Truck apparatus

The present invention relates to a truck apparatus which may be used in transferring materials in factories, storehouses, etc.

It is known from DE-A-2908199 to provide a truck having a plurality of support wheels and guide wheels rotatably attached to the truck, support means, disposed along a line of travel for the truck, for supporting the truck to vertically and horizontally guide the truck along the line of travel by engaging with the support wheels and guide wheels, the support means comprising a support rail member for supporting and vertically guiding the support wheels a horizontal guide rail member for horizontally guiding the guide wheels by contacting the guide wheels, and drive means for driving the truck along the line of travel.

Figures 1 to 3 illustrate another typical example of the prior art truck apparatus, in which reference numeral 1 designates a supporting frame disposed along a line of travel of a truck 6. The supporting frame 1 has parallel rails 2 and 3 mounted on it along the line of travel. Further, the supporting frame 1 is provided on its top with a primary unit 4 of a linear induction motor and with a primary unit 5 of an electromagnetic brake. The number and positions of the units 4 and 5 are determined to correspond to stations where materials are loaded and unloaded to the truck 6. The truck 6 has substantially a channel shape with its inside directed downwards. It has pairs of support wheels 7 and guide wheels 8 rotatably attached to it and brought into contact with the rails 2 and 3 so that the truck 6 is movable along the line of travel. The truck 6 is provided with a conductor member 9 as a secondary unit of the linear induction motor and with an iron plate 10 of a secondary unit of the electromagnetic brake. The truck 6 further has a split plate 11. One rail 12 has a speed sensor 12 mounted on it. The speed sensor 12 is a photodetector detecting slits of the slit plate 11 for generating signals representing the speed of the truck 6. On the other hand, the other rail 3 has a position sensor 13 which is a reflection-type photosensor for detecting the position of the truck 6. With such a construction, the truck 6 is accelerated or decelerated with the linear induction motor by providing a thrust to the secondary unit 9 of the linear induction motor from the primary unit 4 thereof. The truck 6 is stopped by attracting the secondary plate 10 with the primary unit 5 of the electromagnetic brake. In these events, an electronic control unit (not shown) controls the movement of the truck 6 by controlling supply of power to the primary unit 4 and 5 according to signals from the speed sensor 12 and the position sensor 13.

Since the linear induction motor and the electromagnetic brake as drive units are bolted to the supporting frame 1 and since sensors 12 and 13 are also bolted to the rails 2 and 3, the prior art truck apparatus has the following disadvantages. Firstly, in adding another station or changing the position of a station already built, additional attaching bolts for bolt joint of primary units of the induction motor and the electromagnetic brake must be formed in the frame 1. Secondly, it is laborious to adjust the positions of the speed sensor 12 and the position sensor 13 relative to the position of the primary unit 4 of the linear induction motor according to a travel pattern of the truck 6. Thirdly, the supporting frame 1 is required to have rather high rigidity since it is subjected to reactions due to electromagnetic force exerted from drive units, i.e., the primary units 4 and 5, on the truck. Lastly, mounting mechanisms of the drive units, such as attaching holes for bolts, must have a rather high accuracy in position and size since relative positions of the rails 2 and 3 and the primary units 4 and 5 must be held at a rather high degree.

Accordingly, it is an object of the present invention to provide a truck apparatus which is less laborious in installing additional drive units or in changing the positions of the drive units already disposed than the prior art truck apparatus.

It is another object of the present invention to provide a truck apparatus in which the supporting frame of the truck is required to have rather less rigidity than the prior art truck apparatus.

A still another object of the present invention is to provide a truck apparatus which is required to have rather smaller accuracy in forming mounting mechanisms of the drive units than the prior art apparatus.

According to the present invention there is provided a truck apparatus comprisig a truck having a plurality of support wheels and guide wheels, both wheels being rotatably attached to the truck; support means, disposed along a line of travel of the truck, including a support rail member for supporting and vertically guiding the support wheels and a horizontal guide rail member for horizontally guiding the guide wheels by contacting the guide wheels and drive means for driving the truck along the line of travel characterised in that the drive means is mounted on the support means so that the drive means is slidable and can be fixed to the support means in any position along the line of travel.

Reference is now made to the accompanying drawings, in which:

• Figure 1 is a fragmentary plan view of a conventional truck apparatus with a truck omitted;
• Figure 2 is a front view partially cutaway of the conventional truck apparatus of figure 1;
• Figure 3 is a fragmentary side-elevational view of the conventional truck apparatus of figure 1;
• Figure 4 is a front view partially cutaway of a truck apparatus according to the present invention;
• Figure 5 is an enlarged cross-sectional view of a rail of figure 4;
• Figure 6 is a fragmentary plan view of the truck apparatus of figure 4 with the truck and sensors omitted;
• Figure 7 is an enlarged perspective view of a slit plate and the bracket holding the speed sensor of figure 4
• Figure 8 is a side-elevational view of a shock absorber mounted on opposite ends of the rail of figure 4; and
• Figure 9 is a cross-sectional view of a portion of a modified form of the rail in Figure 5.

Detailed Description of the Preferred Embodiments

In Figures 4 to 9, parts in Figures 1 to 3 are designated by like reference numerals and thus description thereof are omitted.

Figure 4 shows a preferred embodiment of the present invention having a rail 20 as supporting means which may be produced by extrusion of metal such as an aluminum alloy. The rail 20 is disposed along the line L (see Figure 6) of travel of the truck 6, and has a tubular horizontal guide rail 40 which includes a pair of parallel side walls 41 and 42 each having a top end 43, and a top wall 44 bringing the top ends 43 of the side walls 41 and 42. The side walls 41 and 42 have guide surfaces 41 a and 42a respectively. The guide surfaces 41 a and 42a horizontally guide the guide wheels 8 of the truck 6 by contacting the guide wheels 8. As shown in Figure 5, the top wall 44 has a pair of first engaging grooves 21 and 22 formed in the opposite peripheries thereof, so that the grooves 21 and 22 extend along the line L of travel. The grooves 21 and 22 each have an inverted T-shaped cross-section and a pair of first engaging walls 45 defining an opening thereof. Into each of grooves 21 and 22 a head 23a of a bolt 23 slidably fits, and the rear face 23c of the head 23a is brought into engagement with the engaging walls 45 when the end portion 23b of the bolt 23 is attached to the drive unit 25 threadedly engaging with a nut 24. In this embodiment, the drive unit 25 has a mount plate 26 on which the primary unit 4 of the linear induction motor and the primary unit 5 of the electromagnetic brake are mounted. As illustrated in Figure 6, the mount plate 26 has two pairs of notches 46 formed in the oppposite ends thereof so that the end portion 23b of a corresponding bolt 23 passes through each notch 46. The plate 26 is fastened to the horizontal guide rail 40 with four pairs of bolts 23 and nuts 24 although only two pairs thereof are shown in Figure 6.

Returning to Figure 4, the rail 20 further has a pair of support rails 27 and 28 integrally formed with respective side walls 41 and 42 of the horizontal guide rail 40. The support rails 27 and 28 have support surfaces 27a and 28a respectively. The support surfaces 27a and 28a support and guide the support wheels 7 by contacting the support wheels 7. The support rails 27 and 28 have second engaging grooves 29 and 30 respectively (see Figure 5). The second grooves 29 and 30 are formed in the peripheries of the support rails 27 and 28 respectively, so that the grooves 29 and 30 extend along the line L of travel. The grooves 29 and 30 each have an inverted T-shaped cross-section and a pair of second engaging walls 47 defining an opening thereof. Into one second groove 29 a head 48a of a bolt 48 fits, and the end portion 48b of the bolt 48 is attached to a bracket 32 holding the speed sensor 12 (see Figure 7) thereon by threadedly engaging with a nut 31. THus, the rear face 48c of of the head 48a is brought into engagement with the engaging walls 47 in the same manner as the rear face 23c of the head 23a of the bolt 23 brought into engagement with the walls 45. On the other hand, into the other second groove 30 a head 49a of a bolt 49 fits, and the end portion 49b of the bolt 49 is attached to a bracket 33 holding the position sensor 13 thereon by threadedly engaging with the nut 34. Thus, the rear face 49c of the head 49a is brought into engagement with the engaging walls 47 of the groove 30 in the same manner.

As further seen in Figure 8, the rail 20 is provided on its opposite ends with shock absorbers 35. Each shock absorber 35 has a bracket 38 fastened to the horizontal guide rail 40 by means of bolts 36 attached to the engaging walls of 45 of the first engaging grooves 21 and 22 with nuts 37 as in the same manner as the mount plate 26.

Figure 9 shows a modified form of the first grooves 21 and 22 in which first engaging groove 50 has an L-shaped cross-section so that an L-shaped engaging member 51 fits to the groove 50. The second engaging grooves 29 and 30 may also have an L-shaped cross-section.

The drive unit 25, the speed sensor 12 and the position sensor 13 are slidable on the rail 20 by loosening the threaded connection between bolts and nuts, which fasten them on the rail 20, and may be remounted to desired positions on the rail 20 by retightening the bolt-and-nut connection. Thus, it is possible to install additional drive units and sensors or to change and to adjust the positions of the drive unit 25 and so on already mounted without forming additional attaching holes in the rail 20. Although a pair of parallel rails of the conventional apparatus must have their distance adjusted when they are mounted on the frame 1, no such adjustment is necessary in the present invention. It is also unnecessary to adjust the space between the drive unit 25 and the truck 6, since the drive unit 25 is fastened to the rail 20. Furthermore, the supporting frame 1 of the truck apparatus according to the invention is required to have less rigidity than that of the conventional one, because it is subjected to less reactions due to electromagnetic force exerted from the drive unit 25 on the truck 6.