GB2112548A - Wheel speed control apparatus of vehicles running along two rails - Google Patents

Abstract

In wheel speed control apparatus for a vehicle having a plurality of wheels rolling along two spaced parallel rails 11, 12 a frame structure supporting the wheels such that they can move relatively, the apparatus comprising a wheel driver 46 controlling drive of at least one wheel, there are provided at least two detectors 31, 32 for measuring distances between the detectors and a reference surface extending in parallel with the rails 12R, the detectors being disposed to oppose at least one rail and mounted on the frame structure at points spaced apart in a longitudinal direction thereof, circuit means 35 for obtaining a difference in the distances measured by the detectors, and a controller which operates when the difference exceeds a predetermined value, for controlling the wheel driver(s) so as to decrease the difference to a value less than the predetermined value. <IMAGE>

Description

SPECIFICATION Wheel speed control apparatus of vehicles running along two rails This invention relates to apparatus for controlling the speed of wheels of a vehicle running along two rails.

In a vehicle of the type described above, for exam ple, a crane, a reclaimer, a stacker or the like, the rolling speeds of the left and right side wheels become different by a certain cause so that both wheels do not run in parallel with respective rails. As a consequence, the vehicle performs a wavy motion or derails, thus causing an accidental fault.

For this reason, the wheels are provided with flanges or means for synchronizing the rolling speeds of the left and right side wheels has been provided. The prior art devices can be classified into the following four types.

(1) A mechanical synchronizing system in which two gear racks are installed in parallel with the two racks and pinions engaging the racks are provided for the vehicle with the shafts of the pinions interconnected.

(2) Equal rotation synchronizing system in which left and right side wheels are coupled together to cause then to rotate at the same number of revolutions.

(3) A synchronizing system wherein the number of revolutions of the left and right side wheels are detected directly or indirectly so as to match the number of revolutions of the left and right side wheels.

(4) Absolute position detection synchronizing system in which the absolute running positions of the left and right side wheels are detected and the speeds of the two wheels are adjusted so as to match the detected absolute running positions.

Each of these systems has inherent advantages and disadvantages. More particularly, with the system (1), the most accurate synchronization can be obtained, but this system is expensive because it is necessary to install gear racks. Although the system (2) is the simplest, the running distances between the left and right side wheels are caused to become different due to a small difference in the diameters of the two wheels and slips between the wheels and the rails. This results in a wavy motion of the vehicle when such wavy motion apparatus once, it is difficultto restore the normal running attitude due to inertia.Like system (2), in the system (3) too, the running distances of the two wheels become different due to difference in the diameters of the wheels and slips between the wheels and the rails, and such difference in the running distances accumulate to such an extent to disenablesynchronous running.

The accuracy of the system (4) becomes different according to the method of detecting the absolute positions. Thus, when the positions are detected by a contact type device, the synchronization performance is affected by the difference in the peripheral length of the contact pieces, frictions and slips, whereas when the positions are detected by noncon tacttype devices, although synchronization can be obtained in the same manner as in the system (1) as it is necessary to install output terminals throughout the length of the rails, the installation cost is increased.

It is therefore an object of this invention to provide a novel apparatus capable of controlling wheel speeds of a vehicle running along two rails without installing rack rails but only requires addition of simple component elements.

According to this invention, there is provided wheel speed control apparatus for a vehicle having a plurality of wheels respectively rolling along two spaced parallel rails, a frame structure supporting the wheels such that they can move relatively, the apparatus comprising a wheel driver controlling drive of at least one wheel, characterized in that there are provided at least two detectors for measuring distances between the detectors and a reference surface extending in parallel with the rails, the detectors being disposed to oppose at least one rail and mounted on the frame structure at points spaced in a longitudinal direction thereof, means for obtaining a difference in the distances measured by the detectors, and means, which operates when the difference exceeds a predetermined value, for controlling the wheel drivers so as to decrease the difference to a value less than the predetermined value.

In the accompanying drawings: Fig. 1 is a perspective view showing the basic construction of a vehicle equipped with wheel speed control apparatus embodying the invention; Fig. 2 is a block diagram showing one embodiment of the wheel speed control apparatus utilized in the vehicle shown in Fig. 1; Fig. 3 is a plan view showing a positional relationship between a reference surface and a detector, with a frame removed, Fig. 3 being useful to explain the operation of the wheel speed control apparatus of this invention; Figs. 4A and 4B show operations of modified detectors utilized in this invention; Figs. 5A and 5B show still other modifications of the detector utilized in this invention; Figs. 6A - 6C and Figs. 7A - 7F show modified constructions of the vehicle; and Figs. 8 and 9 show modified constructions of the wheels of the vehicle.

Figs. 1, 2 and 3 show one embodiment of the wheel speed control apparatus according to this invention as applied to avehicle of a plain type construction. As shown, the vehicle 10 comprises wheel frames 18 and 19 respectively having wheels 13, 14 and 15, 16 rolling along spaced parallel rails 11 and 12, and a main frame 22 interconnecting the wheel frames 18 and 19 through a stationary hinge 20 and a pin 21. The wheel frames 18, 19 and the main frame 22 constitute a plain H type strucutre. Each rail has an I shaped cross-sectional configuration and fastened to a concrete bed or ground surface 25 by well known means. Since the construction of the vehicle 10 described above is well known in the art, detailed description thereof will not be made herein.

In the vehicle 10, the side wall 12R of the head of the rail 12 is utilized as a reference surface which operates in a manner to be described hereunder. Normally, the side wall 12R extends in parallel with the direction of installing the real 12 and provides a smooth flat surface. Two detectors 31 and 32 are mounted on the wheel frame 19 at positions of the reference surface, a predetermined distanced spaced apart in the horizontal direction. When the wheels 15 and 16 correctly ride on the rails, that is when the axes of the wheels 15 and 16 cross perpendicularly with phontom lines T (that is reference lines 19R) extending in the directions of rails at the centers of respective wheel frames 18 and 19 the detectors are correctly positioned. These detectors 31 and 32 are mounted close, as far as possible, to respective wheels 15 and 16.In this example, the detectors are mounted on the ends of inverted L shaped arms 33 and 34 which extend forwardly and rearwardly from a side surface of the frame 19.

The detectors31 and 32 supported by the arms 33 and 34 are in the form of ultrasonic transmitters. The ultrasonic transmitter is reflected by the reference surface 12R and then received by a receiver, not shown. The distance between the detector and the reference surface is determined by an interval between transmission of ultrasonic wave from the transmitter and reception of the wave by the receiver. The method of determining the distance from the interval described above is well known in the art and can be obtained by a digital processing or an analog processing. In the following description, for the purpose of simplicity it is assumed that each detector transmits an analog voltage signal corresponding to the interval described above.

As shown in Fig. 2, the output signals of the detectors 31 and 32 are applied to a differential detector, i.e., a subtractor40 of control device 35 to obtain the difference therebetween. The output signal Vs of the subtractor40 is applied to a (+) inputterminal of a comparator 41 and to a (+) input terminal of another comparator 42 via an inverter43. A (-) inputterminal of the comparator 41 is supplied with a reference value VR1. As a consequence, the comparator 41 compares Vs with VR1 and when the former issmal- let than the latter, it will not produce an output, whereas when is becomes larger than VR1, the comparator 41 sends a control signal CS1 to a controller 44.While the inverter output Vs supplied th rough the inverter43 is smaller than a reference value VR2, the comparator 42 does not produce any output signal, whereas when Vs becomes larger than VR2 the comparator 42 sends a control signal CS2 to the controller 44.

When supplied with either one of the control signals CSI and CS2, the controller 44 sends a speed change signal to the wheel drivers 44 and 45 for driv ing the wheels 14 and 16 of respective frames 18 and 19, whereby the wheel drivers 44 and 45 operate upon wheels 14 and 16 such that the output Vs of the differential detector 40 will become to zero. In this case, the wheel drivers 44 may be arranged such that they simultaneously actuate other wheels 13 and 15 of the same frame.

The operation of the apparatus of this invention will be described hereunder with reference to Fig 3.

Where the frame 19 ofthevehicle 10 is in perfect parallel relation with rail 12 and where the reference line 19R of the frame and the rail are contained in the same vertical plane, the output signals produced by the detectors 31 and 32 would have the same magnitude so that the output of the subtractor46 is substantially zero and the comparators 41 and 42 do not produce outputs CS1 and CS2.

However, when the vehicle 10 assumes an attitude in which the reference line 19R of the frame 12 makes an angle o with respect to the side wall of rail 12, that is the reference surface 12R, the distances between the detectors 31 and 32 and the side wall of the rail 12, that is the reference surface 12R become different. Thus, the horizontal distance dl, between the detector 31 and the reference surface 12R becomes shorter than the horizontal distance d2 between the detector 32 and the reference surface 12R. Consequently, the output of the subtractor40 becomes a limited value of +Vs1, for example. When this output +Vs1 is larger than VR1,the comparator 41 produces the control signal CS1.Production of this signal CS1 means that the wheels 13 and 14 on the frame 18 of the vehicle 10 are lagged with respect to the wheels 15 and 16 on the frame 19.

Then, the controller 44 sends a speed change signal SCS1 to the wheel driver 45 to apply a braking force upon the wheel 16 (or 16 and 15). This braking operation is continued until the output Vs1 of the substractor 40 becomes smaller than VR1 so as to stop sending out of the control signal CS1.

In this case, the controller 44 may be constructed such that it sends a speed change signal SCS2 to the wheel driver 45 to accelerate the wheel 14 (or 14 and 13). The controller 44 may apply a braking force to wheel 16 (or 16 and 15) via the wheel driver 44 while at the same time accelertes the wheel 14 (or 14 and 13) through the wheel driver 45. These methods are determined in accordance with the construction of the vehicle 10 or other design conditions.

Conversely, when the wheels 13 and 14 on the frame 18 of the vehicle lead with resepct to the wheels 15 and 16 on the frame 19, the distance dl between the detector 31 and the reference surface 12R would become longer than the distance d2 between the detector 32 and the reference surface 12R with the result that the subtractor 40 outputs an output signal -Vs. In response to this negative output voltage, the comparator 42 operates to compare the output of the inverter 43 with the reference voltage VR2.As the output of the inverter 43 becomes larger than the reference voltageVR2 a control signal CS2 is sent to the controller 44 and the controller 44 sends control signal SCSI or SCS2, or SCS1 and SCS2 to wheel drivers 45 or 46, or 45 and 46 such thatthevoltage -Vs becomes substantially zero, that isthe distance d2 between the detector 32 and the reference surface 12R would become substantialty equal to the distance dl between the detector 31 and the reference surface 12R.

According to the control apparatus of this invention, the distances between respective detectors and the reference surface are constantty measured, and each time when the difference in the measured distances exceeds a predetermined value an operation for correcting the difference is performed at once.

This means that there is no appreciable time lag between the detecting operation and the control or correction operation. Consequently, the vehicle can move smoothly over the entire running range with out any wavy motion or derailment.

Although in the foregoing embodiment the differ ence in the distances between respective detectors 31 and 32 and the reference surface was determined directly, the invention is not limited to the measurement of horizontal distances. In other words, it is only necessary to measure the distances between the detectors and the reference surface. Since the distance between two detectors is known, when the distances between the detectors 31 and 32 and the reference surface 1 2R are determined, the deflection angles 8 and and &commat;' between the frame and the reference surface can be determined as shown in Figs. 4A and 4V. Forthis reason, the deflection angles 8 and 0' can be used as the outputs of the detectors.

Figs. 5A and 5B show modifications of this invention, that is modified detectors that can be substituted for the ultrasonic detectors described above. In the modification shown in Fig. 5A, the horizontal movement of a detection rod 54 extending from a supporting frame 52 of rollers 51 which normally contact the reference surface 12R is detected, and the variation of the movement is detected by an angle detector 56 provided at one end of the detection rod 54 apart from the reference surface 12R. The modification shown in Fig. 5A further comprises a hollow cylindrer 60 supported by the frame 19 of the vehicle 10 through a support 58, a sleeve 61 for guiding the detection rod 54, washers 63 and 64 and a spring 65 disposed between these washers.

The modification shown in Fig. 5B comprises a differential transformer 74 constituted by a horizontal reference surface 12R extending in parallel with the rail 12 and made of metal, preferably magnetic material and a pair of electrodes or coils 71,72 disposed on the opposite sides of the reference surface 12R and secured to a suitable portion of the vehicle 10.

With this construction, the output of the differential transformer 74 varies according to the length of the reference surface 12R entering between the pair of coils or electrodes 71 and 72. The signals outputted from the modified detectors shown in Figs. 5A and 5B are processed in the summer as in the previous embodiment utilizing a supersonic transmitter.

Although not shown, other well known distance measuring devices, for example those utilizing light, and capacitance variation can also be used.

The rails along which the wheels roll are not limited to the rails having I shaped cross-sectional configuration and rails having rectangular or circular cross-sectional configuration, wires, T shaped steel bars, grooved steel bars, flat steel bars or member having any desired shape can be used so long as the wheels can roll along the rails.

Further, the vehicle 10 or the movable body is not limited to those illustrated hereinbefore. For example, flat structures shown in Figs. 6A, 6B and 6C or structures having various shapes as shown in Figs.

7A through 7F can also be used. The vehicle shown in Fig. 6A has both frames coupled to the main frame with stationary hinges. The vehicle shown in Fig. 6B has both frame coupled to the main frame with pins, whereas that shown in Fig. 6C has two side frames secured to the main frame, but one side frame has only one wheel, thus constituting a structure supporting at3 points.

Fig. 7A shows an overhead travelling crane, Fig.

7B a gate shaped structure, Fig. 7C an arch shaped structure, Fig. 7E a structure riding on rails at different ievels, and Fig. 7F a carriage structure. The structures shown in Figs. 7B, 7C, 7E and 7F are used as stackers, those shown in Figs. 7B, 7C, 7D and 7E are used as reclaimers, and that shown in Fig. 7F is used as a carriage. In each structure, by merely using some additional component parts the wavy motion of the vehicle can be prevented.

In all of the foregoing embodiments only one wheel is mounted at one point of each frame, but a plurlity of wheels may be provided at each point as shown in Fig. 8.

To increase the running stability of the vehicle, as shown in Fig. 9, guide rollers 80 and 81 may be disposed close to both sides of the rail 12. This construction is particularly effective where wheels having no flanges are used. It will also be understood that only one guide roller is effective.

Further, of the wheels rolling on two rails, at least two wheels on different rails which oppose to each other over the rail span may each be provided with an interior (with respect to the rail) guide roller, an exterior guide roller or interior and exterior guide rollers in combination.

It is further understood by those skilled in the art that the foregoing description is a preferred embodiment of the disclosed device and that various changes and modifications may be made in the invention without departing from the spirit and scope thereof.

Claims (10)

1. In wheel speed control apparatus for a vehicle having a plurality of wheels respectively rolling along two spaced parallel rails, a frame structure supporting said wheels such that they can move relatively, said apparatus comprising a wheel driver controlling drive of at least one wheel, the improvement which comprises at least two detectors for measuring distances between said detectors and a reference surface extending in parallel-with said rails, said detectors being disposed to oppose at least one rail and mounted on said frame structure at points spaced in a longitudinal direction thereof, means for obtaining a difference in the distances measured by said detectors, and means, which operates when said difference exceeds a predetermined value, for controlling said wheel drivers so as to decrease said difference to a value less than said predetermined value.

2. The apparatus according to claim 1 wherein said reference surface comprises a side surface of one rail.

3. The apparatus according to claim 1 wherein said difference is expressed by a deviation angles of said vehicle with respect to said reference surface.

4. The apparatus according to claim 1 wherein said means for obtaining the difference comprises a subtractor producing a difference between output signal of said two detectors, a comparator compar ing an output signal ofsaidsubtractorwith said predetermined value, and a controller controlling said wheel driver in accordance with an output signal of said comparator.

5. The apparatus according to claim 1 wherein each detector comprises a supersonic transmitter.

6. The apparatus according to claim 1 wherein each detector comprises a roller in contact with said reference surface, a rod pivotally supporting said roller, a support slidably supporting said rod and mounted on said vehicle, and a converter for converting a quantity of movement of said rod into an electric signal.

7. The apparatus according to claim 1 wherein each detector comprises a differential transformer arranged to accommodate said reference surface and supported by said frame structure.

8. The apparatus according to claim 1 which further comprises at least one guide roller opposing a side surface of one rail.

9. Wheel speed control apparatus incorporating an arrangement substantially as described herein with reference to Fig. 2 of the accompanying drawings.

10. Wheel speed control apparatus as claimed in claim 1, incorporating arrangements substantially as described herein with reference to Figs. 1 and3, Figs.

4A and 4B, Figs. 5A and 5B, Figs. 6A-6C, Figs. 7A-7F or Figs. 8 and 9 of the accompanying drawings.