Method for making a drive line slip joint assembly and component

Method for manufacturing drive shaft sliding joint assembly and component

The present invention generally relates to a drive shaft torsion coupling, or a sliding joint matched with the drive shaft to provide a non-rotatable connection of the sleeved element, so as to transmit rotational force or torque. The present invention particularly relates to a sliding joint assembly of a drive shaft, which uses a male element with a bolt groove to slidably fit into a female element with an inner hole of the bolt groove.

The drive shaft system is used in vehicles or other machines that often need to connect two rotating, usually coaxial or in-line drive spindles to transmit torque from one assembly to the other assembly. The connection itself is a non-rotatable connection, so that when one of the two shafts rotates, the other shaft rotates. Such a connection is typically a slidable connection in the vehicle, and is not limited to the assembly in the vehicle. At the same time, the slidable connection also allows some relative movement in the axial direction, so as to absorb shock during normal operation of the vehicle and absorb energy during a collision of the vehicle. Because one drive shaft, the reference is a yoke shaft, is inserted into the inner hole that engages another drive shaft, and the reference is a sliding yoke, so the drive shaft is connected to a sliding joint. A bolt groove is provided on the outer side of the yoke shaft (male drive member), which corresponds to the bolt groove located in the inner hole of the sliding yoke (female drive member) and engages with each other. The male and female bolt groove assemblies are mutually meshed so that a torsion force can be applied from one drive shaft to the other drive shaft.

The drive shaft sliding connection is used in the steering assembly of the vehicle to transmit the torque from the steering wheel to the tire or the steerable element of the vehicle. Other uses include power removal and different types of rotating vehicle parts such as the rear wheel drive shaft of a rear-wheel drive vehicle. In order to provide a non-rotatable connection, the bolt groove on the yoke shaft must exactly complement the bolt groove on the sliding yoke. However, the two vehicles must be able to move freely in the longitudinal or axial direction relative to each other. In order to facilitate relative axial movement, a low-friction coating such as a nylon coating is applied to one or both of the male or female bolt grooves. The low-friction coating can still allow relative axial movement between the yoke shaft and the sliding yoke with a very close fit or tight tolerance between the yoke shaft and the sliding yoke.

One method for providing a low-friction coating of the pin groove of the yoke shaft is to immerse the pin groove in a molten low-friction coating pool to fill the pin groove. In other words, the yoke pin groove can be coated by heating the pin groove and immersing it in a fluidized bed of the required special form of low-friction coating. At the same time, the slot can be electrostatically coated with a low-friction coating in a special form. We also understand that the low friction coating can be achieved by injection moulding between the combined male and female parts.

There is a problem in most sliding joint connections. When the torque is transmitted from one drive shaft to the other shaft, a tolerance or gap is required between the intermeshing parts so that the male and female parts can slide axially with each other. Will cause some clearance or swing. The looseness in the direction of rotation, that is, one drive shaft can rotate slightly with respect to the other drive shaft, is the so-called backlash. The looseness in the axial direction of the drive shaft or the longitudinal direction of the cantilever is the so-called transverse crack zone. In the past, attempts to solve the tooth gap and transverse crack zone were not completely successful. Like the method disclosed by Beckman et al. in US Patent No. 4,552,544, the radially outward surface of most of the male bolts is machined or broached, while leaving a ridge or unbroached part, which is still convex as an elastic Front protruding edge. The leading edge tightens the radial slack between the two drive shafts. Unfortunately, broaching is expensive and time-consuming, and requires precise adjustment and long-lasting sharpness of broaching tools.

Another method to solve the tooth gap and the transverse crack zone is to use plastic or adhesive material to inject a mold to fill the gap between the meshing square bolts of the sliding joint assembly of the drive shaft. This method is difficult to control, but because this processing requires extreme heating, it is also difficult to achieve. Here, an improved method is needed to produce a low-friction coating, which can make the yoke shaft easy to move axially with respect to the sliding yoke, and at the same time remove the tooth gap and the transverse crack zone in the sliding contact assembly.

The present invention relates to a method for coating a low-friction coating on the component parts of a sliding joint assembly, so as to practically eliminate the problems of tooth gap and transverse crack zone. Coat the yoke shaft or sliding yoke of the sliding joint assembly with a low-friction coating. The yoke shaft and the sliding yoke are heated to a temperature sufficient to soften the low-friction coating, and the yoke shaft is inserted into the inner hole of the sliding yoke. The heat of the yoke shaft and the sliding yoke causes the flow of the low-friction coating to coincide with the gap between the yoke shaft and the sliding yoke square bolt. The yoke shaft is then removed from the sliding yoke, allowing the low-friction coating to cool.

The method of the present invention is particularly applicable to a drive shaft sliding joint assembly having a sliding yoke and a yoke shaft, and the yoke shaft is sleeved through the inner hole at one end of the sliding yoke to engage. The yoke shaft has an outer bolt groove portion with a bolt groove extending radially outward from a central axis, and the sliding yoke has an inner bolt groove with a bolt groove extending radially from the outside to the inside. The low-friction coating applied on the yoke shaft is melted under the heating of the yoke shaft to form a liquid layer on the surface of the outer plug groove portion of the yoke shaft. The liquid silicone release agent causes the yoke shaft to cool slightly, causing the surface of the liquid low-friction coating on the yoke shaft to harden or cover like skin.

In a specific embodiment of the present invention, the low-friction coating is coated on the bolt groove of the yoke shaft. Preferably, a lubricant is coated on the yoke shaft to facilitate the release of the low-friction coating from the sliding yoke. The thermal expansion coefficient of the low-friction coating is preferably larger than that of both the yoke shaft and the sliding yoke, so that the low-friction coating will shrink more than the yoke shaft and the sliding yoke when cooled, so that the coating bolt on the yoke shaft A gap is formed between the groove and the bolt groove of the sliding yoke.

According to the present invention, a drive shaft sliding joint assembly including a sliding yoke and a yoke shaft is also provided. The yoke shaft is sleeved through an inner hole at one end of the sliding yoke to engage, wherein the yoke shaft has a low-friction coating on the yoke shaft groove. The selected area of the thickening of the low-friction coating formed by the portion of the low-friction coating provides a way to enhance the dynamic balance of the drive shaft sliding joint assembly.

<p>(10)Sliding joint assembly</p><p>(12)Yoke</p><p>(14)Sliding yoke</p><p>(16)Central axis</p><p>(18)Inner hole</p><p>(20)Outer bolt groove part</p><p>(22)Male shaft part</p><p>(24)Yoke shaft bolt groove</p><p>(26)Slide yoke bolt groove</p><p>(28)Internal bolt groove part</p><p>(30)Low friction coating</p><p>(32)Concavity</p><p>(34)Slotted surface</p><p>(36)Spine</p><p>(38)Side</p><p>(40)Wedge</p><p>(42)Small agglomeration</p><p>(44)Sag</p><p>(46)Mould</p><p>(48)Die hole</p><p>(50)Mould bolt groove</p>

Figure 1 is a perspective view of a sliding joint assembly manufactured according to the method of the present invention.

Fig. 2 is a perspective enlarged schematic view taken along the line 2-2 of Fig. 1, showing some details of the bolt groove on the yoke shaft.

Figure 3 is a front view of the yoke shaft along line 3-3 in Figure 1, showing that the low-friction coating is mechanically disturbed to cause an increase in the thickness of the selected area.

Fig. 4 shows a schematic perspective view of a mold that is used instead of a sliding yoke to cast a low-friction coating according to the method of the present invention.

Referring first to the drawings, FIG. 1 shows a schematic diagram of a drive shaft sliding joint assembly 10 manufactured according to the method of the present invention. The sliding joint assembly 10 usually includes two tubular elements slidably connected to bamboo, a yoke 12 and a sliding yoke 14. The yoke shaft and the sliding yoke are aligned to surround a common shaft, and the central shaft 16 rotates. The sliding yoke 14 has an inner hole 18 at one end thereof, and this hole is suitable for receiving the sleeve fitting of the yoke shaft.

The nesting of the yoke shaft 12 and the sliding yoke 14 makes the sliding joint assembly easier to install on the vehicle, and can move relatively axially between the yoke shaft and the sliding yoke, so as to adapt to the transmission of the vehicle through rough roads. The force of the bottom element. At the same time, the ability of the yoke shaft to move with respect to the sliding yoke can be beneficial to the absorption of energy in the event of a vehicle collision.

The yoke 12 can be any suitable element for transmitting torque or receiving torque from another similar element. The yoke can be made of any material, such as steel or aluminum. The yoke shaft includes an outer bolt groove portion 20, which fits into the inner hole 18 of the sliding yoke 14, and a male shaft portion 22, which constitutes the main body or main section of the yoke shaft. For a typical steel cylindrical drive shaft sliding joint assembly manufactured in accordance with the present invention, the outer bolt groove portion 20 is approximately 4 inches long.

A number of bolt grooves 24 are positioned around the outer bolt groove portion 20 of the yoke shaft 12. The yoke shaft slot extends radially outward from the central shaft 16. In the art, it is known that the sliding joint of the drive shaft uses the bolt groove to transmit the torsion force. The yoke shaft bolt groove 24 is suitable for engaging with the sliding yoke bolt groove 26, and the sliding yoke bolt groove 26 is positioned inside the inner hole 18 along The inner groove portion 28 of the sliding yoke 14 is attached, so that the yoke shaft 12 and the sliding yoke 14 can be in a non-rotatable (between) relationship. The manufacture and operation of the devices described so far are known in the art.

As shown in FIG. 2, the low-friction coating 30 is applied to the yoke pin groove 24. The low-friction coating can be any material, such as a thermoplastic material, which facilitates the sliding of the yoke shaft slot 24 with respect to the sliding yoke slot 26. A preferred low-friction material is Nylon II, which can be obtained from several nylon material suppliers. Although the low-friction coating is only shown on the yoke pin slot, it must be understood that the friction coating can be placed on either the yoke pin slot or the sliding yoke pin slot, or both. The low-friction coating can be applied to the yoke bolt groove in a variety of ways. In general traditional coating processing, the yoke shaft bolt groove 24 and the outer bolt groove portion 20 are sprayed and cleaned to pre-treat the surface. Then the yoke is immersed in a primer. The yoke shaft 12 and the sliding yoke 14 are heated in a furnace to a temperature in the range of approximately 500°F to 550°F. For not Nylon The temperature requirements of II low friction materials may be different. Then the yoke first enters a fluidized bed of low-friction coating in the form of particles, and then into a liquid release agent, such as a silicone resin release agent. Because the yoke is heated to about 500°F or higher, the particulate low-friction coating will melt to form a liquid layer on the surface of the outer groove portion 20 of the yoke 12. The liquid silicone release agent layer causes the yoke shaft to cool slightly, causing the surface of the liquid low-friction coating on the yoke shaft to harden or cover like skin. The primers, low friction coatings and release agents used are well known to those skilled in the art. The yoke shaft 12 is then inserted into the sliding yoke 14 and cooled and removed. Cooling can be by natural convection, that is, exposure to room temperature air. In addition, cooling can be controlled in a controlled manner, such as airflow or sprinkling water. Of course, the yoke shaft and the sliding yoke must be perfectly aligned during the insertion of the yoke shaft into the sliding yoke. The yoke shaft and the sliding yoke must be aligned or centered radially and concentrically.

When the yoke shaft 12 is inserted into the sliding yoke 14, the heat of the sliding yoke will cause a slight remelting of the low-friction coating skin. Any excess nylon coating will be squeezed and redistributed during insertion. The effect on the low-friction coating is similar to an ironing process. The yoke shaft 12 is inserted into the sliding yoke 14 and heated to form a mating pair of the sliding joint assembly of the drive shaft, which together form the sliding joint assembly 10. Before the yoke shaft is inserted into the sliding yoke, the thickness of the low-friction coating will provide an interference fit ranging from about 0.002 to about 0008 inches. In the best case, the thermal expansion coefficient of the low-friction coating will cause it to shrink when it cools. The shrinkage of the low-friction coating can ensure that the gap between the inter-engaging bolt grooves 24 and 26 will not be completely filled, so that the yoke shaft and the sliding yoke can move relative to each other in the axial direction. Ideally, the thermal expansion coefficient of the low-friction coating is larger than that of the yoke shaft and the sliding yoke, so that when cooled, the yoke shaft and the sliding yoke will shrink less than the low-friction coating, which will cause the slot 24 and the gap between the bolt groove 26. Traditionally, the shrinkage of the low-friction coating is about 8 to 10 times the shrinkage of the yoke shaft and sliding yoke. The heating and ironing of the low-friction coating coating process when the yoke is inserted can be slightly controlled by controlling the temperature of the female part, that is, the sliding yoke 14. In particular, the amount of shrinkage of the low-friction coating and the fit of all the yoke shafts into the sliding yoke can be controlled by the relative temperature of the sliding yoke and the yoke shaft.

In an alternative method of applying a low-friction coating, particle spraying and ditch washing the outer groove portion 20 of the yoke 12 is coated with a particulate low-friction coating material that is electrostatically processed at temperature. A proper amount of particulate low-friction material is removed by the male shaft portion 22 of the yoke shaft 12 through any suitable processing, such as sweeping or vacuum suction. Then the yoke shaft and the sliding yoke are heated to a temperature of at least about 500°C, and the groove portion 20 outside the yoke shaft is immersed in a liquid silicone resin bath. The yoke shaft 12 is then inserted into the sliding yoke 14 to be cooled and removed.

In a preferred embodiment of the present invention, there is sufficient moisture in the lubricant and/or in the low-friction coating itself, and when the yoke shaft 12 is inserted into the heated sliding yoke 14, some moisture will Evaporate, causing bubbles. As a result, a plurality of depressions 32 like pits or pits on the surface of the outer bolt groove portion 20 and the bolt groove 24 are formed, as shown in FIG. 2. These depressions are beneficial in that they can provide a reservoir or flow channel for lubricant.

As shown in FIG. 2, the yoke shaft bolt groove 24 has a bolt groove surface 34 radially outward. In a specific embodiment of the present invention, after the yoke shaft 12 is removed from the sliding yoke 14, the plug surface is freely and briefly touched while the low-friction coating 30 is still warm and deformable. Contact with the low-friction coating before cooling, it can be deformed or disturbed to increase the thickness of the low-friction coating, such as the ridge 36, in selected areas. This ridge may be shaped to extend and bolt on one or more bolt grooves 24. The ridge is made of a low-friction coating material and has some elasticity, and can resist the rotation and cantilever movement of the yoke shaft 12 in the sliding yoke 14, thereby reducing or reducing the tooth gap and the transverse crack zone. In other words, the ridge 36 may be positioned on the side surface 38 of the yoke bolt groove 24.

Any device suitable for deforming or disturbing the deformable low-friction coating can be used. One possible device is a plurality of wedge-shaped elements, such as a wedge 40, as shown in FIG. 3. The wedge shape can extend the entire length of the yoke shaft bolt groove 24 along the direction of the central axis. The low-friction coating is deformed by a wedge shape to form a pair of deformed bodies or small agglomerates 42. The two small agglomerates are separated by a wedge-shaped recess 44. The wedge-shaped depression acts like a lubricant flow channel. As shown in Figure 3, the wedges are annularly spaced around the yoke shaft 24, and therefore small agglomerates will be similarly spaced.

Although the preferred method of manufacturing the drive shaft sliding joint assembly is to insert the yoke shaft 12 into the sliding yoke 14, thereby creating a mating pair of the drive shaft sliding joint assembly, a mold or mold can be used instead of the sliding yoke to reduce friction. The coating is formed or ironed. As shown in FIG. 4, the mold 46 includes a mold hole 48 which is somewhat similar to the inner hole 18 of the sliding yoke 14. The mold 46 can be made of any suitable material, such as steel, and can be adapted to have liquid passages, not shown, for temperature control. The die hole 48 may suitably have a die bolt groove 50 similar to the sliding yoke bolt groove 26. The operation of coating and ironing process when using the mold is similar to the process of using the sliding yoke described above.

During operation, either the yoke shaft 12 or the sliding yoke 14 of the sliding joint assembly 10 is coated with the low-friction coating 30. The yoke sliding yoke is heated to a temperature sufficient to soften or melt the low-friction coating so as to form a liquid layer on the surface of either the outer groove portion 20 of the yoke 12 or the sliding yoke groove 26. The liquid silicone resin release agent is coated on the coated part with the low-friction coating, which can be sprayed or immersed, which causes the coating part to cool slightly, and causes the liquid low-friction coating on the coating part to harden Or heal like skin. The yoke shaft is inserted into the inner hole 18 of the sliding yoke. The heat of the yoke shaft and the sliding yoke causes the flow of the low-friction coating and adapts to the gap between the yoke shaft slot 24 and the sliding yoke slot 26. The yoke shaft is removed from the sliding yoke, and the low-friction coating is allowed to cool. When assembled together, the yoke shaft 12 and the sliding yoke 14 form a mating pair of the drive shaft sliding joint assembly assembly, and the inter-engaging bolt grooves 24 and 26 are easily moved in axially related sleeves and are transmitted by one of the components at the same time. Torque to another component without backlash and transverse crack zone phenomenon.

It is obvious from the foregoing that different types of modifications can be made to the present invention. However, this is considered to be within the scope of the present invention.