Hydraulic Gerotor pump for automatic transmission

Patent metadata

Field	Value
Publication number	US-11614158-B2
Application number	US-202016927172-A
Country	US
Kind code	B2
Filing date	Jul 13, 2020
Priority date	Jul 13, 2020
Publication date	Mar 28, 2023
Grant date	Mar 28, 2023

Abstract

A hydraulic gerotor pump for an automatic transmission may comprise a housing and a gear set rotatably disposed within the housing. The gear set may comprise an inner gear and an outer gear having radially opposed intermeshing teeth that together define a plurality of circumferentially disposed variable volume pumping chambers therebetween. The housing may be made of a first aluminum-based material, and the inner gear and the outer gear of the gear set may be made of a second aluminum-based material. The linear coefficient of thermal expansion of the first aluminum-based material may be substantially the same as that of the second aluminum-based material.

First claim

What is claimed is:

1. A hydraulic gerotor pump for an automatic transmission, the pump comprising:
a housing having an inlet and an outlet, and defining a cavity in fluid communication with the inlet and the outlet thereof; and
a gear set rotatably disposed within the cavity of the housing, the gear set comprising an inner gear and an outer gear, the inner gear and the outer gear having radially opposed intermeshing teeth that together define a plurality of circumferentially disposed variable volume pumping chambers therebetween,
wherein the housing is made of a first aluminum-based material,
wherein the inner and outer gears of the gear set are made of a second aluminum-based material,
wherein a linear coefficient of thermal expansion of the first aluminum-based material is substantially the same as that of the second aluminum-based material such that an axial clearance between the gear set and the housing is in a range of 0.03 millimeters to 0.09 millimeters at temperatures in a range of −40° C. to 160° C., and
wherein surfaces of the inner gear and the outer gear are (i) coated with an iron alloy, ceramic, cermet, or diamond-like carbon material and/or (ii) treated by boridinq and/or carburizing.

2. The pump of claim 1 wherein the pump exhibits a volumetric efficiency greater than 80% at temperatures in a range of −40° C. to 160° C.

3. The pump of claim 1 wherein the housing comprises an aluminum alloy comprising at least one alloying element selected from the group consisting of iron (Fe), silicon (Si), copper (Cu), magnesium (Mg), manganese (Mn), or zinc (Zn), and wherein the housing is formed by casting.

4. The pump of claim 1 wherein the inner gear and the outer gear of the gear set comprise an aluminum alloy comprising at least one alloying element selected from the group consisting of iron (Fe), silicon (Si), copper (Cu), magnesium (Mg), manganese (Mn), or zinc (Zn).

5. The pump of claim 4 wherein the aluminum alloy exhibits a linear coefficient of thermal expansion in a range of 21 μm/m-° C. to 24 μm/m-° C. at temperatures in a range of 20° C. to 100° C.

6. The pump of claim 4 wherein the inner gear and the outer gear of the gear set are formed by casting or forging.

7. The pump of claim 4 wherein the inner gear and the outer gear of the gear set comprise an aluminum-matrix composite, wherein a matrix phase of the aluminum-matrix composite comprises the aluminum alloy and a dispersed phase of the aluminum-matrix composite comprises a ceramic, and wherein the dispersed phase comprises AIN, SiC, Al 2 O 3 , C, SiO 2 , B, BN, B 4 C, Si 3 N 4 , TiC, TiO 2 , TiB 2 , graphite, or a combination thereof.

8. The pump of claim 7 wherein the inner gear and the outer gear of the gear set are formed by powder metallurgy.

9. The pump of claim 1 wherein the housing comprises a body and a cover, the cavity is at least partially defined by a back wall and a circular side wall of the body of the housing and by a face wall of the cover of the housing, and wherein the body of the housing is of unitary one-piece construction.

10. The pump of claim 9 wherein the inner gear and the outer gear together define a front face of the gear set that faces toward and opposes the face wall of the cover of the housing, a rear face of the gear set that faces toward and opposes the back wall of the body of the housing, and an outer circumferential surface of the gear set that faces toward and opposes the circular side wall of the body of the housing.

11. The pump of claim 10 wherein the gear set is sized and positioned within the cavity of the housing such that the axial clearance is defined between the front face of the gear set and the face wall of the housing, and wherein the axial clearance is substantially constant at temperatures in a range of −40° C. to 160° C.

12. The pump of claim 11 wherein the axial clearance between the front face of the gear set and the face wall of the housing is in a range of 0.03 mm to 0.09 mm at temperatures in a range of −40° C. to 160° C.

13. The pump of claim 10 wherein the front face, the rear face, or the outer circumferential surface of the gear set is coated with an iron alloy, ceramic, cermet, or diamond-like carbon (DLC) material.

14. The pump of claim 1 wherein the inner gear of the gear set has an outer circumferential surface and the outer gear of the gear set has an inner circumferential surface, and wherein the intermeshing teeth of the gear set are defined by the outer circumferential surface of the inner gear and the inner circumferential surface of the outer gear.

15. The pump of claim 14 wherein the outer circumferential surface of the inner gear or the inner circumferential surface of the outer gear is coated with an iron alloy, ceramic, or cermet.

16. The pump of claim 14 wherein the outer circumferential surface of the inner gear or the inner circumferential surface of the outer gear has been chemically treated by a boriding or carburizing process.

17. A hydraulic system for an automatic transmission, the system comprising:
a hydraulic gerotor pump comprising:
a housing having an inlet and an outlet, and defining a cavity in fluid communication with the inlet and the outlet thereof; and
a gear set rotatably disposed within the cavity of the housing, the gear set comprising an inner gear and an outer gear, the inner gear and the outer gear having radially opposed intermeshing teeth that together define a plurality of circumferentially disposed variable volume pumping chambers therebetween,
wherein the housing is made of a first aluminum-based material and the inner gear and the outer gear of the gear set are made of a second aluminum-based material, and
wherein a linear coefficient of thermal expansion of the first aluminum-based material is substantially the same as that of the second aluminum-based material such that an axial clearance between the gear set and the housing is in a range of 0.03 millimeters to 0.09 millimeters at temperatures in a range of −40° C. to 160° C., and
wherein surfaces of the inner gear and the outer gear are (i) coated with an iron alloy, ceramic, cermet, or diamond-like carbon material and/or (ii) treated by boridinq and/or carburizing; and

an electric motor including a rotor coupled to a drive shaft and a stator surrounding the rotor, the rotor including multiple circumferentially disposed permanent magnets,
wherein the drive shaft of the electric motor is mechanically coupled to the inner gear of the gear set of the hydraulic gerotor pump and is operable to drive rotation of the gear set.

18. The system of claim 17 further comprising:
a hydraulic fluid sump in fluid communication with the inlet of the housing.

19. The system of claim 17 further comprising:
a transmission control system in fluid communication with the outlet of the housing.

20. An automatic transmission comprising:
a hydraulic gerotor pump comprising:
a housing having an inlet and an outlet, and defining a cavity in fluid communication with the inlet and the outlet thereof; and
a gear set rotatably disposed within the cavity of the housing,
wherein the housing is made of a first aluminum-based material and the inner gear and the outer gear of the gear set are made of a second aluminum-based material, and
wherein a linear coefficient of thermal expansion of the first aluminum-based material is substantially the same as that of the second aluminum-based material such that an axial clearance between the gear set and the housing is in a range of 0.03 millimeters t

Assignees

• Gm Global Tech Operations Llc

Inventors

• Parrish Robert
• Yang Wenying
• Li Zhe
• Das Abir R
• Huls Chad M
• Sachdev Anil K

Classifications

• F05C2201/903

  Aluminium alloy, e.g. AlCuMgPb F34,37 · CPC title

• F16H57/0436 Primary

  Pumps · CPC title

• F16H57/0435 Primary

  Pressure control for supplying lubricant; Circuits or valves therefor · CPC title

• F04C2/084

  Toothed wheels · CPC title

• F05C2251/044

  similar · CPC title