Hydraulic pump of automatic transmission

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2006-0123320 filed in the Korean Intellectual Property Office on Dec. 6, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a hydraulic pump of an automatic transmission. More particularly, the present invention relates to a hydraulic pump of an automatic transmission that prevents bubbles generated by churning by draining surplus oil to a portion of the automatic transmission away from rotational elements.

(b) Description of the Related Art

A hydraulic pump is generally mounted between a torque converter and a transmission case. The hydraulic pump supplies oil to a transmission and a shifting unit, and provides lubrication and cooling of the transmission. The oil of the hydraulic pump is supplied to a line pressure control valve, and oil pressure increases until it reaches a predetermined pressure. The oil then returns to the hydraulic pump through a drain port of the line pressure control valve.

Typically, surplus oil is exhausted through a drain hole to a clutch, and then to a lower portion of the transmission. Therefore, the oil is churned by the rotation of the clutch, and accordingly, bubbles are generated in the oil, deteriorating oil quality.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The present invention provides a hydraulic pump of an automatic transmission that prevents generation of bubbles by exhausting surplus oil through a drain hole to a lower portion of the automatic transmission away from rotational elements.

Exemplary embodiments of the present invention provide a hydraulic pump of an automatic transmission, including: a pump housing; a pump cover attached to the pump housing; a bush attached to the pump housing; a rotor mounted between the pump cover and the pump housing; an oil input port between the pump housing and the pump cover; an oil output port between the pump housing and the pump cover; and a drain hydraulic line between the pump housing and the pump cover. The drain hydraulic line is substantially vertical.

The oil input port, the oil output port, and the drain hydraulic line may be disposed on the pump cover. The drain hydraulic line may be connected to an oil reservoir. A sealing member may further be provided between the pump housing and the bush. Surplus oil may remain at a joint between the sealing member and the bush. The drain hydraulic line may be connected to the joint between the sealing member and the bush through a drain hole of the pump housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded assembly view of a hydraulic pump of an automatic transmission according to an exemplary embodiment of the present invention.

FIG. 2 is a perspective view of a pump cover according to an exemplary embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an automatic transmission in which a hydraulic pump according to an exemplary embodiment of the present invention is installed.

FIG. 4 is a partial enlarged view of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

As shown in FIG. 3, a hydraulic pump 100 of an automatic transmission according to an exemplary embodiment of the present invention is disposed between a torque converter 300 and a shifting unit 200. A main shaft 310 is mounted in the automatic transmission. An oil reservoir 250 is provided at a lower portion of the automatic transmission at a place away from rotational elements, such as clutch C.

The torque converter 300 receives torque from an engine (not shown) and transmits the torque to the main shaft 310. The hydraulic pump 100 and the shifting unit 200 are operated by the torque of the main shaft 310.

The shifting unit 200 includes at least one planetary gear set (not shown), a brake B, and a clutch C.

As shown in FIG. 1, the hydraulic pump 100 according to an exemplary embodiment of the present invention includes a pump housing 110, a pump cover 120 bolted to the pump housing 110, a bush 150 press fitted to the pump housing 110, and a rotor 170 mounted between the pump cover 120 and the pump housing 110. The bush 150 reduces frictional force between the rotor 170 and the pump cover 120. The rotor 170 includes an inner rotor 140 and an outer rotor 130 mounted at an exterior of the inner rotor 140. The rotor 170 pressurizes and exhausts oil by rotating with the main shaft 310.

In addition, a sealing member 160 is interposed between the pump housing 110 and the bush 150. The sealing member 160 prevents the oil of the hydraulic pump 100 from leaking out. Surplus oil, i.e. oil that is not supplied to a valve body, remains at the joint of the bush 150 and the sealing member 160.

In addition, as shown in FIG. 2, an oil input port 210, an oil output port 220, a drain hole 230, and a drain hydraulic line 240 are provided on the pump cover 120, on a surface facing the pump housing 110.

In operation, the oil is supplied to the pump 100 from an oil fan (not shown) through the oil input port 210, and exhausted to the valve body (not shown) through the oil output port 220.

The drain hole 230 is connected to the joint of the bush 150 and the sealing member 160. Therefore, the surplus oil remaining at the joint of the bush 150 and the sealing member 160 drains through the drain hole 230. In addition, the drain hole 230 is connected to the drain hydraulic line 240.

The drain hydraulic line 240, as shown in FIG. 3 and FIG. 4, extends downward, substantially vertically, and is connected to the oil reservoir 250.

Therefore, after the surplus oil at the joint of the bush 150 and the sealing member 160 drains through the drain hole 230 through the drain hydraulic line 240, and to the oil reservoir 250, since no rotational elements are provided near the oil reservoir 250, bubbles generated in the oil by churning are avoided.

The oil in the oil reservoir 250 is filtered and supplied to the hydraulic pump 100 through the oil input port 210.

According to the present invention, because surplus oil is drained to an oil reservoir away from rotational elements, churning of the oil, and bubbles in the oil, can be avoided, maintaining oil quality.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.