BACKGROUND

[0001] The present invention relates to a hydraulic unit for an automotive chassis control system, such as an anti-lock braking system. More specifically, the present invention relates to an assembly and method for assembling the hydraulic unit and a mounting bracket. Hydraulic units are typically mounted to a vehicle by way of a bracket and at least one fastener.

SUMMARY

[0002] In one embodiment, the invention provides a hydraulic unit assembly including a hydraulic unit and a mounting bracket coupled to the hydraulic unit and configured to be mounted to a vehicle, the mounting bracket having an aperture. The hydraulic unit includes a motor, a body, and an accumulator, the accumulator having an accumulator cover extending from the body. At least a portion of the accumulator cover is received in the aperture in the mounting bracket.

[0003] In another embodiment the invention provides a method of assembling a hydraulic unit and a mounting bracket. The method includes providing the hydraulic unit having a body and an accumulator cover extending from the body, providing a mounting bracket having an aperture, positioning at least a portion of the accumulator cover in the aperture in the mounting bracket, and securing the mounting bracket to the hydraulic unit with a fastener.

[0004] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Fig. 1 is a perspective view of a hydraulic unit assembly according to an embodiment of the invention.

[0006] Fig. 2 is an exploded view of the hydraulic unit assembly of Fig. 1.

[0007] Fig. 3 is a cross section view of the hydraulic unit assembly of Fig. 1 taken along line 3 — 3 and mounted to a vehicle. [0008] Fig. 4 is an enlarged cross section view of a portion of Fig. 3 showing an interface of an accumulator cover, an isolator, and a bracket.

[0009] Fig. 5 is an enlarged exploded perspective view of the accumulator cover and isolator shown in Fig. 2.

DETAILED DESCRIPTION

[0010] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

[0011] Fig. 1 illustrates a hydraulic unit assembly 10 for an automotive chassis control system, such as an anti-lock braking system. The hydraulic unit assembly 10 includes a hydraulic unit 14 and a mounting bracket 18 for mounting the hydraulic unit 14 to a vehicle 22 (shown in Fig. 3). As best shown in Fig. 2, the hydraulic unit 14 includes a pump housing or body 26, a motor 30 extending from the body 26, a first accumulator cover 34, a second accumulator cover 34', and an electronic control module 38.

[0012] The motor 30 is coupled to a first side of the body 26 and drives a hydraulic pump (not shown) for receiving a low-pressure brake fluid and pressurizing the fluid to a high pressure brake fluid.

[0013] The electronic control module 38 is coupled to a second side of the body 26 opposite the first side and includes a connector 42, shown in Fig. 3, for communicating with a vehicle electronic control system, as is well understood in the art. The electronic control module 38 controls operation of the motor 30 and the distribution of a brake fluid for an anti- lock braking operation, as is understood by those skilled in the art.

[0014] The body 26 includes an aperture 46 for receiving a shaft of the motor 30, first and second accumulator chambers 50, 50' (Fig. 3) positioned within the body 26, and first and second accumulator openings 54, 54' for communicating with first and second accumulator chambers 50, 50', respectively. The first and second accumulator covers 34, 34' extend from the body 26 and are coupled to a third side of the body 26 to cover the first and second accumulator openings 54, 54', respectively. Fluid communication is established between the first and second accumulator chambers 50, 50' and the first and second accumulator covers 34, 34', respectively, by way of the first and second accumulator openings 54, 54'. The first accumulator chamber 54 and first accumulator cover 34 together define a first accumulator 58. The second accumulator chamber 54' and second accumulator cover 34' together define a second accumulator 58'. The first and second accumulators 58, 58' receive the high pressure brake fluid and store the fluid until the fluid is needed for a braking operation, as is understood by those skilled in the art. In the illustrated construction, two accumulators 58, 58' are employed. In other constructions, the hydraulic unit 14 may include only one accumulator or more than two accumulators.

[0015] Fig. 5 is an enlarged view of the accumulator cover 34 and an isolator 78. Fig. 4 is an enlarged cross section view of the accumulator cover 34 and isolator 78 assembled between the mounting bracket 18 and the hydraulic unit 14. It is to be understood that, in one embodiment, the first and second accumulator covers 34, 34' are substantially the same and first and second isolators 78, 78' are also substantially the same. Therefore, these components are given similar reference numerals and can be described with respect to the same figures.

[0016] With reference to Figs. 4 and 5, the accumulator covers 34, 34' are generally cup- shaped and at least partially define a portion of the respective accumulators 58, 58' for storing the high pressure brake fluid. Each accumulator cover 34, 34' includes a side wall 62 having an outer surface including a plurality of recesses or grooves 66. In the illustrated construction, the accumulator covers 34, 34' each include three recesses or grooves 66; however, more or fewer recesses or grooves may be employed in other constructions. An accumulator flange 70 extends substantially radially from one end of the side wall 62 and sealingly engages the body 26 of the hydraulic unit 14 surrounding the respective accumulator opening 54, 54'. At the other end of the side wall 62 is a closed end 74 that cooperates with the side wall 62 to define the cup-shape. In the illustrated construction, the accumulator covers 34, 34' are substantially cylindrical and define a central axis 80 (Fig. 5); however, in other constructions, the accumulator covers may have other cup-like shapes having a side wall or side walls and a closed end.

[0017] First and second isolators 78, 78' made at least partially of a resilient or elastic material are configured to fit snugly around the outer surface of the first and second accumulator covers 34, 34', respectively. In the illustrated construction, each of the isolators 78, 78' has a substantially tubular body portion 82 and a flange 86 extending therefrom in a radially outward direction. The tubular body portion 82 of the isolators 78, 78' are coaxial with the axis 80 when mounted on the respective accumulator covers 34, 34' (Fig. 5). As shown best in Figs. 4 and 5, the tubular body portions 82 each include an outer surface having axial ribs 90 extending substantially parallel to the central axis 80 (i.e., axially), and a bore 94 having an inner surface that includes a plurality of projections 98 sized, spaced and positioned to mate with the recesses or grooves 66 in the outer surface of the respective accumulator covers 34, 34'.

[0018] In the illustrated embodiment, the first and second isolators 78, 78' are coupled to the respective accumulator covers 34, 34' by way of the snug fit (e.g., friction fit) and, additionally, by way of the mated grooves 66 and projections 98. To compensate for tolerances, the plurality of projections 98 are staggered over various axial heights such that at least one of the plurality of projections 98 will line up with a groove or recess 66 when the isolators 78, 78 are assembled. Although a plurality of grooves 66 and projections 98 are employed in the illustrated construction, in other constructions, only one groove and projection may be provided. Furthermore, the at least one groove and projection may be continuous or broken. In other constructions, the inner surface of the tubular body portion 82 could include the recesses or grooves, and the outer surface of the accumulator covers 34, 34' could include the projections. In yet other constructions, the isolators 78, 78 'could be otherwise coupled to the accumulator covers 34, 34', such as, but not limited to, by way of adhesive, an overmolding process, or any other suitable means. It is also possible that no separate isolating part is provided between the accumulator covers 34, 34' and the mounting bracket 18 but instead is integrally formed as part of the accumulator covers 34, 34' or the bracket 18. [0019] The mounting bracket 18 is coupled to a fourth side of the body 26 of the hydraulic unit 14 by way of a fastener assembly 100 (see Fig. 2). In the illustrated construction, the fastener assembly 100 includes a pin 102, an isolating member 114, a washer 118 and a bushing or nut 122. The pin 102 passes through an aperture or slot 106 in the mounting bracket 18 and includes a threaded end 110 that is secured tightly into the body 26 of the hydraulic unit 14. The isolating member 114 is sandwiched between the body 26 and the washer 118. The bushing or nut 122 is threaded onto the opposite end of the pin 102 and holds the washer 118 firmly against the isolating member 114 to compress the isolating member 114 between the body 26 and the washer 118. A portion of the isolating member 114 is positioned between the pin 102 and the mounting bracket 18 to isolate the pin 102 from the mounting bracket 18. The isolating member 114 also includes a first toroidal portion 126 that is sandwiched between the mounting bracket 18 and the body 26, and a second toroidal portion 130 that is sandwiched between the mounting bracket 18 and the washer 118. The washer 118 has a surface approximately equal in size to an abutting surface of the isolating member 114 to evenly distribute the pressure exerted by the tightened bushing or nut 122. In other constructions, other types of fasteners or fastener assemblies may be employed to couple the mounting bracket 18 to the body 26 of the hydraulic unit 14.

[0020] The mounting bracket 18 is preferably an L-shaped bracket including a first substantially planar portion 134 and second substantially planar portion 138 angled approximately 90 degrees from the first planar portion 134. The first planar portion 134 includes a first aperture 142 and a second aperture 146 for receiving the first accumulator cover 34 and the second accumulator cover 34', respectively. The reception of the accumulator covers 34, 34' in the apertures 142, 146 in the mounting bracket 18 constitutes a mechanical connection between the hydraulic unit 14 and the mounting bracket 18. The mechanical connection limits the relative movement (e.g., limits degrees of freedom) of the hydraulic unit 14 with respect to the mounting bracket 18 such that only one fastener is required to securely fasten the hydraulic unit 14 to the mounting bracket 18 (e.g., preferably completely eliminating all degrees of freedom). Six degrees of freedom generally exist for a rigid body in three-dimensional space: translational movement in three directions (x, y, and z axes) and rotational movement about the three axes. The reception of the accumulator covers 34, 34' in the mounting bracket 18 eliminates two translational degrees of freedom and all three rotational degrees of freedom. In the alternate construction having only one accumulator cover 34, the reception of the accumulator cover 34 in the mounting bracket 18 eliminates two translational degrees of freedom and two rotational degrees of freedom. Other constructions having more than two accumulator covers positioned in the mounting bracket 18 and other constructions in which one or more accumulator covers are received in different locations on the mounting bracket 18 are also possible and may result in the elimination of different degrees of freedom.

[0021] The second planar portion 138 is fastened to the body 26 and, in the illustrated construction, includes the aperture or slot 106 for receiving the fastener assembly 100. The use of a single fastener (e.g., the fastener assembly 100) between the body 26 and the mounting bracket 18 eliminates the remaining degrees of freedom. In the illustrated construction, the fastener assembly 100 eliminates the remaining translational degree of freedom of the hydraulic unit 14 with respect to the mounting bracket 18. In the alternate construction having only one accumulator cover 34, the use of a fastener eliminates the remaining translational degree of freedom and the remaining rotational degree of freedom. In other constructions, the use of a fastener may only eliminate some of the remaining degrees of freedom, although removing all is preferred.

[0022] In other constructions of the mounting bracket 18, the first and second planar portions 134, 138 may be oriented at different angles relative to each other, and the first and second apertures 142, 146 and the slot 106 may be located in other locations on the mounting bracket 18 including being positioned on the same planar portion.

[0023] In the illustrated construction, the first and second apertures 142, 146 are through- holes sized to receive the first and second isolators 78, 78' coupled to the first and second accumulator covers 34, 34', respectively, as described above. The mounting bracket 18 preferably includes a smooth lip 150, 154 around each aperture 142, 146. The lips 150, 154 are rounded and project substantially normal to the first planar portion 134 in a direction away from the hydraulic unit 14. The lips 150, 154 engage the tubular body portions 82 of the isolators 78, 78', and more specifically, the axial ribs 90. The first planar portion 134 engages the flanges 86 of the isolators 78, 78'. The axial ribs 90 on the outer surfaces provide added isolation between the isolators 78, 78' and the mounting bracket 18 by reducing the surface area of the isolators 78, 78' in contact with the mounting bracket 18 and by facilitating resilient deformation of the isolators 78, 78'. The tubular body portions 82 are positioned substantially between the accumulator covers 34, 34' and lips 150, 154 of the mounting bracket 18, and the flanges 86 are positioned substantially between the body 26 of the hydraulic unit 14 and the first planar portion 134 of the mounting bracket 18. Thus, the isolators 78, 78' reduce or eliminate the transmission of vibrations by preventing direct contact between the accumulator covers 34, 34' and the mounting bracket 18, and by providing a vibration-absorbing member therebetween. In other constructions, the apertures 142, 146 for receiving the isolators 78, 78' and accumulator covers 34, 34' need not take the form of the illustrated circular through-holes, but could include slots, recesses, voids, cavities, the like, and/or any other suitable members.

[0024] The mounting bracket 18 also includes a pair of mounting flanges 158 extending from the first planar portion 134 in a direction away from the hydraulic unit 14. In the embodiment depicted, the mounting flanges 158 each include a mounting portion substantially parallel to the first planar portion 134 and including a pair of apertures 162 for receiving fasteners 166 to couple the mounting bracket 18, and ultimately the hydraulic unit 14, to the vehicle 22, as shown in Fig. 3.

[0025] In operation, the hydraulic unit 14 is fitted with isolators 78, 78' over the accumulator covers 34, 34', and the isolators 78, 78' are positioned in the apertures 142, 146 in the mounting bracket 18. The isolators 78, 78' are preferably secured to the accumulator covers 34, 34' by the snug friction fit and by engagement between the projections 98 and recesses 66. The mounting bracket 18 is coupled to the hydraulic unit 14 by way of a fastener, such as the fastener assembly 100. Thus, the isolators 78, 78' reduce the transmission of vibrations by preventing direct contact between the accumulator covers 34, 34' (and, further, the hydraulic unit 14) and the mounting bracket 18. Furthermore, by positioning at least one of the accumulator covers 34, 34' in an aperture 142, 146 in the mounting bracket 18, the number of fasteners required to mount the hydraulic unit 14 to the mounting bracket 18 is reduced because degrees of freedom are removed, as described above. This also provides ease of assembly as fewer torquing operations are required when fewer fasteners are required.

[0026] Various features and advantages of the invention are set forth in the following claims.