Patent Application
20130055529
This invention relates to automotive door checks, and in particular to a compact mechanical device capable of holding an automotive door in one or more predetermined open positions with a predetermined force.
It has been found useful to check the movement of an automotive door in a number of predetermined open positions to assure convenient and safe ingress/egress of the occupants. The door is normally checked against movement in at least one open position with an effort or resistive force adequate to resist wind gusts and the effect of parking on an incline or grade.
The most common form of automotive door check is a mechanical device that resists motion by releasably storing energy in response to forced motion of the system. These devices, located between the vehicle's body structure and door, can be configured to be integral with the door hinge or separate as autonomous mechanical assemblies. Energy storage is generally achieved by a form of spring with coil and torsion arrangements being the most popular configurations. As the door is opened or closed, the door check is configured to release energy entering the check positions and to store it when moving out of the check positions. The most common method of storing energy in the spring system is by means of a cam arrangement that moves in conjunction with the door. This cam can work within the hinge to ultimately produce a torque around the pivot axis of the hinge, or can work linearly in a separate checking apparatus which produces a force vector to resist door movement at selected opening positions.
U.S. Pat. No. 5,173,991 to Carswell describes a common type of separate door checking apparatus that utilizes a molded link member to provide a cam arrangement and a pair of coil springs to releasably store energy. The coil springs are contained in a check housing and are acted upon by the molded link member via ball bearings and ball bearing retainers. The check housing is rigidly attached to the vehicle door and the molded link member is pivotally connected to the vehicle body structure. The device of Carswell provides a robust, reliable and relatively compact solution for checking the movement of an automotive door. There are numerous similar solutions that utilize rollers or sliders in place of the ball bearings of Carswell. U.S. Pat. No. 6,370,733 to Paton et. al. describes a separate checking apparatus that utilizes a molded link member or check arm and rollers. U.S. Pat. No. 6,842,943 to Hoffmann et. al. describes a separate checking apparatus that utilizes a molded check arm and sliders.
Because the automotive door check must be located between the vehicle's body structure and door, it is forced to occupy a severely restricted package space as there is limited clearance between the vehicle body structure and the door and very little volume available within the door. Additionally, the weight of the automotive door check apparatus must not be too great as a significant proportion of the door check apparatus mass resides within the door profile, which swings on a pivot and is highly sensitive to weight. In general, the manufacturing costs of automotive components are among the lowest of any comparable industry and so simple solutions with low part counts are highly desirable. The main focus of an automotive door check development is to attain the required check efforts in the smallest possible package at the lowest achievable weight and cost. Using as few components as possible is highly desirable as is the ease of assembly in to the body structure and the ability of the apparatus to withstand manufacturing processes to which the body structure is subjected. The type of spring and its related strain energy storage capability combined with the package efficiency of the actuation mechanism ultimately dictate the overall effectiveness of the automotive door check apparatus.
U.S. Patent Application 2011/0016665 to Ng shows an elegant solution of door check in which the number of components is reduced to an arm and a unitary body. The unitary body is formed with a pair of leaf springs that cooperate with the arm to store and release energy as the arm moves relative to the housing. This arrangement minimizes the number of components and thereby offers significant advantages. The use of leaf springs reduces the number of components required, but at the same time requires close control of the manufacturing process to attain the required consistency of operation. Relatively small variations in the material and dimensions can introduce variability in the characteristics of the leaf springs, that may not be acceptable to the ultimate end user of the door check.
The manufacturing tolerances affecting the characteristics of a torsion spring are easier to control. U.S. Pat. No. 6,687,953 to Leang discloses a door check device in which a torsion spring is utilized to bias rollers against the flanks of the door check arm. Whilst the torsion spring provides uniform physical characteristics, the arrangement shown in Leang utilizes a significant number of components including rollers and a housing in which the torsion spring is supported. This introduces mechanical complexity and weight to the assembly, as well as requiring assembly to the door after body has been painted as the components cannot withstand the painting process.
It is therefore an object of the present invention to provide a door check in which the above disadvantages are obviated or mitigated.
In general terms, the present invention provides a door check which has a check arm and a unitary energy storage component that cooperates with the arm as a door moves between open and closed positions. The unitary energy storage component is integrally formed as a single component that functions to store energy and facilitate assembly and handling. The unitary energy storage component utilizes a pair of torsion springs that are each connected to shoes that slide on the arm as the door opens and closes. Mounting brackets are provided on the torsion springs which allow rotary motion between the brackets and springs as they are loaded in torsion. The springs, mounting brackets and shoes are comolded as an integral unit, preferably in a single molding operation, to facilitate handling and assembly.
In accordance with one aspect of the present invention there is provided a door check for an automobile comprising:
Preferably, each of the torsion springs has a pair of legs and the legs are loaded in torsion by variation of the spacing of the shoes.
Preferably, also feet extend from the legs and the shoes are connected to the feet.
Preferably, the brackets and shoes are molded on the springs after placement of the springs in a common mold to provide a unitary structure.
An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which:
Referring therefore to
As best seen in
The arm 12 has an elongate body 20 that extends from a knuckle 22, through which the pin 14 passes. The body 20 is molded from a plastics material about a central metallic core 24. The body 20 includes a shank 26 extending from the knuckle 22 that in turn merges with a cam 28. The cam 28 is moulded to provide a generally I-shaped cross section with oppositely directed flanks 30.
The width of the cam 28, that is the lateral spacing between the flanks 30, varies along the length of the arm 12 with localized reductions in the width to provide waisted portions 32, 34, 36 at spaced locations.
Referring to
Referring again to
The legs 56 are maintained in spaced parallel relationship by means of a bracket 62. The bracket 62 is made from a plastics material, such as a glass filled nylon 66 known by the trade name Zytel, that, as described in greater detail below, is moulded about the legs 56. A fastener 64, either a nut, bolt or similar fastener, is embedded in the bracket 62 to facilitate connection of the bracket 62 to the door D. As seen in FIGS. 2,5 and 6, the bracket 62 encompasses the legs 56 so as to be retained in situ on the legs 56 but permits rotation of the leg within the bracket 62 about the longitudinal axis of the legs 56. The appropriate selection of the materials, or localised surface treatment, ensures that the bracket 62 does not adhere to the legs 56 and so permits the limited rotational movement of the legs 56 relative to the bracket 62.
The torsions springs 52, 54 are disposed on opposite sides of the arm 12 and are interconnected by a pair of shoes 70, 72. The shoes 70, 72 are secured to respective ones of the feet 60 so the springs 52, 54 and shoes 70, 72 provide a unitary structure. The shoes 70, 72 are moulded from a high density low friction plastic, such as an acetal known by the trade name Delrin, that are integrally moulded to the feet 60 to provide a unitary constntction.
As seen most clearly in
The lateral spacing of the legs 56 is such that, when the shoes 70, 72 are positioned on the shank 26, there is a small preload in the torsion springs 52, 54, to bias the convex surfaces 74 of the shoes 70, 72 against the shank 26 while offering nominal resistance to movement. The springs 52, 54 are made from a suitable spring material, such as a standard music wire.
In use, with the door closed, the shoes 70, 72 are in sliding engagement with the flanks 30 adjacent to the transition between the shank 26 and cam 28 of the arm 12. In this position, the legs 56 are in their free body condition with the shoes 70, 72 in sliding engagement with the flanks 30.
As the door opens, relative movement between the arm 12 and the unitary energy storage component 50 causes the shoes 70, 72, slide along the flanks 30. The arm 12 progressively widens and the increased spacing of the flanks 30 forces the shoes 70, 72 apart. The increased spacing of the shoes 70, 72 rotates the legs 56 in opposite directions and stores energy within the torsion springs 50, 52 by torsionally loading the legs 56. Each of the springs 52, 54 is similarly loaded and the forces acting on opposite side of the arm 12 are balanced.
Continued movement of the door, as indicated in
Continued movement of the door again forces the shoes 70, 72 apart and stores energy in the torsion springs 52, 54. A further stable position for the door is provided when the shoes 70, 72 engage the waisted portion 34 indicated at position B. Continued movement beyond the waisted portion 34 moves the shoes 70, 72 in to the waisted portion 36 and into engagement with the head 38 as shown in position C. The head 38 thus provides a stop to define the maximum opening of the door.
In that position, as can best be seen in
Return of the door to the closed position causes the shoes 70, 72 to move along the flanks 30 and through the waisted portions 32, 34 until once again on the shank 26. The profile of the cam 28 is selected to provide the required resistance to sliding motion during travel between the waisted portions, and the required retention in each of the waisted portions.
As shown schematically in
With the mold 90 open, the springs 52, 54 are placed on the track 95 and fasteners 64 placed on the boss 100. The mold 90 is closed and plastics material injected in to the cavities 98, 102. Upon solidification, the mold 90 is opened and the unitary energy storage component 50 may be removed as a single component.
The unitary energy storage component 50 is therefore is provided as a single component with the shoes 70, 72 providing sufficient structural rigidity to maintain the unit 50 as one piece. After the unitary energy storage component 50 is mounted to the door, the brackets 62 maintain the relationship between the torsion springs and thereby permit the shoes to simply function as the slides rather than being required to maintain the structurally integrity of the unitary energy storage component. The integral nature of the unitary energy storage component 50 and the absence of rollers and the like also enables the door check to be assembled with the body prior to painting, thereby simplifying subsequent assembly.
