Title of Invention: CONVEYOR APPARATUS

Technical Field

[0001] The present invention relates to a conveyor apparatus capable of changing a height of a work support platform on a conveyance carriage according to the type of work being supported. Background Art

[0002] On an automobile assembly line, a vehicle body is conveyed being supported on a conveyance carriage. However, on lines where the working range with respect to the vehicle body is lower than the floor level of the conveyance carriage, such as trimming process or final process, it is necessary to support the vehicle body on the conveyance carriage at a low level; while on lines where the working range to the vehicle body work is higher than the floor level of the conveyance carriage, such as chassis process, it is necessary to support the vehicle body on the conveyance carriage at a high level. In other words, there is a need to elevate or lower the vehicle body to a different level on the conveyance carriage for each travel path section to change the height of the vehicle body from the perspective of the conveyance carriage.

[0003] Conventionally, as a means of changing the height of a vehicle body on a conveyance carriage for each travel path section, as described in Japanese Laid Open Patent Publication No. 2007-153178, a structure has been adopted that supports for separately supporting left and right sides of a vehicle body are supported on a conveyance carriage by means of an extendable support apparatus, which can be extended and retracted perpendicularly. Further, although patent literature cannot be referred, a method of exchanging the supports for supporting the vehicle body on the conveyance carriage for those of a different height is also conceivable.

[0004] PTL 1: Japanese Laid Open Patent Publication No. 2007-153178 Disclosure of Invention Task to be Solved by the Invention

[0005] In a structure using an extendable support apparatus such as that disclosed in

Japanese Laid Open Patent Publication No. 2007-153178, it is necessary to provide large and structurally complex extendable support apparatus for all of the conveyors. Furthermore, since working floor surfaces must also be established below vehicle bodies, a pair of large and structurally complex extendable support apparatus must be set up in parallel left and right sides of the conveyors, respectively, so that left and right sides of the vehicle bodies can be separately supported. Consequently, not only are conveyor costs exceptionally high, but since such large extendable support apparatus are disposed on left and right sides of the conveyors, the low-floored structure of the conveyors could not be realized. In addition, since the working floor surface around the vehicle bodies to be supported becomes small, there have also been problems in terms of workability. On the other hand, in the method of exchanging the support platforms supporting the vehicle body on the conveyor for supports of a different height, even though the conveyor cost can be reduced, there is still the downside that the exchange of the vehicle body supports is labor intensive and expensive. Means for Solving the Task

[0006] The present invention proposes a conveyor apparatus capable of solving the above- mentioned problems. Referring to the numerical references in the embodiments described below, the conveyor apparatus described in Claim 1 comprises a pair of left and right first supporting means 6 A and 6B for supporting a work support platform 15 at a low level and a pair of left and right second supporting means 7A and 7B for supporting the work support platform 15 at a high level on a conveyance carriage 1 travelling on a fixed travel path; wherein each of the second supporting means 7A and 7B comprises fore and aft pairs of standing/reclining struts l la and 1 Ib being capable of freely standing/reclining between a reclining position, at which the standing/ reclining struts recline in fore and aft directions being separated from each other on fore and aft sides of the first supporting means 6 A and 6B, and a standing position, at which upper ends 14 of the standing/reclining struts 1 Ia and 1 Ib abut together to form triangles when viewed in profile; and wherein the work support platform 15 is provided with supported members 19 to be supported by means of the abutted upper ends 14 of the fore and aft pairs of standing/reclining struts 1 Ia and 1 Ib in the standing position; and wherein elevating apparatus 29A and 29B for elevating/lowering the work support platform 15 between the low level, at which the work is supported by the first supporting means 6 A and 6B, and the lifting level which is higher than the high level, at which the work is supported by the second supporting means 7 A and 7B, are provided at a work support level switching position on the travel path.

[0007] In one implementation of the present invention, specifically as described in Claim 2, the upper ends 14 of the fore and aft pairs of the standing/reclining struts 1 Ia and 1 Ib may be provided with engaging members 14a being interfitting in a fore and aft direction and thereby preventing relative displacement in a vertical direction when the standing/reclining struts l la and 1 Ib are in the standing position, thereby the upper ends 14 abut together and the supported members 19 provided on the work support platform 15 may comprise cylinders 21 for engaging over the abutted upper ends 14 of both the standing/reclining struts 1 Ia and 1 Ib. In this case, as described in Claim 3, the supported members 19, provided on the work support platform 15 may be provided with coupling pins 23, which are capable of freely inserting/removing in a horizontal direction to locking holes 14b provided on the abutted upper ends 14 of both the standing/reclining struts 11a and 1 Ib, and with springs 24 for holding the coupling pins 23 biased in an inserted position. Furthermore, in such cases, as described in Claim 4, the elevating apparatus 29A and 29B may be provided with elevator bodies 32 for elevating/descending on left and right sides of the travel path of the conveyance carriage 1, wherein the elevator bodies 32 are provided with supports 50a and 50b, which are capable of extending/retracting in a horizontal direction for supporting in an extended state the work support platform 15, and with coupling pin operating means 51 for inserting/removing the coupling pins 23 when the supports 50a and 50b are supporting the work support platform 15.

[0008] It is also possible to cause the fore and aft pairs of standing/reclining struts 11a and 1 Ib of the second supporting means 7A and 7B to stand or recline between the reclining position and the standing position by means of actuators such as motors or cylinders provided on the conveyance carriage 1. Of course, when the fore and aft pairs of standing/reclining struts 11a and 1 Ib are comparatively small and light weight in structure, the fore and aft pairs of standing/reclining struts 11a and 1 Ib may be constructed such as to stand/recline manually. However, in the case that the standing/ reclining struts 1 Ia and 1 Ib are caused to stand/recline by the power of actuators, as described in Claim 5, the work support level switching position on the travel path may be provided with switching apparatus 30A and 30B for causing the fore and aft pairs of standing/reclining struts 11a and 1 Ib of the second supporting means 7 A and 7B to stand or recline between the reclining position and the standing position. In this case, as described in Claim 6, to the fore and aft pairs of standing/reclining struts 11a and 1 Ib of the second supporting means 7A and 7B are connected operated levers 60 moving in a fore and aft direction being engaged to the standing/reclining movement thereof, and to the switching apparatus 30A and 30B are provided switching means 59a and 59b for moving the engageable/disengageable operating bodies 62 in a left and right horizontal direction with respect to the operated lever 60 so as to cause the standing/reclining struts 11a and 1 Ib to stand/recline between the reclining position and the standing position.

[0009] Further, as described in Claim 7, accommodating recessed portions 12 may be formed underfloor of the conveyance carriage 1 for accommodating the fore and aft pairs of standing/reclining struts 11a and 1 Ib of the second supporting means 7 A and 7B when both the standing/reclining struts 11a and 1 Ib are in a reclining position; with the accommodating recessed portions 12 are provided freely opening/closing cover plates 12a, and with the switching apparatus 30A and 30B are provided cover plate opening/closing apparatus 31A and 3 IB for operating the cover plates 12a by means of an elevating movement of the apparatus (a perpendicularly linear elevating movement or a vertically rotating movement around a left and right horizontal axis).

[0010] The work support platform 15 may also be separately provided with supported members supported by the first supporting means 6A and 6B and supported members supported by the second supporting means 7 A and 7B. However, as disclosed in Claim 8, the first supporting means 6 A and 6B may have a construction such that they have supports 8 for supporting the work support platform 15 via the supported members 19 being borne on the second supporting means 7 A and 7B.

[0011] Additionally, it is acceptable that the first supporting means 6 A and 6B for supporting the work support platform 15 at a low level supports the work support platform 15 only at a fixed level where the work support platform is incapable of elevating/lowering in relation to the conveyance carriage 1. However, as disclosed in Claim 9, the first supporting means 6A and 6B may have elevating struts 8 which are capable of elevating/lowering the work support platform 15 between a first low level and a second low level being higher than the first low level, and cam rails 27 and 28 may be disposed along the travel path for raising the elevating struts 8 from a height corresponding to the first low level to a height corresponding to the second low level and maintaining the elevating struts 8 at the height corresponding to the second low level. Effects of the Invention

[0012] According to the conveyor apparatus of the present invention disclosed in the above- mentioned Claim 1, in the case that the support level of the work support platform being supported by means of the left and right pair of the first supporting means is switched to the high level, the work support platform being supported at the lower level by the elevating apparatus on the travel path is lifted to the lifting lever, which is higher than the high level, while the conveyance carriage is being stopped at the work support level switching position. In such a condition, the fore and aft pairs of standing/ reclining struts of the second supporting means are raised from the reclining position to standing position so that the upper ends of the standing/reclining struts are disposed adjacent together, while the elevator lowers the work support platform supported at the higher level so as to make the supported members of the work support platform engage with the upper ends of the fore and aft pairs of standing/reclining struts being adjacent together, thereby the work support platform can be supported by the second supporting means at the higher level. Switching the work support platform being supported at the high level to the low level can be achieved by the elevating operation of the work support platform by means of the elevating apparatus and the switching operation for the fore and aft pairs of standing/reclining struts of the second supporting means from the standing position to the reclining position with the opposite procedure of the above. [0013] Furthermore, according to the conveyor apparatus of the present invention disclosed in Claim 1, the support height of the work support platform on the conveyance carriage may be switched between the low level and the high level by elevating/lowering the work support platform by means of the elevating apparatus and by causing the fore and aft pairs of standing/reclining struts of the second supporting means to stand/recline. However, it is possible to extensively reduce conveyance carriage costs even if a structure is applied that causes the fore and aft pairs of standing/reclining struts of the second supporting means to stand/recline by means of actuators such as motors or cylinders on the conveyance carriage, since the structure of supporting means for work support platforms on a conveyance carriage can very easily be implemented at reasonable cost compared to the conventional structure of vertically extending/retracting supporting apparatus installed on both left and right sides of the conveyance carriage. In addition, when not using the fore and aft pairs of standing/reclining struts of the second supporting means, the standing/reclining struts can easily be reclined in fore and aft directions to be separated, thus constructing a conveyance carriage with a low-floored structure can be obtained easily, compared to the conventional structure of applying the extending/retracting supporting apparatus. Furthermore, in the case of the conventional extending/retracting supporting apparatus, in order to increase the support strength in a fully extended state to support work support platforms at the high level, it is necessary to construct the extending/retracting supporting apparatus with a large diameter. In comparison, according to the structure of the present invention where fore and aft pairs of standing/reclining struts are assembled to form triangles when viewed in profile, the space taken up by the pairs of standing/reclining struts can be kept comparatively small while easily obtaining the required supporting strength, even when the support level of the work support platform is sufficiently raised.

[0014] According to the structure described in Claim 2, the upper ends, being abutted together, of the fore and aft pairs of standing/reclining struts being in a standing position, do not move relatively in a vertical direction, and the cylinders of the supported members on the work support platform engage over the upper ends in such condition. Consequently, the fore and aft pairs of standing/reclining struts supporting the work support platform such as to form triangles when viewed in profile are securely independent, and therefore, the safety is enhanced when supporting the work support platform at the high level. In this case, according to the structure described in Claim 3, since both the upper ends of both the standing/reclining struts and the supported members (the cylinders) of the work support platform engaging thereover are interlocked by means of coupling pins, the safety is further enhanced. Additionally, according to the structure described in Claim 4, the coupling pins may be mechanically engaged/disengaged in a timely manner when supporting and elevating/lowering the work support platform by means of the elevating apparatus.

[0015] Furthermore, according to the structure described in Claim 5, it is unnecessary to mount the switching apparatus for causing the fore and aft pairs of standing/reclining struts of the second supporting means on the conveyance carriage to stand/recline between the reclining position and the standing position, and thus conveyance carriage costs can be further reduced. In this case, according to the structure described in Claim 6, the movement of the struts can be achieved only by providing operated levers on the conveyance carriage moving in a fore and aft direction being coordinated with the standing/reclining struts of the second supporting means, so that the structure on the conveyer side becomes simpler. It not only helps to minimize the conveyance carriage costs, but the structure of the switching apparatus installed on the travel path side also becomes simple and it can easily be implemented.

[0016] Additionally, according to the structure described in Claim 7, the fore and aft pairs of standing/reclining struts in the reclining position of the second supporting means can be accommodated in the accommodating recessed portions underfloor, and furthermore, the accommodating recessed portions can also be closed with cover plates. Thus, a wide working floor area can be obtained on the conveyance carriage when not using the second supporting means, that is to say, when the work support platform is supported by the first supporting means. Additionally, when opening the cover plates of the accommodating recessed portions prior to using the second supporting means, the operation therefor can be conducted mechanically by means of the cover plate opening/closing apparatus disposed with the switching apparatus on the travel path.

[0017] Furthermore, the first supporting means may also use dedicated supported members for the first support means, which is different from the supported members supported by the second supporting means, to support the work support platform. However, according to the structure described in Claim 8, the work support platform can be supported by the first supporting means using the supported members supported by the second supporting means, and thus the structure of the work support platform becomes simple.

[0018] When it is preferable to support the work support platforms at one of the low levels, the first supporting means may be fixed to the conveyance carriage. However, when it is necessary to change the support level of the work support platform between the first low level and the second low level being higher than the first low level, according to the structure described in Claim 9, the change may easily be implemented without providing the conveyance carriage with power sources (actuators such as motors or cylinders) for switching the support level of the first support means. Brief Description of Drawings [fig.1] Fig. 1 is a side view of a conveyance carriage in a section where a work support platform is supported at a first low level. [fig.2]Fig. 2 is a front elevation of Fig.l.

[fig.3]Fig. 3 is a side view of a conveyance carriage when it advances into a section wherein a work support platform is supported at a second low level higher than the first low level.

[fig.4]Fig. 4 is a front elevation of Fig. 3.

[fig.5]Fig. 5 is a side view of a conveyance carriage in a section where a work support platform is supported at a high level, [fig.6] Fig. 6 is a front elevation of Fig. 5.

[fig.7]Fig. 7 is a plan view of a conveyance carriage in a section where the above- mentioned work support platform is supported at a first low level or a second low level.

[fig.8]Fig. 8 is a plan view of each apparatus disposed at a work support level switching position in a travel path.

[fig.9]Fig. 9 is a rear elevation of a conveyance carriage in the above-mentioned work support level switching position.

[fig.10] Fig. 10 is a front elevation showing one elevator body of an elevating apparatus and the elevator driving means thereof.

[fig.1 l]Fig. 11 is a cross-sectional side view showing one elevator body of an elevating apparatus and the elevator driving means thereof.

[fig.l2]Fig. 12A is a cross-sectional plan view showing one elevator body of an elevating apparatus; Fig. 12B is a side view showing a coupling pin operating means provided on the abovementioned elevator body.

[fig.l3]Fig. 13 is a side view showing an operating apparatus for opening and closing a cover plate of an accommodating recessed portion for struts of the conveyance carriage.

[fig.l4]Fig. 14 is a cross-sectional front elevation showing the abovementioned operating apparatus in a state of opening a cover plate.

[fig.l5]Fig. 15 is a side view showing one part of a second supporting means for supporting a work support platform at a high level and one part of a switching apparatus therefor.

[fig.l6]Fig. 16 is a pian view of Fig. 15. [fig.l7]Fig. 17 is a front elevation of Fig. 15.

[fig.18]Fig. 18 is a partial cross-sectional side view showing a main section of the work support platform when supporting the work support platform by means of a first supporting means. [fig.l9]Fig. 19 is a partial cross-sectional side view showing a state of a main section immediately prior to supporting a work support platform by means of a second supporting means.

[fig.20]Fig. 20 is a partial cross-sectional side view showing a main section when the work support platform is supported by means of a second supporting means. [fig.21]Fig. 21A is a partial rear elevation view showing a first stage of working process for supporting a work support platform being supported at a second low level by means of a second supporting means; Fig 2 IB is a partial rear elevation showing a second stage of the above.

[fig.22]Fig. 22A is a partial rear elevation view showing a third stage of the above- mentioned working process; Fig 22B is a partial rear elevation view showing a fourth stage of the same. Reference Signs List 1 : conveyance carriage

6 A, 6B: first supporting means

7 A, 7B: second supporting means

8: elevating strut

8 a: upper end

8b, 14b: locking holes

10: cam follower roller

11a, l ib: standing/reclining struts

12: accommodating recessed portion

12a: cover plate

13, 72: left and right horizontal axes

14: upper end

14a: engaging member

15: work support platform

16 A, 16B: supports

19: supported member

20a, 20b: horizontal rectangular holes

21: cylinder

22: coupling means

23: coupling pin

23a: small diameter operable shank

24: coil spring

26: low cam rail

27: high cam rail

28: sloping cam rail 29A, 29B: elevating apparatus 30A, 30B: switching apparatus 3 IA, 3 IB: cover plate opening/closing apparatus 32: elevator body 33: elevator driving means 36a, 36b: supporting structures 37: elevator guide rail 38, 48, 52, 65, 68: slide guides 39: extendible/retractable slide 40: motor, having a reducer and a break 41: large diameter gear 42: chain 43: guiding gear 47, 53, 64, 67: slide guide rails 49a, 49b, 56, 66, 69, 75: cylinder units 50a, 50b: supports 51 : coupling pin operating means 54: movable body 57: operating plate 57a: engaging depression 59a, 59b: switching means 60a, 73 a: rollers 61: movable platform 62: operating body 62a: hollow grooved member 70a, 70b: cover plate opening/closing means 73: cover plate lifting lever 76: conveyance carriage positioning apparatus 77: locking piece 80: cam

Mode for Carrying Out the Invention As shown in Figs. 1-7, a conveyance carriage 1 used in the present invention comprises fore and aft pairs of left and right wheels 3 rotating on a pair of left and right guide rails 2a and 2b disposed along a travel path, respectively, and fore and aft pairs of bracing roller units 5 comprising a pair of left and right rollers gripping left and right sides of a bracing guide rail 4, which are disposed along the travel path being adjacent to one of the guide rail 2b. It is not shown in the drawings, but a variety of conventional drive means can be used to cause a conveyance carriage to travel along the travel path, for instance, a drive means rotating one or more wheels 3 by means of a motor, or a friction transmission drive means comprising motor-powered friction drive wheels being applied with pressure to one of the sides parallel to the direction of travel of the conveyance carriage 1 and back-up rollers being applied with pressure to another side.

[0022] On left and right sides of the conveyance carriage 1, a pair of left and right first supporting means 6 A and 6B, and pairs of left and right second supporting means 7 A and 7B are disposed in an intermediate position in the fore and aft direction. The pair of left and right first supporting means 6A and 6B have rectangular elevating struts 8 vertically penetrating through the conveyance carriage 1. The elevating struts 8 are supported such as to be only capable of vertical elevation by means of four upper and lower groups of circumferential rollers (rotatably supported on the horizontal axes), which are provided on elevation guide means 9 attached to the bottom of the conveyance carriage 1 and are arranged to be rotatable while being in close contact with the four sides of the elevating struts 8, respectively, and lower ends of the elevating struts 8 having cam-follower rollers 10 rotatably supported by left and right horizontal axes. The second supporting means 7A and 7B have fore and aft pairs of standing/reclining struts 11a and 1 Ib disposed on the fore and aft of the elevating struts 8 of the first supporting means 6 A and 6B.

[0023] The pairs of standing/reclining struts 11a and 1 Ib, are rotatably supported by means of left and right horizontal axes 13 at an inner end, which is adjacent to the elevating struts 8 within accommodating recessed portions 12 formed underfloor of the conveyance carriage 1 lengthwise to the direction of travel, and are configured to swing universally about the left and right horizontal axes 13 between a reclining position accommodated into the accommodating recessed portions 12 and a standing position, where upper ends 14 are adjacent to each other to form equilateral triangles when viewed in profile. On the accommodating recessed portions 12 in which the standing/reclining struts 11a and 1 Ib in a reclining position are accommodated, as shown in Figs. 7, 13 and 14, cover plates 12a are provided. They are flush with a floor of the conveyance carriage 1 when the cover plates 12a are closed, and are rotatably supported to swing vertically open/closed freely by means of hinges 12b on medial side edges of the accommodating recessed portions 12 in a crosswise direction to the conveyance carriage 1, and further are biased in a closing direction by means of helical torsion coil springs 12c.

[0024] A work support platform 15 is supported selectively by means of the first supporting means 6 A and 6B or the second supporting means 7 A and 7B, and comprises a pair of supports 16A and 16B for separately supporting both left and right sides of a work, that is a vehicle body W in an automobile assembly line. Each of the supports 16A and 16B comprises a frame material 17 in a fore and aft horizontal direction, a fore and aft pair of supporting arms 18 extending from the frame material 17 on interior sides, and a supported member 19 protruding downward in an approximately medial position from an underside of the frame material 17. Each frame material 17 has a fore and aft pair of outward opening horizontal rectangular holes 20a and 20b provided. The supported members 19 comprise rectangular open bottom cylinders 21, which are capable of accommodating both upper ends of the elevating struts 8 of the first supporting means 6A and 6B, and the two abutted upper ends 14 of the standing fore and aft pairs of standing/reclining struts 1 Ia and 1 Ib of the second supporting means 7A and 7B, respectively. The cylinders 21 (the supported members 19) have coupling means 22 attached thereto.

[0025] As shown in Figs. 18 and 19, the coupling means 22 comprise coupling pins 23 capable of transversely penetrating the cylinders 21 in a fore and aft horizontal direction and coil springs 24 holding the coupling pins 23 biased in an extended position for transversely penetrating the cylinders 21. The coupling pins 23 have small diameter operable shanks 23 a formed on the outer ends thereof. Casings 25 protrude rearward from the cylinders 21, supporting the outer ends of the coupling pins 23 in addition to covering the coil springs 24. Furthermore, rectangular-cylindrical upper ends 8a of the elevating struts 8 of the first supporting means 6A and 6B are provided with locking holes 8b, through which the coupling pins 23 being capable of transversely penetrating when the upper ends 8a engage within the supported members 19 (the cylinders 21) on the supports 16A and 16B such as to be incapable of relative rotation, and bear the supports 16A and 16B.

[0026] Further, as shown in Figs. 19 and 20, on the upper ends 14 of the pairs of standing/ reclining struts 11a and 1 Ib of the second supporting means 7 A and 7B are formed rack gear-like engaging members 14a, such that they interfit together in a fore and aft direction and thereby prevent relative displacement in a vertical direction of both the upper ends 14 when both the standing/reclining struts 1 Ia and 1 Ib stand and the upper ends 14 abut fore and aft. When both the upper ends 14 of the standing/reclining struts 11a and 1 Ib abut fore and aft such that the engaging members 14a are in an interfitting state, the two upper ends 14 are rectangular and of an approximately identical size to the upper ends 8a of the elevating struts 8 of the first supporting means 6A and 6B, and engage within the supported members 19 (the cylinders 21) on the supports 16A and 16B such as to be incapable of relative rotation, bearing the supports 16A and 16B, and locking holes 14b, through which the coupling pins 23 are capable of transversely penetrating, extending over the upper holes 14.

[0027] In the travel path of the conveyance carriage 1 of the abovementioned structure are disposed: a first conveyance carriage section, as shown in Figs. 1 and 2, for supporting and conveying the work support platform 15 (the supports 16A and 16B), which support a vehicle body W thereon, at a first low level by means of the elevating struts 8 of the first supporting means 6A and 6B; a second conveyance carriage section, as shown in Figs. 3 and 4, for supporting and conveying the work support platform 15 (the supports 16A and 16B), which support the vehicle body W thereon, at a second low level being higher than the first low level by means of the elevating struts 8 of the first supporting means 6 A and 6B; and a third conveyance carriage section, as shown in Figs. 5 and 6, for supporting and conveying the work support platform 15 (the supports 16A and 16B), which support the vehicle body W thereon, at a high level by means of the fore and aft pairs of standing/reclining struts 11a and 1 Ib in the standing position of the second supporting means 7 A and 7B. The first conveyance carriage section, as shown in Figs. 1 and 2, has tie plate low cam rails 26 disposed on a floor surface, where the low cam rails 26 movably support the elevating struts 8 of the first supporting means 6 A and 6B via the cam follower rollers 10 attached to the lower ends thereof at a height corresponding to the first low level, and an entire weight of the vehicle body W and the work support platform 15 are supported by means of the low cam rails 26 via the pair of left and right elevating struts 8. However, the low level cam rails 26 can be omitted by applying a structure wherein braces are provided on the conveyance carriage 1 to brace the elevating struts 8 having descended to a level supported by the low level cam rails 26.

[0028] The second conveyance carriage section, as shown in Figs. 3 and 4, has tie plate high cam rails 27 disposed on the floor surface, where the high cam rails 27 movably support the elevating struts 8 via the cam follower rollers 10 attached to the lower ends thereof at a height corresponding to the second low level. In the area between the first conveyance carriage section and the second conveyance carriage section, sloping cam rails 28 are disposed along which the elevating struts 8 gradually ascend or gradually descend via the cam follower rollers 10 in accordance with a travel of the conveyance carriage 1. As the conveyance carriage 1 travels between the first conveyance carriage section and the second conveyance carriage section, the upper ends 8a of the elevating struts 8 of the first supporting means 6A and 6B engage within the supported members 19 (the cylinders 21) of the work support platform 15 (supports 6 A and 6B), as shown in Fig. 18, and bear the supports 16A and 16B, respectively. When this occurs, the coupling pins 23 of the coupling means 22 provided on the supported members 19 transversely penetrate the locking holes 8b in the upper ends 8a of the elevating struts 8, completely combining the elevating struts 8 and the supports 16A and 16B into a single integrated whole.

[0029] In the third conveyance carriage section, the fore and aft pairs of standing/reclining struts 11a and 1 Ib of the second supporting means 7 A and 7B on the conveyance carriage 1 are switched to the standing position, and, as shown in Fig. 20, the upper ends 14 of both of the standing/reclining struts l la and 1 Ib, which are adjacent together and the engaging members 14a interfit together, engage within the supported members 19 (the cylinders 21) of the work support platform 15 (the supports 16A and 16B), thereby supporting the supports 16A and 16B at the high level. When this occurs, the coupling pins 23 of the coupling means 22 provided on the supported members 19 transversely penetrate the locking holes 14b in the upper ends 14 of the standing/reclining struts l la, l ib, completely combining the standing/reclining struts l la, 1 Ib and the supports 16A and 16B into a single integrated whole. When the conveyance carriage 1 is traveling on the third conveyance carriage section, the elevating struts 8 of the first supporting means 6A and 6B descend to a minimum height where they are supported by the braces on the conveyance carriage 1.

[0030] By using the conveyance carriage 1 as described above, a support level of the work support platform 15 supporting the vehicle body W can be changed for each conveyance carriage section in the travel path according to a height of a working area on the floor of the conveyance carriage 1 in relation to the vehicle body W. However, when the conveyance carriage 1 is travelling in the first conveyance carriage section or the second conveyance carriage section, supporting the work support platform 15 at the first low level or the second low level being higher than the first low level, the fore and aft pairs of standing/reclining struts l la and 1 Ib of the second supporting means 7 A and 7B are accommodated underfloor within the accommodating recessed portions 12 in the reclining position and the recessed portions 12 are closed with the cover plates 12a, and thus the surface area of the floor useable as a working floor on the conveyance carriage 1 is not reduced by the second supporting means 7 A and 7B. Further, when the conveyance carriage 1 is travelling in the third conveyance carriage section, supporting the work support platform 15 at the high level, only the standing/ reclining struts l la and 1 Ib, in a standing position forming equilateral triangles when viewed in profile, are present on both the left and right sides of the work support platforms 15, and the elevating struts 8 of the first supporting means 6 A and 6B are descended to the minimum height between the fore and aft pairs of standing/reclining struts l la and 1 Ib, and thus the first supporting means 6A and 6B barely obstruct work on the floor of the conveyance carriage 1.

[0031] Switching the work support platform 15 on the conveyance carriage 1 between the first low level and the second low level being higher than the first low level can be performed automatically according to the travel of the conveyance carriage 1 by using the elevating struts 8 of the first supporting means 6A and 6B and the sloping cam rails 28. However, in order to switch the work support platform 15 supported at the second low level to the high level supported by the second supporting means 7 A and 7B, elevating apparatus 29 A and 29B, switching apparatus 30A and 30B and cover plate opening/closing apparatus 31A and 3 IB provided therewith, as shown in Figs. 8 and 9, which are disposed in the work support level switching position between the second conveyance carriage section and the third conveyance carriage section on the travel path, are used.

[0032] The elevating apparatus 29A, the switching apparatus 30A and the cover plate opening/closing apparatus 31A disposed in the above-mentioned work support level switching position correspond to one of the two supports 16A and 16B of the work support platform 15, i.e. the support 16A, and the second supporting means 7A supporting the support 16A, respectively; while the elevating apparatus 29B, the switching apparatus 30B and the cover plate opening/closing apparatus 3 IB correspond to the other support 16B and the second supporting means 7B supporting the support 16B. Consequently, each of the two sets of apparatus positioned on either of the left or right sides of the travel path of the conveyance carriage 1, that is to say, elevating apparatus 29 A and 29B, switching apparatus 30A and 30B and cover plate opening/closing apparatus 31A and 3 IB, are each symmetrical in structure and also operate in an identical manner, and therefore one of each apparatus 29A-31B will be discussed below.

[0033] The elevating apparatus 29A has an elevator body 32 and an elevator driving means 33 for driving the elevation thereof. The elevator body 32 elevates between a pair of supporting structures 36a and 36b, which are mounted on a horizontal mount 34 and parallel to the travel path of the conveyance carriage 1 with upper ends thereof being integrally connected together by means of a horizontal connecting structure 35. The elevator body 32 has slide guides 38, which are interlocked with elevator guide rails 37 being disposed on the pair of supporting structures 36a and 36b on edges of both sides, and further has an extendable/retractable slide 39 being freely reciprocating in a horizontal direction perpendicular to the travel path of the conveyance carriage 1. As shown in Figs. 10 and 11, the elevator driving means 33 comprises a motor 40 having a reducer and a break disposed on the horizontal mount 34, two large diameter gears 41 attached in parallel formation to a drive shaft 40a coupled to an output shaft of the motor 40, two parallel chains 42 one of the ends of which is locked into the large diameter gears 41, which wind the chains 42 so as to extend in an upward direction, guiding gears 43 rotatably supported on an underside of the horizontal connecting structure 35 in a central position directly above the elevator body 32 for revolving the chains 42 in a downward direction, and an approximately central point of the elevator body 32 is suspended by the two chains 42 hanging from the guiding gears 43 through vertical axis rods 44 for connecting the chains 42 attached to the elevator body 32. Therefore, the elevator body 32 is elevated in suspended state through the chains 42 by applying normal rotation to the large diameter gears 41 with the motor 40, and the elevator body 32 descends pulling the chains 42 with the gravity of the gears 41 by applying reverse rotation to the large diameter gears 41 with the motor 40. Elevating the elevator body 32 from a maximum descending position to a maximum elevating position is achieved by applying normal rotation or reverse rotation of up to one full revolution of the large diameter gears 41.

[0034] The extendable/retractable slide 39 provided on the elevator body 32 comprises a pair of vertical frame members 45a and 45b arranged in parallel along the travel path direction of the conveyance carriage 1 and in a horizontally perpendicular direction to the travel path, the vertical frame members 45a and 45b being connected to each other to form an integrated single structure in close proximity at both ends in an extending/ retracting direction via a pair of horizontal frame members 46a and 46b, where slide guide rails 47 disposed on undersides of the vertical frame members 45a and 45b in the extending/retracting direction are supported by slide guides 48 attached onto the elevator body 32. The extendable/retractable slide 39 are reciprocally driven in the extending/retracting direction in close proximity to inner sides of the vertical frame members 45a and 45b by means of two cylinder units 49a and 49b, which are interposed between the extendable/retractable slide 39 and the elevator body 32. Further, rectangular axial supports 50a and 50b are disposed such as to protrude from ends of both the vertical frame members 45 a and 45b such as to freely engage/disengage simultaneously with the horizontal rectangular holes 20a and 20b disposed on the support 16 A.

[0035] A coupling pin operating means 51 is provided on the elevator body 32. As also shown in Fig. 12, the coupling pin operating means 51 inserts/removes the coupling pin 23 of the coupling means 22 provided on the supported member 19 of support 16 A. The operating means 51 comprises a movable body 54 freely reciprocating in a horizontal direction to the extending/retracting direction of the extendable/retractable slide 39 via the slide guides 52 disposed on the elevator body 32 and the two slide guide rails 53 supported by the slide guides 52. On an end 54a of the movable body 54, is provided an operating plate 57, being supported by guide rods 55 such as to be freely extendable/retractable in an inserting/removing direction of the coupling pin 23 as well as being extendibly/retractably driven by means of a cylinder unit 56. The movable body 54, by means of being coupled via a coupling member 58 to one vertical frame member 45a of the extending/retracting slide 39, is reciprocally driven in unison with the extendable/retractable slide 39, and the piston rod of one cylinder unit 49a driving the extendable/retractable slide 39 is coupled to the coupling member 58. An engaging depression 57a is disposed on an end of the operating plate 57 such as to freely engage/ disengage with the small diameter operable shank 23a disposed on an outer edge of the coupling pin 23.

[0036] The switching apparatus 30A comprises two switching means 59a and 59b (see Fig. 8) corresponding respectively to the fore and aft pair of standing/reclining struts 11a and 1 Ib of the second supporting means 7A. As explained earlier, base ends of the fore and aft pairs of standing/reclining struts 11a and 1 Ib of the second supporting means 7A and 7B are rotatably supported within the accommodating recessed portions 12 by means of left and right horizontal axes 13. Operated levers 60 join into an underside of the conveyance carriage 1 such as to protrude from the base ends of the fore and aft pairs of standing/reclining struts 11a and 1 Ib, swinging fore and aft cooperatively with a standing/reclining action of each of the standing/reclining struts l la and 1 Ib, and rollers 60a being rotatably supported on left and right horizontal axes are provided on outer sides of ends of the operated levers 60. Furthermore, as shown in Figs. 15-17, a movable platform 61 and an operating body 62 are provided on each of the switching means 59a and 59b.

[0037] Movable platforms 61 are supported on base mounts 63 disposed on sides further from the travel path of the conveyance carriage 1 than the movable platforms 61 located at maximum retracting positions thereof by means of two pairs of slide guide rails 64, which are disposed on the base mounts 63 in a horizontally perpendicular direction to the travel path of the conveyance carriage 1, and two support members 61a extending toward the movable platforms 61 and having slide guides 65 provided on underside thereof engaging the slide guide rails 64. Furthermore, the movable platforms 61 are reciprocally driven in the horizontally perpendicular direction to the travel path of the conveyance carriage 1 by means of cylinder units 66, which are interposed between the base mounts 63 and the movable platforms 61. The operating bodies 62 are supported by slide guide rails 67 disposed on the movable platforms 61 along the direction of the travel path of the conveyance carriage 1 and slide guides 68 engaging with the slide guide rails 67, and reciprocally driven in the travel path direction of the conveyance carriage 1 by means of the cylinder units 69 disposed between the operating bodies 62 and the movable platforms 61. Hollow grooves 62a are formed in a vertical direction on the operating bodies 62 to accommodate, by means of an engaging movement toward the travel path of the conveyance carriage 1, the rollers 60a on the ends of the operated levers 60 provided on the standing/reclining struts l la and 1 Ib. The hollow grooves 62a have a vertical direction length sufficiently capable of accommodating a change in a vertical direction height of the rollers 60a when the operated levers 60 rotate fore and aft around the left and right horizontal axes 13 in connection with the standing/reclining struts l la and 1 Ib.

[0038] The cover plate opening/closing apparatus 31A comprises two cover plate opening/ closing means 70a and 70b (see Fig. 8) corresponding respectively with the cover plates 12a of the two fore and aft accommodating recessed portions 12, which are disposed on one side of the conveyance carriage 1 such as to respectively accommodate the fore and aft pair of standing/reclining struts 11a and 1 Ib of the second supporting means 7A. As shown in Figs. 13 and 14, the two cover plate opening/ closing means 70a and 70b comprise cover plate lifting levers 73 rotatably supported on base plates 71 to freely swing vertically around left and right horizontal axes 72, and cylinder units 75 interposed between arms 74, being joined with base ends of the cover plate lifting levers 73, and the base plates 71. The rollers 73a, being in direct contact with the cover plates 12a, are rotatably supported on the base ends of the cover plate lifting levers 73 by means of left and right horizontal axes.

[0039] Functions at the work support level switching position will be explained below.

When the conveyance carriage 1, in a state wherein the left and right pairs of supports 16A and 16B of the work support platform 15 are supported at a second low level L2 as shown in Figs. 3 and 4 by means of the elevating struts 8 of the first supporting means 6 A and 6B, is stopped at a given position of the work support level switching position, the supports 16A and 16B are lifted by means of the elevating apparatus 29 A and 29B, as shown in Fig. 2 IA, to a lifting level L3, which is higher than the high level supported by the second supporting means 7 A and 7B.

[0040] Thus, as shown by an imaginary line in Fig. 21, the extendable/retractable slides 39 are extended to a maximum extending position by means of cylinder units 49a and 49b on the elevator bodies 32 of elevating apparatus 29A and 29B being descended to a minimum level corresponding to the supports 16A and 16B at the second low level L2. The movable bodies 54 of the coupling pin operating means 51 are then also extended to the maximum extending position along with the extendable/retractable slides 39. As a result, the pair of supports 50a and 50b of the extendable/retractable slides 39 fit within the pair of horizontal rectangular holes 20a and 20b of the supports 16A and 16B, being at the second low level L2, and simultaneously, the engaging depressions 57a of the operating plates 57, being supported at maximum retracting positions by the movable bodies 54 of the coupling pin operating means 51, engage with the coupling pins 23 of the coupling means 22 disposed on the ends of the supported members 19 of the supports 16A and 16B, that is to say, as shown in Fig. 18, with the small diameter operable shanks 23 a of the coupling pins 23, which couple the supported members 19 (the cylinders 21) and the upper ends 8a of the elevating struts 8 accommodated therein.

[0041] In this state, as shown by the imaginary line of Fig. 12A, the operating plates 57 of the coupling pin operating means 51 are extended to the shaft center direction of the coupling pins 23 by means of the cylinder units 56, and as shown in Fig. 19, the coupling pins 23 are retracted by means of the operating plates 57 against the biasing force of the coil springs 24, thereby releasing the couplings of the supported members 19 (the cylinders 21) and the upper ends 8 a of the elevating struts 8 accommodated therein. Then, by elevating the elevator bodies 32 to a maximum elevating position by means of operating the motors 40 of the elevator driving means 33 of the elevating apparatus 29 A and 29B, the supports 16A and 16B are elevated to the lifting level L3 shown in Fig. 21 A via the pair of supports 50a and 50b of the extendable/retractable slides 39 on the elevator bodies 32. Thereby, the supported members 19 (the cylinders 21) of the supports 16A and 16B are upwardly disengaged from the elevating struts 8 of the first supporting means 6 A and 6B of the conveyance carriage 1.

[0042] Operating the cover plate opening/closing apparatus 31A and 3 IB opens the cover plates 12a of each of the accommodating recessed portions 12 on the conveyance carriage 1, and operating the switching apparatus 30A and 30B switches the standing/ reclining struts l la and 1 Ib accommodated within the accommodating recessed portions 12, that is to say, the fore and aft pairs of standing/reclining struts 1 Ia and 1 Ib of the second supporting means 7A and 7B in a retracted position, into the standing position as shown in Fig. 2 IB. Specifically, as shown in Figs. 13 and 14, the cover plate lifting levers 73 of each of the cover plate opening/closing means 70a and 70b provided on the cover plate opening/closing apparatus 31A and 3 IB are rotated approximately 90 degrees around the left and right horizontal axes 72 by means of the cylinder units 75, switching from the reclining position to the standing position. During the procedure, the cover plate lifting levers 73 are advanced from a space on an underside of the conveyance carriage 1 into the accommodating recessed portions 12 of the conveyance carriage 1, and by means of the rollers 73a of the ends of the cover plate lifting levers 73, the cover plates 12a of each of the accommodating recessed portions 12 are lifted against the resistance of the biasing force of the helical torsion coil springs 12c to open them to the standing position without interfering with the standing/reclining struts l la and l ib.

[0043] When the cover plates 12a are opened, next the movable platforms 61, as shown in Fig. 15-17, are extended from the maximum retracting position to the maximum extending position by means of the cylinder units 66 on the respective switching means 59a and 59b of the switching apparatus 30A and 30B, and thereby the hollow grooved members 62a of the operating bodies 62 standing by in the maximum extending position on the movable platforms 61 are engaged sideways onto the rollers 60a on the end of the operated levers 60 of each of the standing/reclining struts l la and 1 Ib, which are in the reclining position within each of the accommodating recessed portions 12. In this state, by moving the operating bodies 62 from the maximum extending position to the maximum retracting position parallel to the travel path of the conveyance carriage 1 by means of the cylinder units 69, the operated levers 60 of each of the standing/reclining struts 11a and 1 Ib are rotated around the left and right horizontal axes 13 via the hollow grooved members 62a of the operating bodies 62 and the rollers 60a engaged therein. As a result, the respective standing/reclining struts 11a and 1 Ib rotate around the left and right horizontal axes 13 to stand up from the accommodating recessed portions 12, and switch to the standing position, where both the upper ends 14 become adjacent to each other as shown by the imaginary line in Fig. 19.

[0044] When both the upper ends 14 of the fore and aft pairs of standing/reclining struts 11a and 1 Ib abut to each other, both the engaging members 14a are engaged together, as explained above; the fore and aft pairs of standing/reclining struts l la and 1 Ib being in the standing position securely form equilateral triangles when viewed in profile, and as shown in Fig. 2 IB, the supported members 19 (the cylinder 21) of the supports 16A and 16B, being lifted to the lifting level L3 by the elevating apparatus 29 A and 29B, come to rest in a standby state directly above the touching upper ends 14. Therefore, when the elevator bodies 32 of the elevating apparatus 29A and 29B are then lowered by means of the motors 40 of the elevator driving means 33, and the supports 16A and 16B being supported at the lifting level L3 by the supports 50a and 50b of the extendable/retractable slides 39 on the elevator bodies 32 are lowered, since the coupling pins 23 of the coupling means 22 provided on the supported members 19 of the supports 16A and 16B are maintained in a state being disengaged from within the cylinders 21 by means of the coupling pin operating means 51 on the elevator bodies 32 as explained above, the supported members 19 (the cylinders 21) of the descending supports 16A and 16B engage with the interposed upper ends 14 of the fore and aft pairs of standing/reclining struts l la and 1 Ib in the standing position, and thereby supports 16A and 16B are borne by means of the fore and aft pairs of standing/ reclining struts l la and 1 Ib as shown in Fig. 22A.

[0045] Under such a condition, when the extendable/retractable slides 39 on the elevator bodies 32 are retracted to maximum retracting positions on the elevator bodies 32 by means of the cylinder units 49a and 49b, the operating plates 57 of the coupling pin operating means 51 are disengaged laterally from the coupling pins 23 (the small diameter operable shanks 23a) of the coupling means 22 on the supported members 19 of the supports 16A and 16B. Then, the coupling pins 23 advance into the cylinders 21 due to the biasing force of the coil springs 24, and as shown in Fig. 20, penetrate the locking holes 14b of the interposed upper ends 14 of the fore and aft pairs of standing/ reclining struts 1 Ia and 1 Ib engaged within the supported members 19 (the cylinders 21) of the supports 16A and 16B, completely combining the interposed upper ends 14 of both the standing/reclining struts 1 Ia and 1 Ib and the supported members 19 of the supports 16A and 16B into a single integrated whole. [0046] Once the supports 16A and 16B are supported by the upper ends 14 of the fore and aft pairs of standing/reclining struts 11a and 1 Ib of the second supporting means 7 A and 7B in a standing position in the abovementioned manner, as shown in Fig. 22B, the elevator bodies 32 of the elevating apparatus 29A and 29B are lowered to the maximum descending position by means of the motors 40 of the elevator driving means 33; and the hollow grooved members 62a of the operating bodies 62 of the movable platforms 61 are disengaged sideways from the rollers 60a of the operated levers 60 on the sides of the standing/reclining struts 11a and 1 Ib by retracting the movable platforms 61 of each of the switching means 59a and 59b of the switching apparatus 30A and 30B to the maximum retracting position by means of cylinder units 66; and then the cover plate lifting levers 73 of the cover plate opening/closing means 70a and 70b of the cover plate opening/closing apparatus 31A and 3 IB are rotated to be restored to an original reclining position by means of the cylinder units 75, thereby the conveyance carriage 1, where the supports 16A and 16B of the work support platform 15 are supported at the high level by means of the second supporting means 7 A and 7B, can be moved from the work support level switching position.

[0047] It should be noted that the operating plates 57 of the coupling pin operating means 51, at an appropriate time after the extendable/retractable slides 39 on the elevator bodies 32 return to the maximum retracting position, are retracted to the movable bodies 54 by means of the cylinder units 56 and are prepared for the next operation. Further, the operating bodies 62 on the switching means 59a and 59b, after the movable platforms 61 are restored to the maximum retracting position, are also restored to an original extending position by means of the cylinder units 69 and are prepared for the next operation. When the cover plate lifting levers 73 of the cover plate opening/closing means 70a and 70b are restored to the original reclining position, since the cover plates 12a of each of the accommodating recessed portions 12 on the conveyance carriage 1 attempt to close due to the biasing force of the helical torsion coil springs 12c, the cover plates 12a are thereby maintained in a state of being in close contact to each of the standing/reclining struts 11a and 1 Ib in the standing position.

[0048] Within the work support level switching position in the travel path of the conveyance carriage 1, since the positional relationship of each apparatus 19A to 3 IB on the ground and operational parts on the conveyance carriage 1 with the work support platform 15 supported thereon must be correctly and securely maintained, it is necessary to correctly stop the conveyance carriage 1 in a secure position. Consequently, the work support level switching position can be provided with, for example, a conveyance carriage positioning apparatus 76 as shown in Fig. 9. The conveyance carriage positioning apparatus 76 shown in Fig. 9 is provided with a locking piece 77 having an end freely engaging/disengaging with an engaged de- pression disposed in a given position on the underside of the conveyance carriage 1 on the ground side. The locking piece 77 has a medial point rotatably supported around a fore and aft horizontal axis 78, which is parallel with the travel path direction of the conveyance carriage 1 so as to freely stand/recline. A cam 80, which operates the standing/reclining action of the locking piece 77 via a cam follower roller 79 rotatably supported on a lower end of the locking piece 77, is disposed such that it freely moves laterally in a left and right horizontal direction perpendicular to the travel path direction of the conveyance carriage 1. It is arranged such that the conveyance carriage 1 can be locked at a secure position, that is to say, at the work support level switching position, by moving the cam 80 laterally by means of a cylinder unit or other appropriate driving means so as to stand the locking piece 77, and then by engaging the end of the locking piece 77 with the engaged depression on the underside of the conveyance carriage 1 being stopped at the secured position.

[0049] The above-mentioned embodiments describe a case where each apparatus 29A to

3 IB in the work support level switching position transfers the supports 16A and 16B, being supported at the second low level by means of the first supporting means 6A and 6B, to the second supporting means 7 A and 7B supporting the supports 16A and 16B at the high level. However, by being arranged such that the minimum descending position of the elevator bodies 32 are set to a level corresponding with the supports 16A and 16B being supported at the first low level by means of the first supporting means 6 A and 6B, the supports 16A and 16B being supported by means of the first supporting means 6A and 6B at the first low level can also be transferred by means of each apparatus 29 A to 3 IB to the second supporting means 7 A and 7B. Further, each apparatus 29 A to 3 IB in the work support level switching position can also be used in cases to support the work support platform 15 (supports 16A and 16B), being supported at the high level by means of the second support means 7 A and 7B, at the first low level or the second low level by means of the first supporting means 6A and 6B. Industrial Applicability

[0050] The conveyance carriage of the present invention can be used as a means of loading and conveying a vehicle body in an automobile assembly line while gradually changing the support level of the vehicle body according to the different work area heights the conveyance carriage work floor surface for trim work, final work and chassis work.