Wire form spring for transport security and housing unit with the wire form spring

Abstract

The invention relates to a wire form spring (10) for securing during transport, comprising a body (11) which, in a relaxed state of the wire form spring (10), is formed symmetrically with respect to a plane of symmetry S, comprising a central arch (12) through which the plane of symmetry S runs, a first straight leg (13) and a second straight leg (13'), the first straight leg (13) adjoining a first end (12a) of the central arch (12) and the second straight leg (13') adjoining a second end (12b) of the central arch (12), the first straight leg (13) and the second straight leg (13') running parallel to one another and to the plane of symmetry S in the relaxed state. The first straight leg (13) opens into a first U-shaped section (14) via a first deflection section (15), and the second straight leg (13') opens into a second U-shaped section (14') via a second deflection section (15'), wherein the two U-shaped sections (14, 14') each span a plane which is perpendicular to the plane of symmetry S. The first U-shaped section (14) opens into a first end section (17) via a third deflection section (16), and the second U-shaped section (14') opens into a second end section (17') via a fourth deflection section (16').

Description

The invention relates to a three-dimensional wire-form spring for securing the transport of an object accommodated in a housing, in particular a valve accommodated in a cylinder. The invention also relates to a housing unit with inserted wire form spring.In the prior art, for example, retaining clips, wire form springs, clips or the like are used to secure the components in a housing in order to temporarily close the housing in such a way that the internal components, such as a valve unit, which can be part of a slave cylinder of a disengagement system, cannot slip or fall out during transport until installation in a hydraulic system.For example, it is known to use a U-shaped retaining clip made of plastic with legs which are parallel to one another at least in sections and which is pushed into a circumferential opening in a cylindrical valve housing. The legs are provided with a hook at each end in order to engage from the inside into projections of a wall of the housing. Housings of this type are predominantly produced in an injection molding process. In this case, what are known as "slides" are usually used in order to form inner contours of the housing. The slide is guided perpendicularly to a longitudinal axis of the housing into the path of the injection molding compound, so that it forms a boundary for the injection molding compound.In order to form the projections on which the retaining clip is to be clamped, the slide must have a very thin wall thickness, which leads to problems during the production process, since the slide often no longer has the necessary stability in the case of thin wall thicknesses.It is an object of the present invention to specify a wire-form spring for transport securing which can also be used in a housing without inner projections. Furthermore, it is an object of the invention to specify a housing unit having such a wire-form spring.The object is achieved by a wire form spring for transport safety according to claim 1 and by a housing unit with such a wire form spring according to claim 7.The wire form spring is formed with a body which, in a relaxed state, is formed symmetrically with respect to a plane of symmetry S, having a central arc through which the plane of symmetry S runs, a first straight leg and a second straight leg, wherein the first straight leg adjoins a first end of the central arc and the second straight leg adjoins a second end of the central arc, wherein the first straight leg and the second straight leg, in the relaxed state, run parallel to one another and to the plane of symmetry S. The first straight leg opens via a first deflection section into a first U-shaped section and the second straight leg opens via a second deflection section into a second U-shaped section, wherein the two U-shaped sections each span a plane which is perpendicular to the plane of symmetry S. The first U-shaped section opens via a third deflection section into a first end section and the second U-shaped section opens via a fourth deflection section into a second end section.The term "deflection section" is used within the scope of the invention for a section with a bend of more than 60°, in particular of approximately 90°, measured as a smaller angle between two legs of the deflection section. The deflection sections are preferably formed as bends of a wire from which the body of the wire form spring is formed.The body of the wire-form spring is formed symmetrically with respect to the plane of symmetry which runs through the central arc. That is, the plane of symmetry divides the central arc into two equal halves. The central arch is adjoined on one side of the central arch by a first straight leg and on a second side of the central arch by a second straight leg. These two legs can be pressed against one another in the direction of the axis of symmetry, for example by hand or with an auxiliary means such as a clamp, in order to compress the wire-form spring. The wire form spring thereby reduces its dimension perpendicular to the axis of symmetry in comparison to its relaxed state. The central arc can be formed in particular in a semicircular manner.In this state of the prestressing of the wire-form spring, the latter can be introduced into a receptacle of a housing, in particular into a central receptacle which runs along a longitudinal axis L of a cylindrical housing, and can be anchored there by simply releasing the pressure on the two straight legs. The two U-shaped sections serve as anchoring regions which can engage in corresponding circumferential or edge-side recesses of the housing. Thus, no separate projections need to be provided in the interior of the housing, which can lead to problems during the production process, for example an injection molding process. This simplifies and accelerates the production process and saves production costs.According to an embodiment of a wire form spring according to the invention, the first end portion and the second end portion in the relaxed state extend parallel to each other and to the plane of symmetry S. In other words, the first and the second end portion also extend parallel to the first and the second straight leg. This gives the U-shaped portion appropriate rigidity.The wire form spring according to the invention can be produced in particular from a metal wire, since this can be easily moved into the desired shape. Alternatively, however, a wire-form spring made of plastic is also possible.An advantageous further development of the invention provides that the body of the wire-form spring is formed in one piece. In other words, the wire-form spring is continuously produced from a single wire, in particular a metal wire.According to a further embodiment, each of the deflection sections is designed as a 90° arc. This achieves a particular stability of the wire-form spring and, in particular, the U-shaped sections are given a high rigidity, which is advantageous for the strength of the anchoring.Furthermore, it has proven to be favorable if the first and second legs, the first and second U-shaped section and the first and second end section are formed with a uniform wire thickness. In this way, the wire-form spring increases overall in stability.The invention also relates to a housing unit which comprises a housing which has a cylindrical section, wherein a central receptacle is formed in the cylindrical section, said central receptacle having a longitudinal axis I which coincides with a longitudinal axis L of the cylindrical section. Furthermore, two circumferential openings which are opposite one another perpendicular to the longitudinal axis L are formed in the cylindrical section, wherein a wire-form spring according to one of the preceding claims is inserted into the central receptacle such that its first U-shaped section and its second U-shaped section engage in each case in a circumferential opening from the central receptacle.The housing of the housing unit according to the invention can be, for example, a valve housing, in particular a housing for inlet valves of a central release device or a release device, as is used for releasing a clutch. The housing comprises in particular a cylindrical section in which a valve unit can be accommodated. When transporting such a housing up to a station for assembly, it is important that a valve unit already inserted in the housing is securely held in place, so that no parts can fall out of the central receptacle via an open end face thereof.For this purpose, the housing has two circumferential openings which extend completely or partially outwards from the central receptacle through a circumferential wall of the cylindrical section. The circumferential openings serve for the engagement of the U-shaped sections of the wire form spring. Because the U-shaped sections span a plane, i.e. delimit a surface, secure retention in the circumferential openings is ensured. The expression "circumferential-side" is to be understood within the scope of the invention such that the openings are formed in a circumferential wall of the cylindrical section, i.e. in the cylindrical circumferential wall, over an angular range of the circumference. In other words, the openings are arc-shaped elongated holes. These can extend through the entire thickness of the circumferential wall, thus thus passing through from the central receptacle to the outside, or else from the central receptacle only over a part of the thickness of the circumference.Preferably, the U-shaped sections of the wire form spring do not project outwards beyond the respective circumferential opening in the inserted state. In other words, the wire-form spring is matched to the dimensions of the cylindrical section of the housing unit in such a way that a width of the wire-form spring perpendicular to its axis of symmetry S in the relaxed state of the wire-form spring is smaller than an outer diameter of the cylindrical section of the housing. In this way, the wire form spring used does not impair the handling of the housing unit during transport and during assembly.According to a further advantageous embodiment of the invention, each of the circumferential openings extends over a circumferential angle range between 90° and 170°. In this way, the U-shaped sections can be formed relatively large in relation to the outer diameter of the cylindrical section of the housing and thus ensure a secure hold.Furthermore, it has proven advantageous if the central arc, in the inserted state of the wire form spring, protrudes at least partially outwards beyond an end face of the central receptacle. In particular, a part of the first and second straight legs may also protrude outward from the central receptacle in the state in which the wire shape spring is inserted into the cylindrical housing portion. This has the advantage that the wire form spring can be simply gripped at the central bend after the housing unit has been transported and can be compressed by compression by hand or with the aid of a tool such as pliers on the first and the second straight leg. In this way, the wire-form spring can be disassembled again with little work.Further features, advantages and effect of the invention are evident from the following description of preferred exemplary embodiments of the invention and from the attached figures. These show: FIGS. 1 ato 1 d show a housing unit with a securing clip according to the prior art from different perspectives; FIG. 2 shows an embodiment of a wire-form spring according to the invention; FIGS. 3 ato 3 d show the wire form spring from FIG. 2 inserted into a housing from different perspectives; FIGS. 4a to 4 show a process of inserting the wire form spring according to the invention into the housing; and FIG. 5 shows a detail of an injection molding tool for producing a housing according to the invention.Referring to the illustrations of Figures 1a to 1b, a valve unit 100 will first be described for illustrative purposes. This comprises a slave cylinder housing 101, for example a slave cylinder housing for a clutch disengagement device (not shown in the figure), which has a portion forming a valve housing 102. As can be seen, the valve housing 102, which is of cylindrical design, has a central opening 103, in which a valve 104 is inserted.In order to protect the valve 104 from falling out, for example during transport, a forked retaining clip 106 is inserted in a circumferential recess 105, which clip is supported on inner projections 107 of the valve housing 102. During the assembly of the valve unit 100, the valve 104 is first pushed into the central opening 103 and locked with the retaining clip 106 or secured against falling out. Subsequently, for assembly reasons, a sealing disk 108 is first pushed onto the slave cylinder housing 101.Referring now to FIGS. 1 cand 1 d, a problem in the manufacture of such a valve housing 102 is illustrated. When the valve housing 102 is produced from a plastic in an injection molding process, an injection molding tool 109 is used in which a first slide 110 for forming the central opening 103 (see FIG. 1 b) and a second slide 111 for forming the circumferential recess 105 (see FIG. 1 b) are inserted. As can be seen, an available width X for the second slide 111 is too small to allow smooth manufacturing.FIG. 2 shows an embodiment of a wire form spring 10 in a perspective view, which forms a transport securing means at the location of the above-described retaining clip. As can be seen in the figure, the wire-form spring 10 has a body 11 which is formed symmetrically with respect to a plane of symmetry S. The plane of symmetry S extends through a central arc 12, which is designed here as a semicircular arc.At a first end 12a and at a second end 12b, the central arch 12 opens into a first straight leg 13 and into a second straight leg 13', respectively. The first and the second straight leg 13, 13' extend in the embodiment shown parallel to one another and parallel to the plane of symmetry S. When the wire form spring 10 according to the invention is inserted, the first straight leg 13 and the second straight leg 13' form respective engagement surfaces for a finger or a tool of an assembler in order to compress the wire form spring 10 for insertion into a housing.At their respective ends opposite the central arch 12, the first straight leg 13 and the second straight leg 13' pass into a first deflection section 15 and a second deflection section 15', respectively. The first and second turn portions 15, 15' form respective bends of the metal wire from which the wire form spring 10 is formed by 90°. The first deflection section 15 and the second deflection section 15' lead away from the plane of symmetry S in opposite directions.The first deflection section 15 opens into a first U-shaped section 14, whereas the second deflection section 15' opens into a second U-shaped section 14'. Both U-shaped sections 14, 14' each span a plane which, in the present embodiment, extends perpendicular to the plane of symmetry S of the central arc 12. The expression "span a plane" means, within the scope of the invention, a plane which intersects the body 11 of the wire form spring 10 centrally in the entire region of the respective U-shaped section 14 or 14', i.e. along a central axis of the wire of the wire form spring 10. Since the wire form spring 10 is formed symmetrically, the two planes which are spanned by the respective U-shaped sections 14, 14' coincide, i.e. they form a plane which here runs perpendicular to the plane of symmetry S.The respective U-shaped sections 14, 14' end in a third deflection section 16 or a fourth deflection section 16', which again form arcs of 90°. In the embodiment shown, the third and fourth deflection sections 16, 16' form respective end-side bends of the wire-form spring, which open into a first end section 17 and into a second end section 17', respectively. In a relaxed state of the wire form spring 10, in which no external forces act on the latter, as is the case in the illustration of FIG. 2, the two end sections 17, 17' are parallel to one another and to the plane of symmetry S.Referring now to Figs. 3a to 3d, the wire form spring of Fig. 2 is shown from several views in a state of being inserted into a housing 20. In this case, FIG. 3 ashows the housing 20 from the front, FIG. 3 bshows a plan view, FIG. 3 cshows a lateral sectional view and FIG. 3 dshows a perspective view. The housing 20 with the inserted wire form spring 10 together form an embodiment of a housing unit 1 according to the invention. As can be seen, the housing 20 has a cylindrical section 21, wherein a central receptacle 22 is formed in the cylindrical section 21, which receptacle has a longitudinal axis I, which coincides with a longitudinal axis L of the cylindrical section 21. A valve 24 is accommodated in the central receptacle 22 of the cylindrical section 21. In the cylindrical section 21, two circumferential openings 23, 23' are furthermore formed which are opposite one another perpendicular to the longitudinal axis L. In the case shown, the housing 20 is a valve housing which can be part of a slave cylinder housing of a disengagement device (not shown in the figure), for example.Inserted into the central seat 22 is a wire form spring 10, as shown in FIG. 2, such that its first U-shaped portion 14 and its second U-shaped portion 14' engage in each case in a circumferential opening 23, 23, from the central seat 22, but do not project outwards beyond said opening. Furthermore, the central arc section 12 of the wire-form spring 10 projects outwards beyond an end face 22 aof the central receptacle 22, as can be seen particularly clearly in FIG. 3 b. In this way, the inserted wire form spring 10 can be easily pulled out of the housing 20 again. In contrast, the first and the second end section 17, 17' do not protrude beyond the end face 22a, because these are not required for pulling the wire form spring 10 out of the central receptacle 22.FIGS. 4 ato 4 e show a process of inserting the wire form spring 10 into the housing 20, wherein in FIG. 4 a the wire form spring 10 is shown in an insulated state in a compressed state, i.e. in a pre-tensioned state. This is effected by pressing the first straight leg 13 and the second straight leg 13' against one another manually or with a tool 30, such as a clamp (see FIG. 4 b ), so that the wire-form spring 10 is compressed in a region of the central arc 12 (see the direction of a force to be applied by the tool 30 as shown by two arrows in FIG. 4 b ).In the compressed state, the wire form spring 10 is inserted into the central receptacle 22 (see FIGS. 4 cand 4 d ). This prevents the valve 24 from falling out of the central receptacle 22, As shown in FIG. 4 c, the wire form spring 10 is tilted for insertion so that it can be introduced obliquely (see arrow). Then, the first U-shaped portion 14 is inserted into the first circumferential opening 23 and the second U-shaped portion 14' is inserted into the second circumferential opening 23 in sequence. When both U-shaped sections 14, 14' point into the respective circumferential openings 23, 23', the wire form spring 10 spreads open again (see double arrow in FIG. 4d). In FIG. 4 e, two clamping points (see double arrows) are shown, which indicate that the wire form spring 10 has locked itself in a self-locking manner.FIG. 5 shows a representation of a detail of an injection molding tool 109 for producing the housing 20 of FIGS. 3 ato 3 d. Analogously to the injection molding tool 109 of the prior art (see FIG. 1 a), the injection molding tool 109 comprises a first slide (not shown here) and a second slide 111. As can be seen in the figure, a wall of the second slide 111 which serves to form the circumferential openings 23, 23' (see FIG. 3 d) for the first and the second U-shaped section 14, 14' of the wire-forming spring 10 (see FIG. 2 ) is sufficiently wide because, in a housing according to the invention (see FIGS. 3 ato 3 d), no lateral projection has to be present in the central receptacle 22.List of reference characters1 Housing unit 10 Wire form spring 11 Body 12 Central bend 12a First end 12b Second end 13 First straight leg 13'Second straight leg 14 First U-shaped section 14' Second U-shaped section 15 First deflection section 15' Second deflection section 16 Third deflection section 16' Fourth deflection section 17 First end section 17' Second end section 20 Housing 21 Cylindrical section 22 Central receptacle 22a End side 23, 23' Circumferential opening 24 Valve 30 Tool 100 Valve unit 101 Slave cylinder housing 102 Valve housing 103 Central opening 104 Valve 105 Circumferential recess 106 Retaining clip 107 Inner projection 108 Sealing disc 109 Injection molding tool 110 First slide 111 Second slide S Plane of symmetry M Central axis Wire I Longitudinal axis Cylindrical section L Longitudinal axis receptacle

Claims

Wire-form spring (10) for transport safety, having a body (11) which, in a relaxed state of the wire-form spring (10), is formed symmetrically with respect to a plane of symmetry S, having a central arch (12) through which the plane of symmetry S runs, a first straight leg (13) and a second straight leg (13'), wherein the first straight leg (13) adjoins a first end (12a) of the central arch (12) and the second straight leg (13') adjoins a second end (12b) of the central arch (12), wherein the first straight leg (13) and the second straight leg (13') run parallel to one another and to the plane of symmetry S in the relaxed state, characterized in that, the first straight leg (13) opens via a first deflection section (15) into a first U-shaped section (14) and the second straight leg (13') opens via a second deflection section (15') into a second U-shaped section (14'), wherein the two U-shaped sections (14, 14') each span a plane which is perpendicular to the plane of symmetry S, and the first U-shaped section (14) opens via a third deflection section (16) into a first end section (17) and the second U-shaped section (14') opens via a fourth deflection section (16') into a second end section (17').Wire-form spring (10) according to Claim 1, characterized in that the first end section (17) and the second end section (17') in the relaxed state run parallel to one another and to the plane of symmetry S.Wire form spring (10) according to claim 1 or 2, characterized in that it is made of a metal wire.Wire-form spring (10) according to one of the preceding claims, characterized in that the body (11) is formed in one piece.Wire-form spring (10) according to one of the preceding claims, characterized in that each of the deflection sections (15, 15', 16, 16') is designed as a 90° arc.Wire-form spring (10) according to one of the preceding claims, characterized in that the first and second leg (13, 13'), the first and second U-shaped section (14, 14') and the first and second end section (17, 17') are formed with a uniform wire thickness.Housing unit (1) comprising a housing (20) which has a cylindrical section (21), wherein a central receptacle (22) is formed in the cylindrical section (21), said central receptacle having a longitudinal axis I which coincides with a longitudinal axis L of the cylindrical section (21), wherein two circumferential openings (23, 23') which are opposite one another perpendicular to the longitudinal axis L are furthermore formed in the cylindrical section (21), characterized in that a wire-shaped spring (10) according to one of the preceding claims is inserted into the central receptacle (22) in such a way that its first U-shaped section (14) and its second U-shaped section (14') each engage into a circumferential opening (23, 23') starting from the central receptacle (22).Housing unit (1) according to claim 7, characterised in that the U-shaped sections (14, 14') do not project outwards beyond the respective peripheral opening (23, 23').Housing unit (1) according to claim 7 or 8, characterised in that each of the circumferential openings (22, 22') extends over a circumferential angle range between 90° and 170°.Housing unit (1) according to one of Claims 7 to 9, characterized in that, in the inserted state, the central bend (12) projects at least partially outwards beyond an end face (22a) of the central receptacle (22).

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