizing oil inhaled through an inlet port and discharge it through an outlet port, and a branch passage connected between upstream and downstream sides of the outlet port at branch and confluent points, wherein the branch passage in the vicinity of the confluent point is shifted in pulse-pressure phase with respect to the outlet port.

Claims

1. An oil pump, comprising:

a plurality of pump chambers each having a volume varied by engine drive, the pump chambers pressurizing oil inhaled through an inlet port and discharge it through an outlet port; and

a branch passage connected between upstream and downstream sides of the outlet port at branch and confluent points, the branch passage in a vicinity of the confluent point being shifted in pulse-pressure phase with respect to the outlet port.

2. The oil pump as claimed in claim 1, wherein a flow rate of oil flowing through the outlet port and that of oil flowing through the branch passage are substantially the same between the branch and confluent points.

3. The oil pump as claimed in claim 1, further comprising a balancer shaft which drives the oil pump, the balancer shaft rotating at speed twice as high as a crankshaft to cancel engine secondary vibrations.

4. The oil pump as claimed in claim 1, further comprising:

a drive shaft;

an inner rotor driven by the drive shaft, the inner rotor having an outer periphery formed with external teeth each including a trochoid curve; and

an outer rotor disposed at the inner periphery of the inner rotor, the outer rotor being offset with respect to the inner rotor, the outer rotor having an inner periphery formed with internal teeth each including the trochoid curve, the internal teeth being meshed with the external teeth of the inner rotor.

5. The oil pump as claimed in claim 1, further comprising a pump housing, the pump housing comprising a base block and a cover block attached to a front face of the base block,

wherein the outlet port and branch passage are formed in half at a junction between the base block and the cover block,

wherein the base block and the cover block are coupled together by a plurality of bolts.

6. The oil pump as claimed in claim 1, wherein the branch passage extends curvedly with respect to the outlet port which extends linearly.

7. An oil pump, comprising:

a plurality of pump chambers each having a volume varied by engine drive, the pump chambers pressurizing oil inhaled through an inlet port and discharge it through an outlet port; and

a branch passage connected between upstream and downstream sides of the outlet port at branch and confluent points,

the outlet port and the branch passage having different distances between the branch point and the confluent point.

8. The oil pump as claimed in claim 7, wherein a flow rate of oil flowing through the outlet port and that of oil flowing through the branch passage are substantially the same between the branch and confluent points.

9. The oil pump as claimed in claim 7, further comprising a balancer shaft which drives the oil pump, the balancer shaft rotating at speed twice as high as a crankshaft to cancel engine secondary vibrations.

10. The oil pump as claimed in claim 7, further comprising:

a drive shaft;

an inner rotor driven by the drive shaft, the inner rotor having an outer periphery formed with external teeth each including a trochoid curve; and

an outer rotor disposed at the inner periphery of the inner rotor, the outer rotor being offset with respect to the inner rotor, the outer rotor having an inner periphery formed with internal teeth each including the trochoid curve, the internal teeth being meshed with the external teeth of the inner rotor.

11. The oil pump as claimed in claim 7, further comprising a pump housing, the pump housing comprising a base block and a cover block attached to a front face of the base block,

wherein the outlet port and branch passage are formed in half at a junction between the base block and the cover block,

wherein the base block and the cover block are coupled together by a plurality of bolts.

12. The oil pump as claimed in claim 7, wherein the branch passage extends curvedly with respect to the outlet port which extends linearly.

13. An oil pump, comprising:

a plurality of pump chambers each having a volume varied by engine drive, the pump chambers pressurizing oil inhaled through an inlet port and discharge it through an outlet port;

a branch passage connected between upstream and downstream sides of the outlet port at branch and confluent points; and

a throttle provided to the branch passage at at least one of the branch and confluent points, the throttle being smaller in cross-sectional area than a general section of the branch passage.

14. The oil pump as claimed in claim 13, wherein a flow rate of oil flowing through the outlet port and that of oil flowing through the branch passage are substantially the same between the branch and confluent points.

15. The oil pump as claimed in claim 13, further comprising a balancer shaft which drives the oil pump, the balancer shaft rotating at speed twice as high as a crankshaft to cancel engine secondary vibrations.

16. The oil pump as claimed in claim 13, further comprising:

a drive shaft;

an inner rotor driven by the drive shaft, the inner rotor having an outer periphery formed with external teeth each including a trochoid curve; and

an outer rotor disposed at the inner periphery of the inner rotor, the outer rotor being offset with respect to the inner rotor, the outer rotor having an inner periphery formed with internal teeth each including the trochoid curve, the internal teeth being meshed with the external teeth of the inner rotor.

17. The oil pump as claimed in claim 13, further comprising a pump housing, the pump housing comprising a base block and a cover block attached to a front face of the base block,

wherein the outlet port and branch passage are formed in half at a junction between the base block and the cover block,

wherein the base block and the cover block are coupled together by a plurality of bolts.

18. The oil pump as claimed in claim 13, wherein the branch passage extends curvedly with respect to the outlet port which extends linearly.

19. The oil pump as claimed in claim 13, further comprising another throttle provided to the branch passage at another of the branch and confluent points.

20. The oil pump as claimed in claim 13, wherein the throttle serves to attenuate a pulse pressure within the outlet port.