WO1999052739A1

WO1999052739A1 - A telescoping device

Info

Publication number: WO1999052739A1
Application number: PCT/SE1999/000558
Authority: WO
Inventors: Åke ASPLUND
Original assignee: Asplund Aake
Priority date: 1998-04-08
Filing date: 1999-04-06
Publication date: 1999-10-21
Also published as: SE9801281L; CA2327250A1; SE511898C2; SE9801281D0; NO20005029D0; AU4065899A

Abstract

A telescoping device in the form of a support pillar for a load vehicle such as a timber carrying vehicle consists of a tube-formed base part (11), a tube-formed intermediate part (12) telescopically carried by the base part, and a top part (13) telescopically carried by the intermediate part. The base part (11) has a threaded rod (15) that is rotatable by a motor (20). When the rod (15) is rotated, a housing (14) that is guided in the base part (11) and carries a nut (30) moves up along the rod (15) when the nut is locked in the housing (14) against rotation. The housing (14) is part of and carries the intermediate part (12). When the intermediate part (12) is extended and the motor rotation is reversed, the nut (30) will rotate with the rod (15) and rotate a second thereaded rod (16) via a gear wheel transmission (31, 32). The rod (16) is carried by the housing (14) and when rotating, it extends the outer part (13) of the pillar. Both extension and withdrawal of the pillar are controlled in steps and in sequence by the repeated reversal of the motor rotation.

Description

1 A telescoping device

This invention relates to a telescoping device.

Such a device can for example be used as a support pillar for a load platform of a vehicle and such a vehicle can for example be a vehicle for carrying timber. When the timber is lifted on and off the vehicle, the operator will loose time if the height of the support pillars cannot be varied and there will also be a risk that he hits the pillars with the crane and destroys them if they are much higher than the actual load. Thus, it is advantageous if the height of the pillars can be adjusted to the actual height of the load both during the loading and unloading. Two part telescoping support pillars are known in the prior art but robust power actuated three part support pillars of this kind are not available on the market.

It is an object of the invention to provide for a simple, robust, reliable, and easily manoeuvrable telescoping device that has three or more telescoping parts. In particular, the invention relates to telescoping devices of this kind which are load supporting pillars for load vehicles, for example vehicles for carrying timber.

The invention will be described with reference to the accompanying drawings that show a preferred embodiment of the invention and a modified design of some parts of the same.

Figure 1 shows in a longitudinal section a telescoping support pillar in its withdrawn position.

Figure 2 shows the same support pillar in a partly extended position.

Figure 3 shows the same support pillar in a fully extended position.

Figures 4-6 show in perspective views various details of the device shown in figures 1-3.

Figure 7 is another view partly in section of some elements.

Figures 8 and 9 are schematic sections that show some elements in various positions

Figures 1-3 show in various positions and in section a support pillar for a load vehicle, for example a vehicle for carrying timber. The pillar has a lower tube formed base part 11, a tubular intermediate part 12 and a tube formed upper (longitudinally outer) part 13. Figure 1 shows the pillar fully withdrawn, that is. the two parts 12,13 are telescopically withdrawn. Figure 2 show 2 the intermediate part 12 extended. Figure 3 show the intermediate part 12 extended and also the upper part 13 extended out of the intermediate portion 12. The intermediate part 12 is mounted on a housing 14 that is carried by a rotatable threaded rod 15 and it is guided in the base part 11. The housing 14 carries a rotatable threaded rod 16 and the rod 16 carries a carrier 17 on which the upper tube formed part 13 is mounted. The carrier 17 is guided in the intermediate part 12. A guiding tube 18 is also mounted on the carrier and it extends outside the rod 15 and guides the rod. The lower part 11 of the pillar is mounted on a plate 19. The rod 15 is mounted on the plate 19 which by the mounting makes the rod rotatable. The plate 19 is to be mounted on the chassis or on the load platform of the vehicle. A motor 20 is mounted on the plate 19 and coupled to rotate the rod 15 through a chain transmission 21.

Figure 4 shows, like figure 1 but on a larger scale, the base part 11 of the pillar in its withdrawn position and it shows some elements that are not illustrated in figures 1-3. The motor 20 is tumable and a spring 25 forces it into a normal position. If the motor turns in either direction from its normal position against the spring force, a cam 22 will actuate a switch 23 to switch off the current to the motor. In this way, the stress on the motor and on all the other elements of the pillar will be reduced. The torque can alternatively be sensed in another way; the current can for example be sensed and the current can be switched off when it reaches a predetermined level. A nut 30 in the housing 14 is journaled in the housing and in engagement with the threads of the rod 15. The nut 30 has an outer gear rim 31 in direct engagement with a gear rim 32 on the rod 16. Thus, these two gear rims 31,32 form a transmission. The rod 15 has a screw 33 screwed into it from the side and the housing 14 has a shoulder 34. The head of the screw 33 stopping against the shoulder 34 defines the lower end position of the housing 14. In this way, a rotation stop is defined. If the housing instead should move against an axial stop, the threaded connection could jam so that the motor would not be able to turn the rod 15 loose again.

The carrier 17 has a sleeve-like portion 35 with an interior thread in engagement with the rod 16. The rod 16 carries a screw 36 and the carrier 17 has a shoulder 37. The screw 36 and the shoulder 37 form together a rotation stop that defines the lower end position of the carrier 17 on the rod 16. If the motor 20 now begins to rotate the rod 15 in the direction indicated by the arrow 38, the nut 30 will tend to rotate the rod 16 in the opposite direction because of the friction in the threads but the stop 36,37 will prevent such rotation and, instead of rotating, the nut 30 will 3 move upwards on the rod 15 and bring the housing 14 with it since it is mounted in the housing. Thus, the intermediate part 12 will extend towards its position in figure 2.

Figure 5 illustrates a position in which the housing 14 is almost in its uppermost position. The carrier 17 is shown in its uppermost position on the rod 16. The upper portion of the rod 15 has a slot 41 in which a catching plate 42 is pivotably mounted on a horizontal screw 43 and protrudes radially out of the slot. The rear end of the catcher 42 carries a projecting spring 44. The nut 30 has an axial projection 45 that has one straight edge and one bevelled edge. When the rod 15 is rotated as described with reference to figure 4, the catcher 42 will engage with the bevelled surface of the projection 45 and the bevelled surface will lift the catcher 42 so that it passes the projection. The nut continues to rise and the rotation of the rod 15 stops when the head of the screw 43 engages with the bevelled surface of the projection 45. This stop position is the same position as is shown in figure 6. The head of the screw 43 cannot be seen in figure 5 since it is at the back of the rod 15.

Then, when the motor is reversed so that it rotates the rod 15 as indicated by the arrow 46 in figure 5, the straight side of the projection 45 on the nut 30 will engage with the catcher 42 so that the nut 30 will rotate with the rod 15 and also rotate the rod 16 in the opposite direction indicated by the arrow 47. The rotation of the rod 16 makes the carrier 17 rise on the rod 16. The carrier 17 has an axial projection 50 and the rod 16 has a screw 51 with a head so that the projection 50 and screw 51 form a rotation stop for the rod 16 and this rotation stop defines the upper limit for the axial movement of the carrier 17 on the rod 16. In figure 5, the screw 51 is shown just when it is about to reach the projection or shoulder 50. The upper end of the rod has a head of plastic 52 that is slidably guided in the upper part 13.

The telescopic support pillar is now in its fully extended position shown in figure 3.

When the upper part 13 is to be withdrawn, the motor rotation is again reversed so that it again rotates the rod 15 as indicated by the arrow 55 in figure 6. The projecting head of the screw 43 will again engage with the bevelled edge of the projection 45 and make the nut 30 co-rotate with the rod 15. The nut 30 will then rotate the rod 16 in the opposite direction, that is, in the direction indicated by the arrow 56 so that the carrier 17 begins to move downwards on the rod 16. The 4 carrier 17 has a hole 57 that is coaxial with the guiding tube 18 and has the same diameter as the interior diameter of the guiding tube. There is a gap 58 between the carrier 17 and the guiding tube 18. The catcher 42 is down because of its own weight and its spring 44 projects obliquely upwards and projects longer than the radius of the head 59. When the carrier 17 now moves downwards with its bore 57 passing the head 59, the carrier will force the obliquely upwards directed spring 44 downwards so that the spring instead will be directed obliquely downwards and lift the catcher 42 just before the carrier reaches its lowest end position on the rod 16 as is schematically illustrated in figure 8.

The upper part 13 of the support pillar is now fully retracted in the intermediate part 12, but the housing 14 is in its top position on the rod 15; the position in which it is shown in figure 6. When the motor rotation is again reversed so that the rod 15 rotates in the opposite direction to that indicated by the arrow 55 in figure 6, the catcher 42 will be able to pass the projection 45 since it is lifted.

In order to prevent the nut 30 from rotating so that the carrier 17 begins to rise on the rod 16, a spring 60 on the underside of the carrier 17 can be used as shown in figure 8 which shows the underside of the carrier 17. The spring force is now sufficient to prevent rotation of the rod 16 and the nut 30, and the carrier 17 is thereby prevented from moving upwards and ensures that the housing 14 instead moves downwards on the rod 15. Instead of the spring 60, a power-actuated hook can be used that positively hhinders the rod 16 from rotating. The housing 14 will thus move downward on the rod 15 so that the support pillar will be fully retracted again. When the tube 18 moves down over the rod 15, the spring 44 of the catcher 42 will remain downward directed so that it holds the catcher lifted. When the intermediate part 12 of the pillar is then extended again, the catcher 42 will be lifted until its spring 44 is released from the tube 18 and enters the space 58 between the guiding tube 18 and the carrier 17 so that the catcher 42 falls down by its own weight and is maintained in its position by the spring 44 which remains in the hole 57 of the carrier 17 as shown schematically on figure 9. The space 58 between the tube 18 and the carrier 17 is thus important since it makes the catcher return to its catching position so that it can function as already described with reference to figure 5. 5 As can be understood from the description above, a telescoping device is provided which is controlled solely by the repeated reversal of the motor rotation. When the operator initiates a withdrawal or extension by starting the motor, the operation is carried out in a predetermined step and it stops automatically when the step is completed. The control is simple because the two threaded rods 15,16 rotate in opposite directions (because the two gear wheels 31,32 are coupled in direct engagement). The operator only selects the direction of the rotation and starts the rotation. To have a chain transmission between the two gear wheels 31,32 and the two rods 15,16 threaded in opposite directions would be an equivalent solution. Alternatively, a chain transmission and threads in the same direction would also be possible.

The telescoping device as illustrated is extensible in two steps. A three-step extension can be achieved if the carrier 17 is replaced by a housing of the same kind as the housing 14. It would be possible to add further steps too.

Claims

1. A telescoping device comprising at least a base part (11), an intermediate part (12) telescopically arranged in the base part and an outer part (13) telescopically arranged in the intermediate part, the base part (11) comprising a threaded first rod (15) that is coupled to be rotated by a motor (20), the intermediate part (12) comprising a housing (14), that contains a first nut (30) rotatable in the housing (14) and in threaded engagement with the first rod (15) so as to be carried by the rod and a rotatable second threaded rod (16) carried by the housing (14) and through a transmission coupled to the first nut (30), and a second nut (17) is in engagement with said second rod (169 and carries said outer part (1) of the telescoping device, characterised in that said transmission (31,32) is so arranged that the housing (14) tends to move upwards on the first rod (15) and the carrier (17) tends to move downwards on the second rod (16) when the first rod (15) is rotated in one direction, first means (42,45) is arranged to lock the first nut (30) on the first rod (15) when the first rod (15) is rotated in the other direction and the housing (14) is in a top position on the first rod, and second means (57) is arranged to release the first nut (30) from said first means (42) when the outer part (13) of the telescoping device nears its bottom position in the intermediate part (12).

2. A telescoping device according to claim 1, characterised in that said second rod (16) is rotatable in the housing (14) and the transmission (31,32) between the first nut (30) and the second rod (16) is arranged to make them rotate in opposite directions.

3. A telescoping device according to claim 2, characterised in that the first nut (30) and the second rod (16) are in direct engagement.

4. A telescoping device according to any one of the preceding claims, characterised in that an upper limit for the first nut (30) on the first rod (15) is a rotation stop (43.45). 7

5. A telescoping device according to any one of the preceding claims, characterised in that said first means (42,45) is formed by an axial projection (45) on the first nut (30) for engagement with a radial projection (42) on the first rod (15).

6. A telescoping device according to claim 5, characterised in that said radial projection (45) is a pivotable catcher (42) arranged to be lifted into an idle position by said axial projection (45) on the first nut (30) before the nut reaches an upper limit stop (43,45) on the first rod (15) and arranged to be returned to its working position when the axial projection (45) has passed it so that it will hinder the first nut (30) from rotating downwards on the first rod (15), and said second means (17,57) is coupled to the outer part (13) of the telescoping device and arranged to lift the catcher (42) when the outer part (13) of the telescoping device nears its bottom limit position in the intermediate part (12).

7. A telescoping device according to claim 6, characterised in that the first rod (15) has a slot (41) in which the catcher is arranged so that it protrudes out of one side of the slot and protrudes with a control element (44) out of the other side of the slot, and said second means (17,57) is arranged to lift the catcher (42) by forcing down said control element (44).

8. A telescoping device according to claim 1, characterised in that its outer part (13) has a guiding tube (18) for guiding the first rod (15), and an element (17) with a hole (57) that is coaxial with the guiding tube and defines said second means by means of its edge, a space (58) between the tube (18) and said edge (57) permits the catcher (42) to switch position.

9. A telescoping device according to any one of the preceding claims, characterised by means (22,23,25) for sensing the motor torque and initiating a motor shut-off when the torque reaches a predetermined level.

10. A telescoping device according to claim 9,characterised in that the motor (20) is mounted to be resiliently turnable in both directions from a normal working position.

11. The use of a telescoping device according to any one of the preceding claims as a support pillar on a load vehicle, in particular a vehicle for carrying timber.