WO1989011437A1

WO1989011437A1 - Lifting device for use e.g. in conjunction with an automobile body straightener

Info

Publication number: WO1989011437A1
Application number: PCT/FI1989/000089
Authority: WO
Inventors: Toivo Mäkelä
Original assignee: Maekelae Toivo
Priority date: 1988-05-19
Filing date: 1989-05-18
Publication date: 1989-11-30
Also published as: FI882366A0; FI85827B; FI85827C; AU3683189A; FI882366A

Abstract

Lifting device for use e.g. in conjunction with an automobile body straightener, said lifting device comprising at least one power means (1) and at least one lifting means. The lifting means (2) and the power means are linked to the frame (8) of the straightener in such manner that the joint (3) connecting the lifting means to the frame is closer to the second end (5) of the lifting means than to its first end (4), and that the first end (6) of the power means is linked to the second end of the lifting means while the second end (7) of the power means is linked to the frame (8) of the straightener.

Description

LIFTING DEVICE FOR USE E.G. IN CONJUNCTION WITH AN AUTO¬ MOBILE BODY STRAIGHTENER

The present invention relates to a lifting device for use e.g. in conjunction with an automobile body straightener, said lifting device comprising at least one power means and least one lif ing means.

Among the previously known lifting devices designed for use in conjunction with an automobile body straightener there are e.g. devices which, because of their height, have to be mounted in a pit below the level of the garage floor to enable an automobile to be brought onto the device. This is a very expensive solution and has the additional drawback that the device, being built in the floor, is fixed in one place. As an example representing the state of the art, reference is also made to Finnish patent nr. 53930, which proposes a detached lifting unit movable on wheels and with a straightening bench attached to it. When a vehicle is being driven onto the unit, the straightening bench is in an inclined position, and it has separate track plates to enable the vehicle to be brought onto the bench and secured in place. Once the vehicle has advanced far enough, the bench is turned to the horizontal position, the track plates standing in the way are removed and the necessary safety bars are locked in place to prevent the straight¬ ening bench from being tilted. The disadvantages of such a device are complexity of construction and the consequent high cost. Moreover, the device is clumsy in practical use because it requires a large number of various operations and safety measures before the actual straightening work can be started.

The object of the present invention is to eliminate the drawbacks observed in the aforementioned solutions and to achieve an easy-to-use, reliable and low-cost lifting device for use in conjunction with an automobile body straightener. The lifting device of the invention is characterized in that a lifting means and a power means are turnably linked to the frame of the automobile body straightener in such manner that the joint coupling the lifting means to the frame is closer to the second end of the lifting means than to its first end, and that the first end of the power means is linked to the second end of the lifting means while the second end of the power means is linked to the frame of the straightener. The advantages of the device are a compact construction and the fact that the lifting device and its actuating means are protected by the frame of the straightener as they are placed inside it.

A preferred embodiment of the invention is characterized it that the lifting means consists of at least two lifting legs placed at a distance from each other, at least one bracing bar connecting the legs, and bearing rollers and at least one lug for the mounting of the power means. The advantages are an even distribution of lifting power in the device and the fact that sliding friction is converted by the bearing rollers into rolling friction during the lifting.

Another preferred embodiment of the invention is character¬ ized in that the lifting leg as seen from above is a plate¬ like body of essentially even thickness and, as seen from the side, a body of a width that increases steadily from the first end towards the second end, the width being largest at the level of a bend in the contour of the leg. This construction provides the considerable advantage that the lifting operation can be performed in two phases. The lifting power needed in the preliminary lifting phase has been reduced by shortening the lever arm of the lifting leg so that the lever arm extends from the bend, which rests on the floor, to the joint on which the leg turns. However, a larger lifting height is required than is possible to achieve in this manner. In the second phase, therefore, when the power means has turned into a more favourable angle, the end of the lifting leg hits the floor. As a result, the length of the lever arm increases and more power is needed. Correspondingly, a larger lifting height is achieved.

A third preferred embodiment of the invention is character¬ ized in that the second end of the lifting means is provid¬ ed with two mounting lugs for each power means, said lugs having a hole for linking the power means to the lifting means in such manner that the pivot of the power means joint is located vertically as far as possible from the pivot of the joint of the lifting means, and that the relative positions of said pivots and of the pivot of the joint at the second end of the power means are so chosen that the moment arm of the thrust motion of the power means relative to the joint of the lifting means increases after the initial phase of the lifting operation. This arrange¬ ment provides the advangtage that several smaller power means can be used. By maximizing the vertical distance between the pivots, the lever arm of the power means rela¬ tive to the joint of the lifting means also becomes as long as possible in the initial stage of the lifting operation, and by virtue of correct dimensioning of the parts between the joints, the length of the lever arm increases as the lifting process advances and more power is needed.

A further preferred embodiment of the invention is charac¬ terized in that the straightener is provided with two lifting devices placed symmetrically relative to each other and in a mirror-image configuration relative to the trans¬ verse axis of the straightener frame and in such manner that when the power means applies a thrust to the lugs of the lifting means, the bearing rollers at the bends of the lifting legs are the first to hit the base, e.g. floor, and after further application of thrust the bearing rollers at the first end of the leg hit the floor, so that, as the lifting means is further turned about its joint, the rollers at the bend are lifted clear of the floor. The advantages are a minimized power requirement and a compact construction. The construction is such that the lifting operation can be divided into a preliminary phase and a main lifting phase in such manner that the available lifting power is optimized.

The invention is described in the following by the aid of an example with reference to the drwings attached, wherein

Fig. 1 presents the frame of an automobile body straight¬ ener in top view, showing also the lifting devices mounted in the frame in top view.

Fig. 1 presents a lateral view of the frame of an automobile body straightener in the low position and sectioned along line A-A in Fig.1.

Fig. 3 presents a lateral view of the frame of an automobile body straightener at the final stage of the preliminary lifting operation and sectioned along line A-A in Fig. 1.

Fig. 4 presents a lateral view of the frame of an automobile body straightener in the high position and sectioned along line A-A in Fig. 1.

The frame 8 of the automobile body straightener consists of square-section beams welded together so as to form a rect¬ angular frame. The frame 8 is provided with transverse beams 17 which reinforce the frame and serve as a mounting base for the lifting devices. The transverse beams are placed symmetrically on either side of the centre of the frame relative to the longitudinal direction of the frame. Each reinforcing beam 17 is provided with four mounting lugs 18, which serve to link the second ends 7 of the hydraulic cylinders used as power means 1 to the beams 17. The frame of the automobile body straightener 8 is provided with two symmetrical lifting devices operating in opposite directions, each device consisting of a power means 1 and a lifting means 2. Each lifting means 2 consists of a pair of parallel legs 9 placed at a distance from each other, a transverse bracing bar 10 connecting the legs, another bracing bar 19 of a lighter construction, bearing rollers 11 and 12 and lugs 13. Seen from above, the leg 9 is a plate-like body of even thickness. In lateral view, the upper edge of the leg 9 is straight and has a length equal to the total length of the leg. The second end of the leg is perpendicular to the upper edge, and the portion of the lower edge between the second end and a bend 14 is parallel to the upper edge, while the portion of the lower edge between the bend 14 and the first end of the leg rises steadily towards the upper edge. One end of the leg is attached to the bracing bar 10 at a point close to the end of the bar 10, which is linked by a joint 3 to the frame 8 of the straightener. Close to each end of the bracing bar 10, on the side opposite to the legs 9, there is a lug 13 for the joint that connects the first end 6 of a power means 1 to the lifting means. The pivot 15 of the joint at the first end 6 of the power means 1 is located as high up as possible, whereas the pivot of the joint supporting the second end 7 is located as low down as possible, so that the power means is in an inclined position. Also, the pivot 3 of the joint of the lifting means is located as low down as possible to ensure that the lever arm acting between the pivots 3 and 15 is as long as possible so as to reduce the lifting power required. Thanks to the geometry of the lug 13, the relative positions of pivots 3 and 15 and the pivot of the second end 7 of the power means are such that, relative to the joint 3 of the lifting means, the moment arm acting during the thrust motion of the power means increases after the initial stage of the motion. In addi¬ tion, the leg 9 is provided with a bearing roller 11 at the first end and another roller 12 at the bend 14 of the leg. The bearing rollers are mounted with bearings on the inside of the legs and their function is to convert sliding fric¬ tion into rolling friction during the lifting. Especially the roller 11 at the end of the leg moves through a f irly long distance during the main lifting phase after the preliminary phase. The bearing rollers are needed in the first place because there are two lifting devices acting in opposite horizontal directions. The lighter bracing bar 19 between the legs is placed close to the first end 4, where it adequately reinforces the narrower ends of the legs.

Due to the geometry of the device, a much larger lifting power is needed at the initial stage of the lifting opera¬ tion than at its final stage when pivot 15 has moved higher relative to pivot 3 and the moment arm for the power means has grown longer. Since the lifting power is limited, a specific preliminary lifting phase is needed, during which the moment arm of the supporting forces acting against the floor is shortened relative to pivot 3. The geometry of the lifting leg 9 makes this possible. At first, the moment arm of the supporting forces is short, extending from the bearing rollers 12 at the bend 14 of the leg to the joint 3. As the lifting motion continues and the power means 1 exerts a thrust on the lifting means from pivot 15, the bearing rollers 12 rise clear of the floor and the rollers 11 at the ends of the legs begin to bear the load. This means that the moment arm of the supporting forces becomes longer, but at the same time the angle of the power means has also become more favourable and the length of its moment arm between pivots 15 and 3 has increased due to the relative positions of the pivots, so that the lifting operation is possible. To ensure that the lifting operation can be carried out safely, the two lifting devices have to be mutually synchronized so that they operate simultaneous¬ ly, or at least nearly simultaneously. The simplest syn¬ chronization in this solution is achieved by correct dimensioning of the parts. If the hydraulic cylinders and the lifting means, respectively, are of equal dimensions and the same working pressure is present in the cylinders, the lifting devices will operate simultaneously.

It is obvious to a person skilled in the art that the invention is not restricted to the example described above, but that it may instead be varied in the scope of the fol¬ lowing claims. Thus, for instance, the lifting leg may be suitably curved in profile to achieve a more even distri¬ bution of the lifting power. Also, there are many different ways in which the lifting devices can be synchronized.

Claims

1. Lifting device for use e.g. in conjunction with an auto¬ mobile body straightener, said lifting device comprising at least one power means (1) and at least one lifting means, c h a r a c t e r i z e d in that the lifting means (2) and the power means are turnably linked to the frame (8) of the straightener in such manner that the joint (3) con¬ necting the lifting means to the frame is closer to the second end (5) of the lifting means than to its first end (4), and that the first end (6) of the power means is linked to the second end of the lifting means while the second end (7) of the power means is linked to the frame (8) of the straightener.

2. Lifting device according to claim 1, c h a r a c ¬ t e r i z e d it that the lifting means (2) consists of at least two lifting legs (9) placed at a distance from each other, at least one bracing bar (10) connecting the legs, and bearing rollers (11, 12) and at least one lug (13) for the mounting of the power means.

3. Lifting device according to claim 1 or 2, c h a r a c ¬ t e r i z e d it that the lifting leg (9) as seen from above is a plate-like body of essentially even thickness and, as seen from the side, of a width that increases steadily from the first end (4) towards the second end, the width being largest at the level of a bend (14) in the contour of the leg.

4. Lifting device according to claim 1, 2 or 3, c h a r ¬ a c t e r i z e d it that the second end (5) of the lifting means is provided with two mounting lugs (13) for each power means, said lugs having a hole for connecting the power means (1) to the lifting means with a joint (15) in such manner that the pivot (15) of the power means joint is located vertically as far as possible from the pivot (3) of the joint of the lifting means, and that the relative positions of said pivots (3) and (15) and of the pivot of the joint at the other end (7) of the power means are so chosen that the moment arm of the thrust motion of the power means relative to the joint (3) of the lifting means increases after the initial phase of the lifting operation.

5. Lifting device according to any one of the preceding claims, c h a r a c t e r i z e d in that the straight¬ ener is provided with two lifting devices (16) placed symmetrically relative to each other and in a mirror-image configuration relative to the transverse axis of the straightener frame (8) and in such manner that when the power means applies a thrust to the lugs (13) of the lifting means, the bearing rollers (12) at the bends of the lifting legs are the first to touch the base, e.g. floor, and after further application of thrust the bearing rollers (11) at the first end of the leg touch the floor, so that, as the lifting means is further turned about its joint (3), the rollers (12) at the bend are lifted clear of the floor.