AU2008201151B2

AU2008201151B2 - Hydraulically actuated tailgate loader

Info

Publication number: AU2008201151B2
Application number: AU2008201151A
Authority: AU
Inventors: Gisela Weber; Gunter Weber
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-03-30
Filing date: 2008-03-12
Publication date: 2014-02-06
Anticipated expiration: 2028-03-12
Also published as: DE102007015820A1; AU2008201151A1

Abstract

Abstract Hydraulically actuated tailgate loader 5 The invention concerns a hydraulically actuated tailgate loader for a truck, that has at least: one pivotable lifting arm that pivots a platform carrier and is articulately joined to the truck and can be pivoted by at least one single-acting lifting cylinder, 10 one loading platform that is articulately joined to the platform carrier and can be pivoted by a single-acting locking cylinder, and one hydraulic module with a hydraulic pump to supply the at least one lifting cylinder and the at least one locking 15 cylinder with hydraulic fluid, wherein the at least one lifting cylinder and the at least one locking cylinder are charged by the hydraulic module with the same hydraulic pressure, and from a bottom position the at least one lifting cylinder 20 can be actuated at a lower hydraulic pressure than the at least one locking cylinder, by virtue of the piston diameter of the lifting cylinder being markedly greater than the diameter of the locking cylinder. (Fig.4) N.\Melbourne\Cases\Patent\76000-76999\P76955.A\Speci\76955.AUGHSpeci asfiled.doc 12/03/08 eb 4Fig.4

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): Gisela Weber and Gznter Weber Invention Title: Hydraulically actuated tailgate loader The following statement is a full description of this invention, including the best method for performing it known to me/us: P7695S.AU PatSet Filng Appicaton 2008-3-7.doc (M) - 2 Hydraulically actuated tailgate loader The invention concerns a hydraulically actuated tailgate loader for a truck. 5 Hydraulically actuated tailgate loaders are generally fastened in the rear region of a truck on its vehicle structure and can be moved into various positions by means of a hydraulic module. In this conjunction especially a 10 bottom loading and unloading position to accept loads, that subsequently can be lifted from the loading plane, and a top loading and unloading position are provided, in which the loading plane of the tailgate loader forms a horizontal extension of the loading area. Furthermore, 15 generally a vertical transport position of the loading platform at the rear end of the loading area is possible, that can be used for the transport. DE 103 59 078 Al shows a hydraulically actuated tailgate 20 loader of this type, wherein an additional longitudinal distribution of the carrying body, incorporating the lifting arm and the loading platform, is possible on the vehicle structure. Although such tailgate loaders make complex movements and reliable actuating possible, their 25 construction is very complicated, complex and consequently expensive to manufacture. Furthermore, their manipulation could be quite complex. In a first aspect, the invention provides hydraulically 30 actuated tailgate loader for a truck, that has at least: one carrying structure for fastening it on the truck, one pivotable lifting arm that can be articulately joined to the carrying structure, one platform carrier provided on the external end of the lifting arm, at least one lifting 35 cylinder to pivot the lifting arm, one pivotable loading platform to accept the loads that is articulately joined to the platform carrier, 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 3 at least one locking cylinder articulately joined between the platform carrier, and the carrying structure for pivoting the loading platform, and one hydraulic module with a hydraulic pump to supply the 5 least one lifting cylinder and the at least one locking cylinder with hydraulic fluid, wherein: the at least one lifting cylinder and the at least one locking cylinder have a single-acting construction, 10 in the case of a lifting cylinder the lifting arm is in its bottom position and in the case of a relieved locking system the loading platform is in its bottom position, the at lest one lifting cylinder and the at least locking cylinder are connected to a common outlet line system 15 originating from the hydraulic module, and the least one lifting cylinder can be actuated at a lower hydraulic pressure than the at least one locking cylinder. The at least one lifting cylinder and the locking cylinder are connected to the outlet line system without check 20 valves. In an embodiment the at least one lifting cylinder and the at least one locking cylinder are charged with the same hydraulic pressure by the hydraulic module via the outlet 25 line system, preferably a common outlet line. In an embodiment the locking cylinder is connected to the common external outlet line via a throttle. 30 In an embodiment in its top pivoted position the lifting arm is stopped by a stop on the vehicle, e.g. a stop of the platform carrier or of the lifting arm on a rear end of the loading area. 35 In an embodiment when the hydraulic pump is actuated from the bottom loading and unloading position of the loading platform and of the lifting arm in a first movement phase 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 4 first the at least one lifting cylinder is actuated and the lifting arm is pivoted upward until it is stopped by the stop, and subsequently while the pressure is increased by the hydraulic pump in a second movement phase the at 5 least one locking cylinder is actuated and the loading platform is pivoted upwards. In an embodiment in a top, essentially vertical pivoted position, the loading platform can be locked by a 10 mechanical locking, e.g. a locking hook. In an embodiment from a top travelling position with upward folded loading platform a lowering follows, wherein, possibly after releasing the mechanical locking, 15 with a non-actuated motor and open check valve the downward pivoting loading platform presses the hydraulic fluid from the locking cylinder and in the case of an at least partially opened platform and at least partially retracted locking cylinder the locking cylinder the 20 locking pressure exerted by the loading platform falls below the lifting pressure and presses back the hydraulic fluid of the at least one lifting cylinder into the hydraulic tank. 25 In an embodiment two parallel actuated lifting cylinders are provided. In an embodiment the at least one lifting cylinder has a greater piston diameter than the at least one locking 30 cylinder. In an embodiment a valve control system is provided in the hydraulic module, that has: a non-return valve provided between the hydraulic pump and 35 an outlet connector of the hydraulic unit and a pressure-limiting valve provided between the outlet of the hydraulic pump and a hydraulic reservoir. 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 5 In an embodiment the valve control system has a Minimess connector to set the pressure-limiting valve. 5 In an embodiment also described herein the valve control device between its outlet connector and a hydraulic reservoir has a check valve and a volume control valve connected in series. 10 In an embodiment the control valve is pressure compensated. In an embodiment an opening spring, e.g. a torsion spring or a pneumatic spring is provided in the locking cylinder 15 to support the opening operation of the loading platform. In an embodiment the lifting arm, the at least one lifting cylinder and the locking cylinder are articulately joined to a carrying body acting as carrying structure, that is 20 provided for the fastening on the vehicle structure, e.g. on the vehicle frame of the truck. A truck with such a tailgate loader is also provided. 25 The invention is based on the concept of controlling the at least one lifting cylinder and the locking cylinder via a common external hydraulic pressure, in particular a common outlet line and affect their successive movement between the relevant positions by a corresponding design 30 of the single-acting cylinders, in particular by a different design of the piston diameters of the lifting and locking cylinders. In this connection the at least one lifting cylinder 35 (preferably two parallel actuated lifting cylinders are provided) will be moved already at a lower hydraulic pressure, so that commencing from the bottom loading and 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 6 unloading position with relieved cylinders by actuating the hydraulic pump first the lifting cylinders are actuated and thus the platform carrier is pivoted upwards. The end of this pivoting movement is preferably determined 5 by a mechanical stop of the platform carrier on the rear end of the loading area, so that there is no need to provide an additional valve or a corresponding complex control. However, the mechanical stop can be basically provided, for example, directly on the lifting arm, or an 10 appropriate design of the lifting cylinder can limit its movement. By virtue of the mechanical limitation of the pivoting movement of the lifting arm the outlet pressure increases 15 in the hydraulic line while the hydraulic pump is further operated, so that subsequently the locking cylinder will be actuated and the loading platform is pivoted upwards. The top position of the loading platform can be limited by an appropriate design of the locking cylinder or by a 20 mechanical limitation of the pivoting movement of the loading platform. In the top locked position of the loading platform preferably a mechanical locking is carried out, by, for example, a locking hook. 25 Thus the operator can affect the movement by simply actuating the actuating means, e.g. a button or a lever. When actuating this actuating means, commencing from the bottom loading and unloading position first the lifting arm is pivoted upwards until the top loading and unloading 30 position is reached. Should the operator following this further actuate the actuating means, the loading platform is pivoted upwards until the loading area is closed. Thus according to embodiments of the invention a 35 surprisingly simple construction of the hydraulic control and of the entire tailgate loader is achieved, wherein merely the cylinders are appropriately designed, so that 5013708_1 (GHMatters) P76955.AUS013708_1 (GHMatters) P76955.AU 10/01/14 - 7 the sequence of the movement is determined. External check valves, i.e. check valves intended outside of the hydraulic module are according to the invention, 5 not necessary. Thus, in embodiments no electrical control lines from the hydraulic module to the cylinders are required either. The hydraulic module itself can also have a relatively simple design, e.g. with a non-return valve to close the outlet hydraulic pressure present in the 10 external hydraulic line and a 2/2 -way acting valve to release the hydraulic pressure, i.e. when lowering the loading platform and the platform carrier. For pressure limitation a pressure-limiting valve can be provided. A volume control valve, e.g. a pressure-compensated volume 15 control valve, can be provided as a braking valve for lowering, so that the speed of lowering of the loading platform as well as of the lifting arm can be adjusted independently from the load. This volume control valve is preferably connected with the hydraulic reservoir via a 20 check valve, e.g. a 2/2 way valve with flow-through position and double-sided locking position. Consequently a system, that has a simple construction, yet enables a complete movement, can be produced. Thus the 25 tailgate loader can be cost-effectively produced and allows a total operation without safety problems. Since only few actuating means, e.g. only one switch is required to pivot upwards first the lifting arm and subsequently the loading platform and correspondingly to lower it, 30 maloperations are ruled out to a great extent. The locking cylinder can be advantageously connected to the common external hydraulic line via a throttle to limit the opening and locking speeds. Corresponding throttles 35 are also feasible for the lifting cylinders, but are essentially not required. 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 8 Thus according to an embodiment of the invention a single common outlet line can be connected to the hydraulic module, said outlet line leading to the tailgate loader and connected there to the lifting cylinder and the 5 locking cylinder. Thus the expense of the external hydraulic line is markedly reduced when compared with conventional systems, wherein the individual cylinders are separately controlled. 10 The invention is explained in the following on an embodiment based on the attached drawings. They show in: Fig.1 - a tailgate loader according to an embodiment of the invention, fastened on a truck, in the lowered, 15 lowermost loading and unloading position, Fig.2 - the top loading and unloading position of the loading platform, 20 Fig.3 - the locked transport position of the tailgate loader, Fig.4 - a hydraulic circuit of the tailgate loader according to an embodiment of the invention, 25 Fig.5 - a top view of the tailgate loader, with the piping shown. A rear section of a vehicle frame 2 of a truck 1 is shown, 30 with its loading area 3. On the vehicle frame 2 a tailgate loader 4 according to an embodiment of the invention is mounted. In this connection a carrying body 5 is fastened in the lower region of the vehicle frame 2, screwed on, for example. On the carrying body 5 a lifting arm 6 is 35 articulately joined, on the rear end of which a platform carrier 7 is articulately joined. With the carrying arm 9, also articulately joined on the right side of the carrying 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 9 body 5 and on the platform carrier 7, and a locking cylinder 14, mounted on the left, the lifting arm 6 forms a parallel linkage for the platform carrier 7. For the pivoting of the lifting arm 6 two, preferably parallel, 5 hydraulic lifting cylinders 8 are articulately joined on the carrying body S and the lifting arm 6, while in the side views of Figs.1-3 only one lifting cylinder 8 is visible. 10 According to Fig.4 the lifting cylinders 8 are single acting and have a diameter, for example, of 35 mm. To the platform carrier 7 a loading platform 10 is articulately joined, that, as it is shown in the embodiment, is made from one piece but can be made from two pieces, whereby a 15 front platform portion is articulately joined on the platform carrier 7 and joined with a rear platform portion via a joint or hinge and can be folded up on the front platform portion. 20 The movement of the loading platform 10 is carried out via a locking cylinder 14, that is articulately joined between the platform carrier 7 and the carrying body 5. The locking cylinder has an inside diameter of, for example, 15mm; thus the hydraulic fluid introduced builds up on the 25 piston 8a of each lifting cylinder 8 a greater force than on the smaller pistons 14a of the locking cylinder 14. Thus with the same hydraulic pressure in both lifting cylinders and in the locking cylinder 14 the lifting cylinder 8 will be actuated already at a lower hydraulic 30 pressure than the locking cylinder 14. The control of the three cylinders 8, 8 and 14 according to an embodiment of the invention is carried out via a common hydraulic outlet line 16, that is connected to a 35 hydraulic connection 17 of a hydraulic unit 18. According to an embodiment of the invention and advantageously the hydraulic outlet line 16 is connected without further 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 10 check valves to the hydraulic chambers 8b and 14b of the cylinders 8 and 14. Advantageously, a throttle 32 is provided between the outlet line 16 and the locking cylinder 14. 5 The hydraulic unit 18 according to an embodiment of the invention has, according to Fig.4, a hydraulic pump 20 driven by an electric motor 19, the pump conveying hydraulic fluid from a hydraulic reservoir (hydraulic 10 bath) 21, while the outlet of the hydraulic pump 20 is returned to the hydraulic reservoir 21 via a pressure limiting valve 22. To the hydraulic pump 20 the outlet connector 17 of the hydraulic unit 18 is directly connected via a non-return valve 23 and a Minimess 15 connector 24 (external connection for valve adjustment) via a further non-return valve 27, and additionally a pressure-compensated volume control valve 26. The pressure-limiting valve 22 can be adjusted when the Minimess valve 24 is pressurised. The hydraulic reservoir 20 21 is connected in turn to the pressure-compensated volume control valve 26 via a 2/2-way valve 28, that in the inactivated position has a closed position and in the activated position a flow-through position. The check valve 28, just like the motor 29, is actuated by a control 25 device (not illustrated), that is activated by the operator by a button or a lever. The valves 22, 23, 26, 27, 28 form a control valve device 29 in the hydraulic unit 18. 30 In the following the locking and opening operations of the tailgate loader is described. Fig.1 shows the loading and unloading position lowered on the ground 33, with the cylinders 8, 14 relieved, corresponding to the switched state of Fig.4. Following this, by actuating the motor 19, 35 the outlet line 16 is pressurised by the hydraulic pump 20, while the check valve 28 remains in the closing resting position, i.e. it is not actuated. Because 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 11 according to an embodiment of the invention first only the two lifting cylinders 8 are actuated, the lifting arm 6 is pivoted upwards by its piston rods 8d and thus the platform carrier 7 is pivoted into the top and unloading 5 position, shown in Fig.2, until it abuts against the rear end 3a of the loading area 3. In this first movement phase the locking cylinder 14 is not actuated, since the pressure, built up in the line 16, due to the small piston area does not overcome the counterforce of the platform's 10 weight. During the following actuation of the motor 19 the pressure in the outlet line 16 increases, so that in a second movement phase (immediately following the first 15 movement phase or after a loading and unloading) the locking cylinder 14 will now be actuated and according to Fig.3 the loading platform 10 is pivoted upwards into the locked position, in which the fully extended position of the locking cylinder 14 is reached. In this top travelling 20 position the loading platform 10 can be secured by a locking hook. In the travelling position the pressure is stored in the outlet line 16, while the check valve 28 is closed. 25 For the discharging first the locking hooks are released and by opening the check valve 28 with the motor 19 not operating, first the hydraulic fluid (oil) is pressed back by the locking cylinder 14, since the small locking cylinder piston 8a[sic] produces a greater retracting 30 pressure than the lifting piston 8a. In addition, advantageously an opening spring 35, e.g. a torsion spring or a pneumatic spring, is provided in the locking cylinder 14 to support the opening operation of the loading platform 10. Only when the platform 10 is open, i.e. when 35 the locking cylinder 14 is retracted, falls the locking pressure below the lifting pressure and the hydraulic fluid (oil) of both lifting cylinders 8 flows through the 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 12 volume control valve 26 and the open check valve 28 back to the hydraulic tank 21, until the platform 10 has reached the ground 33. 5 Depending on the weight of the platform 10 and the force of the opening spring 35 a certain overlap of the opening and lowering movements may occur, i.e. the platform is lowered during the opening. The advantage of this is that the operating time of the tailgate loader is somewhat 10 shortened. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary 15 implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 20 It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any 25 other country. 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14

Claims

1. Hydraulically actuated tailgate loader for a truck, that has at least: 5 one carrying structure for fastening it on the truck, one pivotable lifting arm that can be articulately joined to the carrying structure, one platform carrier provided on the external end of the lifting arm, at least one lifting cylinder to pivot the lifting arm, 10 one pivotable loading platform to accept the loads that is articulately joined to the platform carrier, at least one locking cylinder articulately joined between the platform carrier and the carrying structure for pivoting the loading platform, and 15 one hydraulic module with a hydraulic pump to supply the at least one lifting cylinder and the at least one locking cylinder with hydraulic fluid, wherein: the at least one lifting cylinder and the at least one 20 locking cylinder have a single-acting construction, in the case of a relieved lifting cylinder the lifting arm is in its bottom position and in the case of a relieved locking cylinder the loading platform is in its bottom position, 25 the at least one lifting cylinder and the at least one locking cylinder are connected to a common outlet line system originating from the hydraulic module, wherein the at least one lifting cylinder and the locking cylinder are connected to the outlet line system without check valves. 30 andthe at least one lifting cylinder can be actuated at a lower hydraulic pressure than the at least one locking cylinder.

2. A tailgate loader according to claim 1, wherein the at 35 least one lifting cylinder and the at least one locking cylinder are charged with the same hydraulic pressure by the hydraulic module via the outlet line system 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 14

3. A tailgate loader according to claim 1 or 2, wherein the locking cylinder is connected to the common external outlet line via a throttle. 5

4. A tailgate loader according to any one of the preceding claims, wherein in its top pivoted position the lifting arm is stopped by a stop on the vehicle, e.g. a stop of the platform carrier or of the lifting arm on a 10 rear end of the loading area.

5. A tailgate loader according to claim 4, wherein when the hydraulic pump is actuated from the bottom loading and unloading position of the loading platform and of the 15 lifting arm in a first movement phase first the at least one lifting cylinder is actuated and the lifting arm is pivoted upward until it is stopped by the stop, and subsequently while the pressure is increased by the hydraulic pump in a second movement phase the at least one 20 locking cylinder is actuated and the loading platform is pivoted upwards.

6. A tailgate loader according to any one of the preceding claims, wherein in a top, essentially vertical pivoted 25 position, the loading platform can be locked by a mechanical locking, e.g. a locking hook.

7. A tailgate loader according to any one of the preceding claims, wherein from a top travelling position with upward 30 folded loading platform a lowering follows, wherein, possibly after releasing the mechanical locking, with a non-actuated motor and open check valve the downward pivoting loading platform presses the hydraulic fluid from the locking cylinder and in the case of an at least 35 partially opened platform and at least partially retracted locking cylinder the locking pressure exerted by the loading platform falls below the lifting pressure and 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 15 presses back the hydraulic fluid of the at least one lifting cylinder into the hydraulic tank.

8. A tailgate loader according to any one of the preceding 5 claims, wherein two parallel actuated lifting cylinders are provided.

9. A tailgate loader according to any one of the preceding claims, wherein the at least one lifting cylinder has a 10 greater piston diameter than the at least one locking cylinder.

10. A tailgate loader according to any one of the preceding claims, wherein a valve control system is 15 provided in the hydraulic module that has: a non-return valve provided between the hydraulic pump and an outlet connector of the hydraulic unit and a pressure-limiting valve provided between the outlet of the hydraulic pump and a hydraulic reservoir. 20

11. A tailgate loader according to claim 10, wherein the valve control system includes a control valve that is pressure compensated. 25

12. A tailgate loader according to any one of the preceding claims, wherein an opening spring, e.g. a torsion spring or a pneumatic spring is provided in the locking cylinder to support the opening operation of the 30 loading platform.

13. A tailgate loader according to any one of the preceding claims, wherein the lifting arm, the at least one lifting cylinder and the locking cylinder are 35 articulately joined to a carrying body acting as carrying structure, that is provided for the fastening on the vehicle structure, e.g. on the vehicle frame of the truck. 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14 - 16

14. A tailgate loader substantially as described herein with reference to the accompanying drawings. 5

15. A truck with a tailgate loader according to any one of the preceding claims, wherein the carrying structure is fastened on the vehicle frame of the truck and in its top pivoted position the platform carrier abuts against a stop of the truck, e.g. the rear end of its loading area. 5013708_1 (GHMatters) P76955.AU5013708_1 (GHMatters) P76955.AU 10/01/14