Pressure accumulator arrangement

Abstract

Pressure accumulator (10) which includes: a housing (12) with a closed end (16) and an open end (18), wherein the housing (12) has an inner surface (22) defining a cavity (20) and a stop (28) arranged in the cavity (20); an end cap (14) arranged above the open end (18) of the housing (12), the end cap (14) having an inlet and an outlet (54) which are connected to the cavity (20) to transfer a hydraulic fluid into and out of the cavity (20); a piston (30) which is arranged in the housing (12) between the stop (28) and the end cap (14), wherein the piston (30) is sealed at the inner surface (22) and is displaceable along an axis; and a preloading element (40) arranged in the housing (12) and located axially between the closed end (16) of the pressure vessel (12) and the piston (30), wherein the preloading element (40) is designed to preload the piston (30) towards the open end (18); and a support element (70) coupled to an outer surface (72) of the closed end (16) of the housing (12), wherein the piston stop (28) is arranged radially outside the preloading element (40) and wherein the support element (70) is at least partially aligned with a section of the preloading element (40) where the preloading element (40) contacts the inner surface (22) of the closed end (16) of the housing (12).

Description

REFERENCE TO RELATED REGISTRATIONS

[0001] This application claims priority over preliminary US application No. 61 / 314,531, filed on March 16, 2010. The disclosure content of the above application is incorporated herein by reference. AREA

[0002] The present disclosure relates to a pressure storage arrangement and in particular to a gearbox pressure storage arrangement with structural support and housing features to maximize manufacturing flexibility. BACKGROUND

[0003] The statements in this section merely provide background information regarding the present disclosure and may, but do not necessarily, represent the state of the art.

[0004] A typical automatic transmission includes a hydraulic control system used to lubricate, cool, and control various transmission components. A pump circulates pressurized hydraulic fluid throughout the transmission. The pump is generally driven by the vehicle's engine. During stop-and-go traffic, it is desirable to turn off the engine to maximize fuel economy. However, turning off the engine also turns off the pump. To pre-charge control devices within the transmission, such as clutches and brakes, a pressure accumulator in the hydraulic control system can be used to supply pressurized hydraulic fluid to these devices, allowing them to engage or operate quickly without waiting for the pump to reactivate.Current pressure accumulator designs are manufactured from cast aluminum parts to provide sufficient strength. While these designs are well-suited for their intended purpose, there is a need in the field for a pressure accumulator arrangement that offers maximum manufacturing flexibility without compromising the accumulator's performance characteristics.

[0005] From DE 100 16 895 B4, a pressure accumulator is known that comprises a housing with a closed end and an open end, an end cap arranged over the open end of the housing, a piston arranged in the housing between the stop and the end cap, and a preloading element arranged in the housing and located axially between the closed end of the housing and the piston. The housing has an inner surface defining a cavity and a stop arranged in the cavity. The end cap has an inlet and an outlet that communicate with the cavity to transfer a hydraulic fluid into and out of the cavity. The piston is sealed against the inner surface of the housing and is displaceable along an axis.Furthermore, the preloading element is designed to preload the piston towards the open end, and the piston stop is arranged radially outside the preloading element.

[0006] A similar pressure accumulator is described in DE 103 30 866 A1.

[0007] DE 101 26 442 C1 describes a pressure accumulator with a support element that is coupled to an outer surface of a closed end of a housing of the pressure accumulator.

[0008] One objective of the invention is to create a pressure accumulator that offers maximum manufacturing flexibility while simultaneously providing increased stability. SUMMARY

[0009] This problem is solved by a pressure accumulator having the features of claim 1.

[0010] A pressure accumulator assembly is created. The pressure accumulator assembly comprises a piston located within a pressure vessel. The pressure vessel contains a piston stop. The piston stop is located radially outside a preload element or spring located between the pressure vessel and the piston within the pressure vessel. A support bracket is located at one end of the pressure vessel, aligned with the spring. The external piston stop and the support bracket reduce stresses due to bearing forces when the pressure accumulator assembly is fully loaded. By reducing stresses due to bearing forces, the pressure accumulator assembly can be manufactured from a steel casting or a plastic molded part without compromising its loading capacity.

[0011] Further areas of applicability will become clear from the description given here. Of course, the description and specific examples are intended only for illustration and not to limit the scope of this disclosure. DRAWINGS

[0012] The drawings described here serve only for illustration and are not intended to limit the scope of the present disclosure in any way. Fig. 1 is an isometric front view of a pressure storage arrangement according to the principles of the present invention; Fig. 2 is a side view of the pressure storage arrangement according to the principles of the present invention; Fig. 3 is a front view of the pressure storage arrangement according to the principles of the present invention; Fig. 4 is a front view of the pressure storage arrangement according to the principles of the present invention; and Fig. Figure 5 is a cross-sectional view of the pressure storage arrangement according to the principles of the present invention. DETAILED DESCRIPTION

[0013] The following description is purely illustrative in nature and is not intended to limit the present disclosure, its application or uses.

[0014] In the Fig. 1-5 is a pressure accumulator arrangement according to the principles of the present invention, generally specified by reference numeral 10. The pressure accumulator 10 is an energy storage device in which a non-compressible hydraulic fluid is held under pressure by an external source. In the given example, the pressure accumulator 10 is a spring-loaded pressure accumulator that exerts a pressure force on the hydraulic fluid in the pressure accumulator 10, as described in more detail below. The pressure accumulator 10 is preferably used in the hydraulic control system of an automatic transmission (not shown) to enable stop-start operations; however, the pressure accumulator 10 can be used in various other environments, such as fuel injection systems, air conditioning systems, etc., without departing from the scope of the present invention.

[0015] The pressure accumulator 10 comprises a pressure vessel 12 and an end cap 14. The pressure vessel 12 is generally cylindrical and has a closed end 16 and an open end 18 opposite the closed end 16, as shown in Fig. Figure 5 is best seen. The open end 18 communicates with a cavity 20, which is defined by an inner surface 22 of the container 12. The inner surface 22 has two sections: a first or small section 24 and a second or large section 26. The first section 24 is located in close proximity to the closed end 16 and has a first diameter. The second section 26 is located between the first section 24 and the open end 18 and has a second diameter. The second diameter is larger than the first diameter. The interface or junction between the first and second sections, 24 and 26, forms a radially extending piston stop 28.

[0016] A piston 30 is arranged in the pressure vessel 12 and is displaceable along an axis "A". The piston 30 comprises a disk plate section 32 and a radially extending rim section 34. The rim section 34 extends towards the closed end 18 of the pressure vessel 12 and has a distal end face 36. The piston 30 is slidably arranged in the second section 26 of the pressure vessel 12 and has an outer diameter that is approximately equal to the second diameter of the second section 26. The piston 30 is sealed at the inner surface 22 of the pressure vessel 12 by a radial seal 38.

[0017] A preloading element or spring 40 is arranged in the cavity 20 of the pressure vessel 12 between the closed end 16 and the piston 30. A first end 42 of the spring 40 contacts the closed end 16, while a second end 44 of the spring 40 contacts an inner surface 46 of the piston disc section 32 radially inside the rim section 23. The spring 40 preloads the piston 30 towards the open end 18 of the pressure vessel 12.

[0018] The end cap 14 is connected to the pressure vessel 12 and arranged on the open end 18. The end cap 16 includes a radial seal 50 that seals the end cap 16 against the inner surface 22 of the pressure vessel 12. The end cap 14 is attached to the pressure vessel 14 by a radial flange 52 arranged around the open end 18. In the given example, the end cap 14 is fastened by bolts 5 extending through the flange 52 and the end cap 14, or by some other type of mechanical fastener. However, if the pressure vessel 12 is made of plastic, the end cap 14 is preferably welded to the flange 52.

[0019] The end cap 14 has an inlet / outlet opening 54 that communicates with a channel 56 formed in the end cap 14. The channel 56 communicates with an opening 58 in the end cap 14. The opening 58 is recessed in the end cap 14 and communicates with an outer surface 60 of the piston 30 in the cavity 20. The inlet / outlet opening 54 also communicates with a tube or passage 62. The tube 62 is attached to the end cap 14 by a connecting ring 64, which has an opening for receiving the tube 62 and an opening for receiving a fastening element such as a bolt 66 to secure the connecting ring 64 and thus the tube 62 to the end cap 14, as shown in Fig. 3 is best seen. A similar connecting ring 68 is shown at the opposite end of the tube 62, although it should be noted that the tube 62 may be connected to the end cap 14 or any other component in any other way without deviating from the scope of the present invention.

[0020] The pressure storage arrangement 10 further comprises a support beam 70, which is connected to an outer surface 72 of the closed end 16 of the pressure vessel 12, as shown in Fig.Figure 4 is best seen here. The support bracket 70 comprises a first flange section 74 connected to the outer surface 72. The first flange section has a semicircular or circular shape, aligned with the first end 42 of the spring 40 in the pressure vessel 12. The support bracket 70 also comprises a second flange section 76 extending from the first flange section 74. The second flange section 76 is shown forming a right angle with the first flange section 74; however, it should be noted that the second flange section 76 can have other shapes and configurations with respect to the first flange section 74 without deviating from the scope of the present invention. The second flange section 76 is designed for connection to a fixed component in a transmission, such as the transmission housing.In the given example, the second flange section 76 has a bolt hole 78, although it should be noted that various other methods of attachment can be used without deviating from the scope of the present invention. The support beam 70 also has a support rib 80 along its circumference to provide it with strength.

[0021] The pressure accumulator assembly 10 is charged during operation when pressurized hydraulic fluid enters the end cap 14 through the tube 62 and contacts the piston 30. The piston 30 is driven against the preload force of the spring 40. When the distal ends 36 of the piston 40 contact the stop 28, the piston 40 is in its maximum loaded state. Accordingly, the forces acting on the pressure vessel 12 are distributed along the stop 28 and at the point where the spring 40 contacts the closed end. By distributing the bearing forces of the piston 30 and the spring 40 across the pressure vessel 12, the stress on it is reduced, enabling it to withstand a greater force load. This allows the pressure vessel 12 to be manufactured using steel castings or plastic molds without reducing the charging capacity of the pressure accumulator assembly 10.Increased manufacturing flexibility offers cost savings and weight reductions, which in turn increase the performance of the vehicle.

[0022] The description of the invention is essentially purely exemplary, and any modifications that do not deviate from the core of the invention are to be considered within the scope of the invention. Such modifications are not considered a deviation from the inventive concept or the scope of the invention.

Claims

[1] Pressure accumulator (10) comprising: a housing (12) having a closed end (16) and an open end (18), the housing (12) having an inner surface (22) defining a cavity (20) and having a stop (28) disposed in the cavity (20); an end cap (14) disposed over the open end (18) of the housing (12), the end cap (14) having an inlet and an outlet (54) communicating with the cavity (20) for transferring a hydraulic fluid into and out of the cavity (20); a piston (30) disposed in the housing (12) between the stop (28) and the end cap (14), the piston (30) being sealed on the inner surface (22) and being displaceable along an axis; and a preloading element (40) disposed in the housing (12) and located axially between the closed end (16) of the pressure vessel (12) and the piston (30), the preloading element (40) being configured to preload the piston (30) toward the open end (18); and a support element (70) coupled to an outer surface (72) of the closed end (16) of the housing (12), wherein the piston stop (28) is arranged radially outside the preloading element (40) and wherein the support member (70) is at least partially aligned with a portion of the preloading member (40) where the preloading member (40) contacts the inner surface (22) of the closed end (16) of the housing (12). [2] The accumulator (10) according to claim 1, wherein a radius of the piston (30) is greater than a radius of the preloading element (40). [3] Accumulator (10) according to claim 1, wherein the stop (28) is formed in the inner surface (22) of the housing (12) and divides the housing (12) into a first portion (24) having a first diameter and a second portion (26) having a second diameter, the first diameter being smaller than the second diameter and the piston (30) being arranged in the second portion (26). [4] The accumulator (10) of claim 3, wherein the piston (30) has a diameter approximately equal to the second diameter of the second portion (26) of the cavity (20). [5] Pressure accumulator (10) according to claim 1, wherein the pressure vessel (12) is made of a cast steel part or a molded plastic part. [6] Pressure accumulator (10) according to claim 1, wherein the stop (28) is a radially oriented surface portion of the inner surface (22) of the housing (12). [7] Accumulator (10) according to claim 1, wherein the piston (30) has a disc plate portion (32) and an axially extending rim portion (34), the disc plate portion (32) being oriented perpendicular to the axis and the rim portion (34) extending towards the closed end (16) of the housing (12). [8] The accumulator (10) of claim 7, wherein the rim portion (34) has a distal end surface (36) configured to contact the stop (28) when the accumulator (10) is fully charged with the hydraulic fluid. [9] The accumulator (10) of claim 1, wherein the support bracket (70) includes a first flange portion (74) connected to the outer surface of the closed end (16), the first flange portion (74) having a semi-circular shape or a circular shape aligned with an end (42) of the preloading member (40) contacting the inner surface (22) of the cavity (20) at the closed end (16), and the support bracket (70) further includes a second flange portion (76) extending from the first flange portion (74), the second flange portion (74) being configured for connection to a fixed component.

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