The present invention relates to a coupling device according to the preamble of claim 1.

The coupling device according to the invention is preferably intended to be used for coupling a trailer or similar to a motor vehicle, such as a passenger car.

Through the Swedish patent specification 8400369-8 a coupling device of the kind stated by way of introduction is known. This known coupling device has turned out to be safe and reliable in practice. Another similar coupling device is known through EP 0160934.

The object of the present invention is to improve and simplify a coupling device of the kind stated by way of introduction.

This object has been attained in that the coupling device according to the invention has obtained the features stated in claim 1.

The invention will now be described more closely below with reference to the attached drawings, on which

Figure 1 in a side view shows the coupling portion of a first embodiment of the coupling device according to the invention,

Figure 2 shows the coupling portion according to Figure 1 in a view from above,

Figure 3 shows the coupling portion according to Figures 1 and 2 in an end view in the direction of arrows III-III in Figure 1,

Figure 4 shows a section through the same coupling portion in the direction of arrows IV-IV in Figure 2,

Figure 5 in a side view shows an attachment portion associated with the coupling portion according to Figures 1-4,

Figure 6 shows the attachment portion according to Figure 5 in the direction of arrows VI-VI in Figure 5,

Figures 7a-e in sections in the direction of arrows VII-VII in Figure 2 illustrate succesive steps at disconnecting the coupling portion according to Figures 1-4

and -the attachment portion according to Figures 5, 6,

Figures 7e-i in similar sections illustrate succesive steps at connecting together the same coupling portion and attachment portion, Figure 8 in a similar section as in Figure 7 more in detail shows the associated parts when the coupling device takes the same coupling position as in Figures 7a and i,

Figure 9 in a side view shows the mutual position of the coupling portion and the attachment portion in connection with the transfer from step 7d to 7e or the transfer from step 7g to 7h,

Figures 10-12 in side views illustrate three succesive steps at connecting the coupling portion to the attachment portion in a second embodiment of the coupling device according to the invention.

The embodiment of the coupling device according to the invention shown in Figures 1-9 includes an attachment portion generally designated 2. The attachment portion 2 consists of a round bar 4 around the periphery of which a groove 6 extends at a distance, more closely defined below, from the left hand end in Figure 5. To the right of the groove 6 in Figure 5 it is illustrated how the round bar 4 by means of welds, indicated at 8, carries mounting plates 10, by means of which the attachment portion 2 is attached by means of bolts, of which one is indicated at 12, to a rear vehicle beam, indicated in section at 14. Elements 8-14 only serve as examples of illustration of how the attachment portion 2 can be attached to a vehicle, and are of course adapted to the type and kind of the vehicle. The left hand end of the bar 4 in Figure 5 is bevelled at 16. On one of its sides the bar 4 at a distance from the groove 6, defined more closely below, has a hole 18, the shape and depth of which appears from some of the views in Figure 7. A bevel 19 connects to the mouth of the hole 18, as shown in Figures 5 and 7c. On the diametrically opposite side the bar 4 has a plane bevel 20 extending between the bevel 16 and the groove 6 and having the same

depth as the latter..

The coupling device according to the first embodiment also includes a coupling portion generally designated 22. At one of its ends the coupling portion 22 has a coupling ball 24 of a conventional kind which, likewise conventionally, is located on the end of a round bar 26. The round bar 26 is attached, indicated by a weld 28, into the end of a tube 30 intended for receiving the bar 4 when the portions 2 and 22 are to be connected together. At the same distance from the centre of the tube 32 as the centre of the hole 18 is located from the groove 6 in the bar 4, the tube 30 includes an inwardly protruding shoulder 31. More particularly, the shoulder 31 is located in the inside of the tube 30 located closest to the tube 32 and has a depth of penetration corresponding to the depth of the bevel 20 in the bar 4 and a thickness corresponding to the width of the groove 6.

A further tube 32 is attached perpendicularly to the side of the tube 30 and opens into the inner of the tube 30 via said side. In particular referring to Figure 8, the tube 32 serves for guiding a piston generally designated 34. The piston 34 has a piston head 35 with a shape complementary to the shape of the hole 18 in the bar 4. More particularly this shape consists of a short essentially cylindrical end portion 36 and a portion 38 in the form of a frustrum of a cone connecting thereto. The hole 18 has portions corresponding to the portions 36 and 38, the inner cylindrical portion of the hole then being somewhat longer than the corresponding portion 36 of the piston head 34, so that when the piston head 35 is introduced into the hole 18 in a way to be described more closely below, the respective portions in the form of frustrums of cones come into engagement with each other. The outer diameter of the bar 4 and the inner diameter of the tube 30 are so adapted to each other that the bar 4, of a reason to be described more closely below, fits with some play in the tube 30 as indicated at 39 in Figures 7a and 7i, but omitted in the rest of the sub-Figures of Figure 7

for the sake of simplicity.

The piston 34 furthermore in connection with the piston head 35 has a piston slide 40 fitting with slide fit in the bore of the tube 32. The piston slide on its side remote from the piston head 35 has an edge bevel 42 with a function to be described more closely below. At a distance from the piston slide 40 the piston 34 has a further piston slide 44 likwise fitting with slide fit in the bore of the tube 32. To the piston slide 44 a central piston rod 46 connects. The bore of the tube 32 is closed at the end by means of an end lid 48 of which a cylindrical portion 50 is screwed into the end of the tube 32. The lid 48 has a central through hole 52 adapted to the piston rod 46. In the position of the piston 34 shown in Figure 8 with the piston head 35 in engagement with the hole 18 the other end of the piston rod 46 lies essentially in plane with the outside of the lid 48, as shown in Figure 8. By means of a screw spring 54 the piston 34 is biased towards the rod 4. More particularly the screw spring 54 is located around the piston rod 46 acting between the piston slide 44 and the lid 48 in the way shown in Figure 8.

The tube 32 on its underside carries a bearing housing 56 for a shaft 58 having a hexagonal section and extending transversly to the tube 32. More particularly, the shaft 58 is non-rotatably enclosed in a bearing sleeve 60 by means of which the shaft 58 is rotatably journalled in the bearing housing 56. The hexagonal shaft 58 in the diametrical plane of the tube 32 non-rotatably carries a plate shaped abutment element 62 extending into the tube 32 between the piston slides 40 and 44. More particularly this plate shaped abutment element 62 is located in a longitudinally extending slot 64 in the wall of the tube 32 and that also extends down through the bearing housing 56. The shaft 58 by means of a torsion spring 66, surrounding the same, is biased counter-clockwise in the sections shown in Figures 7 and 8. More particularly, the spring 66 acts in the way indicated in Figures 1 and 4 between one of the ends of the shaft 58 at 68 and the

bearing housing 56 at 70. On its other end the shaft 58 carries a handle 72 by means of which the shaft 58 can be rotated against the action of the spring 66.

As appears from Figures 7 and 8 the abutment element 62 in section is constructed roughly as an arm extending from the shaft 58. The end remote from the shaft 58 of this arm has a portion 74, curved in a side view, intended for cooperation with the bevel 42 of the piston slide 40 in a way to be described more closely below in the position shown in Figures 7a, 7i and 8. The curved portion 74 extends between a nose 76 and a notch 78. The function of the last mentioned elements will appear more closely below from the description of the interconnection and disconnection, respectively, of the portions of the coupling device.

In Figure 7a the coupling portion and the attachment portion 2 are shown in an interconnected situation. The piston head 35 penetrates into the hole 18 of the bar 4 and by means of the above mentioned play 39 between the bar 4 and the inside of the tube 32 the bar 4 is pressed into contact, free of play, against the inside of the tube facing the piston 34, by engagament between the curved portion 74 of the abutment element 62 and the bevel 42 on the piston slide 40. More particularly, the engagement between the curved portion 74 and the bevel 42 is wedgelike, which is due to the fact that the radius of the curved shape 74 does not extend through the centre of the shaft 58, but above this in Figure 7a. Disengagement of the coupling portion 22 from the attachment portion 2 begins with rotation of the handle 72, and thereby the shaft 58 and the abutment element 62, against the action of the torsion spring 66, the piston 34 then, when the abutment element 62 has reached the position shown in Figure 72, being also moved by engagement of the abutment element 62 against the piston slide 44. Finally the position shown in Figure 7c is reached, where the edge of the piston slide 44 has been received in the notch 78 in the abutment element 62. The shape of the notch 78 is then

such with respect to the edge of the piston slide 44 that the position shown in Figure 7c implies a mutual catching of the piston 34 and the abutment element 62 under the action of the respective springs 54 and 66. The length of the piston head 35 is so dimensioned that in the same position the end of the piston head extends somewhat into the hole 18 into alignment with the bevel 19.

As shown, in the position shown in Figures 7a-c, the bevel 20 on the bar 4 is furthermore located opposite to the shoulder 31 in the inside of the tube 30, implying that the shoulder 31 engages into the groove 6 in the bar 20 and thereby blocks the bar 20 against longitudinal movement. If now the ball portion 24, 26 by the coupling portion is rotated clockwise, the piston head 35 via the bevel 18 reaches up onto the periphery of the bar 4 which, however, implies further shifting of the piston 34 in the direction from the bar 4 due to the fact that, as mentioned above, in the position 7c the piston head 35 extends somewhat into the hole 18. This further longitudinal shifting of the piston 34 is enough to release the engagement between the notch 78 of the abutment element 62 and the edge of the piston slide 44 implying that the abutment element 62 under the action of the torsion spring 66 rotates anti-clockwise so that the nose 76 on the abutment element 62 engages the backside of the piston slide 40.

When the bar 20, by the rotational movement indicated in Figure 7d by the arrow 80, has reached a position in which the hole 18 is located diametrically opposite to that in Figures 7a-7c, the bevel 20 of the bar 4 at the same time has reached the same side in the tube 30 as the abutment element 31. This implies that the coupling portion 22 without being obstructed by the groove 6 in the bar 4 is drawn from the bar 4. This mutual rotational position of the coupling portion 22 and the attachment element 2 is shown in Figure 9, it being noted that the ball 24 points downwardly. When the coupling portion 22 is entirely free also the piston 34 is free to move under the

action of its biasing spring 54 in the inner of the tube 30. This position is shown in Figure 7e, it being then noted that the abutment 62, although not being in engagament with the piston slide, blocks movement of the piston 34 to the right in Figure 7e. Booth elements 34 and 62 are then biased to the position shown by their respective biasing springs. The handle 72 takes the upwardly pointing position shown in Figures 1-4.

Figure 7e can also serve as a starting point for describing the interconnecting steps for the portions 22 and 2. By turning the handle 72 the piston 34 will be moved from the position shown in Figure 7f by engagement between the abutment element 62 and the piston slide 44 until mutual catching of the piston 34 and the abutment element 62 in the way shown in Figure 7g is attained. With the ball portion 24 pointing downwards as in Figure 9 the coupling portion 22 is now brought onto the bar 4, the end bevel 16 on the bar 4 then initially comming into engagement with the end of the piston head 35 and guiding the latter up onto the periphery of the bar 4, implying that the piston 34 simultanously is subjected to a small overtravel to the right, which is enough to release the engagement between the abutment element 62 and the piston slide 44, as indicated in Figure 7h. With the bar 4 now introduced so far into the tube 30 that the hole 18 and the centre of the tube 32 are in the same plane, the coupling portion 22 is now rotated from the position shown in Figure 9 to the postion shown in Figure 1, in which the hole 18 has been brought just in front of the piston head 35 and thereby the locked position of engagement shown in Figure 7i between the two portions 2 and 22 has been obtained, said position of engagement being the same as in Figure 7a and Figure 8. It should be noted that this locked position has a visible indication in that the end of the piston rod 46 lies essentially in plane with the outside of the lid 48. In all other positions of the piston 34 the end of the piston rod 46 protrudes out through the lid 48.

It should furthermore be noted that in the mutual

interconnecting position of the portions 2 and 22 a threefold security against unintentional release of the joint exists, viz. through the engagement of the abutment element 31 in the groove 6, the engagement of the piston head 35 in the hole 18, and the engagement between the abutment element 62 and the bevel 42 of the piston slide 40.

For the embodiment according to Figures 10-12 the same referens designations are used as for the first embodiment, but with the addition of prime signs. This embodiment differs from the preceding embodiment essentially only in that the bar 4 and the tube 30 with the coupling arrangements thereon have changed place, i.e. the bar 4' is located on the coupling portion 22' and the tube 30' on the attachment portion 2'.

In Figure 10 the beginning of the interconnection of the coupling portion 22' and the attachment portion 2' is indicated by the arrow 84. The counterparts, not shown, of the piston 34 and the abutment element 62 take the same mutual catching position as in Figure 7g. From the inserted position in Figure 11 of the coupling portion 22' rotation according to the arrow 86 to the full interconnecting position shown in Figure 12 is carried through.

The steps shown in Figures 10-12 thus correspond to Figures 7g-i.