Method for manufacturing an assembly consisting of a motor vehicle shock absorber and a protective tube that at least partially surrounds it.

Abstract

Method for producing an assembly (M) consisting of a motor vehicle shock absorber (1) and a protective tube (15) that at least partially surrounds it, wherein the protective tube (15) is first pushed over the motor vehicle shock absorber (1) and then secured against slipping off the motor vehicle shock absorber (1), wherein, for producing the assembly (M), the protective tube (15) is first pushed onto an upper damper bearing (13a) of the motor vehicle shock absorber (1) from the end of a lower damper bearing (13b), characterized in that the protective tube (15) is secured by a ring-shaped locking element (2a), which is positioned around the protective tube (15) and heated, such that the locking element (2a) contracts, clamps around the protective tube (15), and fixes the protective tube (15) at its upper end to the upper damper bearing (13a).wherein a ring-shaped device (3) is arranged at the level of the fastening groove (15a) around the ring-shaped locking element (2a) for positioning the locking element (2a), which has an annular channel (32) with a central inlet opening (30) and with outlet openings (31) which are arranged at uniform intervals along the inner diameter of the channel (32).

Description

[0001] The invention relates to a method for manufacturing an assembly consisting of a motor vehicle shock absorber and a protective tube at least partially surrounding it, with the features of the preamble of claim 1.

[0002] Such mounting assemblies are primarily used on the rear axle of motor vehicles and serve to dampen spring movements of the motor vehicle caused by uneven road surfaces, thus ensuring safe road holding and a high level of driving comfort.

[0003] The protective tube, which surrounds the vehicle shock absorber or a piston rod and damper tube of the vehicle shock absorber, serves to protect against penetrating dirt.

[0004] The damper tube is usually covered with a protective cap (also called a buffer cap), which is positioned radially between the protective tube and the damper tube. This protective cap prevents damage to the damper tube's paint finish caused by relative movement between the protective tube and the damper tube.

[0005] It is known from the general state of the art to secure the protective tube against slipping off the vehicle shock absorber using cable ties, spring washers, or clamps. The known solutions are problematic with regard to assembly and / or the automation of assembly, and sometimes require complex assembly and positioning devices. Furthermore, the space required by the known securing elements is sometimes considerable.

[0006] From DE 10 2007 046 219 A1, the applicant is aware of a support bearing for a vehicle. The support bearing has a rubber bearing that encloses one end of a shock absorber element and transmits the lateral and longitudinal forces of the shock absorber element into the vehicle body. Furthermore, damping forces of the shock absorber are transmitted to the vehicle body via the rubber bearing. A rigid rubber bearing housing encloses a rubber-elastic element of the rubber bearing, and a ball bearing allows rotational movement between a spring element and the vehicle body.

[0007] DE 10 2008 010 247 A1 describes a piston-cylinder assembly for a pivoting vehicle tailgate. The piston-cylinder assembly comprises a cylinder with a first bearing at one end. At the opposite, open end of the cylinder, a sealing and guide assembly is arranged, through which a piston rod is sealed and axially guided. A second bearing is located at the outwardly projecting end of the piston rod. A switching element and a magnet are arranged on the cylinder. Movement of the piston rod changes the magnetic field of the magnet and excites the switching element to switch. In one embodiment, the switching element and the magnet can be covered with a heat-shrink tube that extends over the entire cylinder.

[0008] From DE 40 36 704 A1, which forms the preamble of claim 1, a vibration damper with a damper cylinder is known in which a damper piston is guided. The damper piston is held by a piston rod that extends from the damper cylinder through a guide sleeve. A cover (protective tube) is fitted over the damper cylinder. A sensor winding is embedded in the cover, extending over the entire length of the cover. Two further measuring windings are located at the upper and lower ends of the cover. A permanent magnet is arranged on the guide sleeve. When the damper cylinder moves due to uneven road surfaces, the movement of the permanent magnet within the sensor winding induces a voltage that is proportional to the relative velocity of the damper cylinder and the damper piston.In the permissible end positions of the damper piston, the permanent magnet enters the area of ​​one of the measuring windings, thereby inducing an additional voltage in the measuring winding and signaling a permissible end position of the damper piston.

[0009] In JP 2008 - 138 814 A, a method for manufacturing a vibration damper is described. The vibration damper is attached to a component whose vibrations are to be controlled via fasteners. An elongated, cylindrical mass element of the vibration damper is connected to the fasteners at its ends via elastic retaining elements. End-face locking elements prevent the mass element 2 from falling off. The mass element consists of a steel body coated with an elastomeric layer. During the manufacturing process, the body is positioned in an elastomeric shrink sleeve and then conveyed past nozzles of a hot air supply unit by means of a conveyor belt. The hot air treatment shrinks the shrink sleeve, causing it to conform tightly to the body 20.

[0010] US patent 2018 / 0142726A1 describes a steering shaft made of a composite material. The steering shaft has a core structure with a first end and a second end. The core structure is covered with spirally arranged glass fibers. A U-shaped, metallic connector is firmly attached to each end. The core structure may be encapsulated by a protective element.

[0011] US Patent 6,287,209 B1 describes a drive shaft for an automobile, consisting of a metal tube welded to connecting stubs at its ends. The metal tube is further reinforced with a fiberglass layer. During manufacturing, fiberglass mats are wrapped around the metal tube. Temporary fixation is achieved using a shrink band, which is wrapped around the tube and heated.

[0012] US Patent 5,683,300 A also discloses a drive shaft consisting of a tubular body with connecting pieces at its ends. The tubular body and the connecting pieces are made of glass fiber reinforced plastic.

[0013] CN 2 090 785 U relates to a fluid- and air-separated vibration damper for automobiles, consisting of a connecting rod assembly, a guide assembly, a dust cap, an oil reservoir, and a piston assembly. It features a floating spring inside the upper chamber of a cylinder, a position limiter inside the lower chamber, and an air valve on the wall of the lower chamber. The vibration damper offers the advantage of being less susceptible to damage from vibrations, and the pressure in the oil reservoir can be adjusted via the air valve to achieve the desired vibration damping resistance.

[0014] DE 39 34 896 A1 describes a modification to the end-stop damper used to dampen impact energy introduced into a vehicle wheel that exceeds the impact energy compensable by the suspension and the main shock absorber. This is achieved by replacing previously used rubber springs with a hydraulic end-stop damper, which consists of an inner sleeve with a lower sleeve base and is telescopically displaceable within an outer sleeve with an upper sleeve base. Both sleeves are surrounded by an elastic cuff, which is attached to the outer edge of the upper and lower sleeve bases, respectively. During telescopic compression of the two sleeves, hydraulic fluid is forced through the increasingly axially lengthening annular gap, thereby converting impact energy into frictional heat.The hydraulic fluid returns to the interior enclosed by the inner and outer sleeves via a return channel located in the lower sleeve base and equipped with a check valve.

[0015] JP S57-36845Y2 relates to a damper in which a cap with an opening at the tip, the diameter of which is slightly larger than the diameter of the piston rod, is fitted over a cylinder K. The opening is located a short distance from the tip of the cylinder. A notch parallel to the axis is formed on one side of the cap, and the cap is roll-pressed at the tip of the cylinder. Furthermore, an annular projection is formed on the inside of the cap, which fits into a recess formed at the tip of the cylinder. The cap is placed over the tip of the cylinder, and both are coated with heat-shrinkable resin, which is then shrunk.

[0016] JP S61-7637U relates to an oil damper comprising: a cylindrical cylinder with a base and a stop, a piston with a piston ring slidably arranged within the cylinder, oil filled into the cylinder, and a rubber bellows that fits between part of the piston ring and the outer wall of the cylinder to enclose the oil. The cylinder and the rubber bellows, or the piston ring and the rubber bellows, are crimped by covering the outer circumference of the rubber bellows with a heat-shrinkable tube.

[0017] The invention is based on the objective of providing a method for manufacturing an assembly consisting of a motor vehicle shock absorber and a protective tube that at least partially surrounds it, which is reliable and easy to carry out and leads to a secure hold of the protective tube on the motor vehicle shock absorber.

[0018] This problem is solved by a method having the features of claim 1. Advantageous embodiments or further developments of the invention can be found in the dependent claims.

[0019] The invention relates to a method for manufacturing an assembly consisting of a motor vehicle shock absorber and a protective tube that at least partially surrounds it. The protective tube is first slid over the motor vehicle shock absorber and then secured against slipping off. To manufacture the assembly, the protective tube is first pushed onto an upper damper bearing of the motor vehicle shock absorber from the end of a lower damper bearing.

[0020] As part of the invention, it is proposed that the protective tube be secured by a ring-shaped locking element, which is positioned around the protective tube and heated. The heating is carried out in such a way that the locking element contracts and clamps itself around the protective tube.

[0021] According to a first advantageous embodiment of the invention, it is proposed that the ring-shaped locking element be heated by applying hot air. Such a method is cost-effective and highly reliable.

[0022] According to a further embodiment of the invention, the application of hot air takes place at least along a large part of the circumference of the ring-shaped locking element in order to enable the locking element to be heated as quickly and evenly as possible.

[0023] Another improved method proposes that the application of hot air be achieved by a radial flow of hot air around the circumference of the ring-shaped locking element. This further promotes rapid and uniform heating of the locking element.

[0024] To save energy and make the process cost-effective, a further development of the procedure focuses the hot air supply solely on the ring-shaped locking element. Thus, only the area of ​​the assembly containing the locking element is exposed to hot air.

[0025] Furthermore, it contributes to the cost-effectiveness of the process if the ring-shaped securing element is a commercially available heat shrink tube or at least a part thereof.

[0026] Therefore, this invention is also intended to protect the use of a commercially available shrink tube as a securing element to secure a protective tube mounted on a motor vehicle shock absorber against slipping off the motor vehicle shock absorber.

[0027] Finally, this invention also seeks protection for an assembly produced by the inventive method consisting of a motor vehicle shock absorber and a protective tube that at least partially surrounds it.

[0028] A preferred embodiment of the invention is illustrated in the figures and is explained in more detail in the following description with reference to the figures. This also highlights further advantages of the invention. Identical reference numerals, even in different figures, refer to identical, comparable, or functionally equivalent components. Corresponding or comparable properties and advantages are achieved even if no repeated description or reference is made to them. The figures are not, or at least not always, to scale. In some figures, proportions or distances may be exaggerated to more clearly emphasize features of an embodiment.

[0029] They show, each schematically Fig. 1. an assembly consisting of a motor vehicle shock absorber and a protective tube, Fig. 2 the protective tube in individual representation, Fig. 3. a heat shrink tube as a semi-finished product for the ring-shaped locking element and Fig. 4. The application of hot air to the ring-shaped locking element from view IV according to Fig. 1.

[0030] First, attention will be paid to the Fig. 1 and Fig. 2 Reference is made to this. It shows an assembly M consisting of a motor vehicle shock absorber 1 and a protective tube 15.

[0031] The motor vehicle shock absorber 1 is preferably used for rear axle damping of a motor vehicle (not shown). It has a damper tube 10 which is filled with a damping medium such as oil or air.

[0032] A piston rod 11 with a piston 12 is longitudinally movable within the damper tube 10. The desired damping effect is achieved by a relative movement (damper movement V) between the piston 12 and the damper tube 10 and the associated displacement of the damping medium.

[0033] The piston rod 11 and, in part, the damper tube 10 are protected by the aforementioned protective tube 15. The piston rod 11 is attached at its upper end to an upper damper bearing 13a. The attachment point is covered with a protective cap 14.

[0034] Furthermore, the protective tube 15 is fixed at its upper end to the upper damper bearing 13a by means of a ring-shaped locking element 2a. The protective tube 15 is at least long enough to protect the upper region of the damper tube 10 even when the vehicle shock absorber 1 is not compressed. The damper tube 10, in turn, is connected at its lower end to a lower damper bearing 13b.

[0035] In a known manner, when using the motor vehicle shock absorber 1, the upper damper bearing 13a is connected to the body and the lower damper bearing 13b to the rear axle of a motor vehicle.

[0036] A cover cap 18 (buffer cap) is fitted onto the damper tube 10. The cover cap 18 serves to prevent damage to the sealed inlet area of ​​the piston rod 11 into the damper tube 10. The cover cap 18 (like the protective tube 15) is preferably made of plastic.

[0037] The cover cap 18 is integrally connected to a cage-like extension 18a, which extends towards the lower end of the protective tube 15. The extension 18a extends radially between the protective tube 15 and the damper tube 10. It serves to prevent the painted surface of the damper tube 10 from being damaged by relative movements between the protective tube 15 and the damper tube 10. In a deviation from the exemplary embodiment, the extension 18a can also be longer or shorter, for example, protruding downwards from the protective tube 15.

[0038] In Fig. Figure 2 shows the protective tube 15 in isolation. It has an upper end 19 and a lower end 20. Bellows-like protrusions 15b allow slight compensating movements of the protective tube 15 during a cardanic deflection movement of the vehicle shock absorber 1 during its compression / rebound. The protective tube 15 must also be able to follow this movement. A mounting groove 15a serves to receive the aforementioned locking element 2a.

[0039] From the upper end 19, three slots 15c, evenly distributed around the circumference, also extend a short distance downwards towards the lower end 20 (only one slot 15c is visible in the selected illustration).

[0040] From the Fig. Figure 3 shows a commercially available heat shrink tube 2. The heat shrink tube 2 is made of thermoplastic material and has the property of shrinking rapidly under the influence of heat. The dimensions of the heat shrink tube 2 are preferably selected such that the heat shrink tube 2 can be easily positioned around or concentrically to the mounting groove 15a without exhibiting excessive play relative to the protective tube 15.

[0041] The production of the assembly connection M (see above). Fig. 1) is now achieved by the protective tube 15 ( Fig. 2) is first pushed onto the vehicle shock absorber 1, in particular onto the upper shock absorber bearing 13a, starting from the end of the lower damper bearing 13b. The slots 15c facilitate this sliding.

[0042] The ring-shaped locking element 2a, cut from the shrink tubing 2 (see below), is then attached. Fig.3) positioned at the level of the mounting groove 15a around the protective tube 15 or concentrically to it. Initially, a small radial distance a remains to a radial outer surface 15d of the mounting groove 15a. Positioning can preferably be carried out with the aid of a device.

[0043] Finally, a ring-shaped device 3 is positioned around the ring-shaped locking element 2a at the level of the mounting groove 15a. The device 3 can also serve to position the locking element 2a. It has an annular channel 32. Hot air L enters the channel 32 via a central inlet opening 30. The hot air L flows through the channel 32 and exits radially towards the ring-shaped locking element 2a via outlet openings 31, which are arranged at regular intervals along the inner diameter of the channel 32 (see airflow arrows).

[0044] This results in particularly rapid and reliable heating of the locking element 2a. Due to its material properties, it contracts and clamps tightly around the protective tube 15. In this way, the protective tube 15 is pressed firmly against the upper damper bearing 13a in the area of ​​the mounting groove 15a and thus secured against slipping on the vehicle shock absorber 1.

Claims

[1] Method for producing an assembly (M) consisting of a motor vehicle shock absorber (1) and a protective tube (15) that at least partially surrounds it, wherein the protective tube (15) is first pushed over the motor vehicle shock absorber (1) and then secured against slipping off the motor vehicle shock absorber (1), wherein, to produce the assembly (M), the protective tube (15) is first pushed onto an upper damper bearing (13a) of the motor vehicle shock absorber (1) from the end of a lower damper bearing (13b). characterized by, that the protective tube (15) is secured by an annular locking element (2a) which is positioned around the protective tube (15) and heated, such that the locking element (2a) contracts, clamps around the protective tube (15) and fixes the protective tube (15) at its upper end to the upper damper bearing (13a), wherein a similarly annular device (3) is arranged around the annular locking element (2a) at the level of the mounting groove (15a) for positioning the locking element (2a), which has an annular channel (32) with a central inlet opening (30) and with outlet openings (31) which are arranged at equal intervals along the inner diameter of the channel (32). [2] Method according to claim 1, characterized by , that the ring-shaped locking element (2a) is heated by exposure to hot air (L). [3] Method according to claim 2, characterized by, that the application of hot air (L) takes place at least along a large part of the circumference of the ring-shaped safety element (2a). [4] Method according to claim 2 or 3, characterized by , that the application of hot air (L) is carried out by radially flowing hot air (L) onto the ring-shaped safety element (2a). [5] Method according to any one of the preceding claims, characterized by , that the supply of hot air (L) is focused solely on the ring-shaped safety element (2a). [6] Method according to any one of the preceding claims, characterized by , that the ring-shaped locking element (2a) is a shrink tube (2) made of thermoplastic material or at least a part thereof which has the property of shrinking rapidly under the influence of heat. [7] Assembly (M) consisting of a motor vehicle shock absorber (1) and a protective tube (15) which at least partially surrounds it, manufactured by a method according to one of claims 1 to 6.

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