JPH04257702A - Caster with buffer - Google Patents

Abstract

PURPOSE:To miniaturize a buffer and simplify its construction, and also lower the center of gravity of an unmanned vehicle. CONSTITUTION:A tire fixing housing 12 whose shaft 11 is fixed is rotatably attached to a caster housing 6 which is mounted on a frame 1 through a mounting board 5 and a rotary member 7. A spring 17 is held between a connecting board 14 of the tire fixing housing 12 and a spring case 18 containing the spring 17, and a tire 16 of the tire fixing housing 12 is energized downward by the elasticity of the spring 17. The shaft 11 is braked by an electromagnetic clutch 22 based on the vehicle speed so as to regulate the rotation of the tire fixing housing 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free caster as a driven wheel with a shock absorbing device that follows a driving wheel mounted on an unmanned vehicle, for example.

0002

2. Description of the Related Art Conventionally, as shown in FIG. 9, free casters 41, which can freely change the direction of wheels 40, have been installed as driven wheels that follow the driving wheels of an automatic guided vehicle through a damper mechanism 42. It is known that the same method is used (Japanese Utility Model Publication No. 60-6672). The structure of this damper mechanism includes a mounting plate 4 fixed to the frame 43 of the automatic guided vehicle.
A spring 4 is installed between the caster fixing member 4a and the caster fixing member 44b.
5 has been intervened. A hydraulic cylinder 46 is fixed to the mounting plate 44a within the spring 45, and the lower end of a piston rod 47 protruding from the hydraulic cylinder 46 is attached to the caster fixing member 44b.

[0003]The piston 46 of the hydraulic cylinder 46
Piping 48 is provided so that hydraulic oil can freely flow in and out of the upper and lower chambers of the cylinder 46 partitioned by a, and the hydraulic oil is controlled by a solenoid valve. This damper mechanism 42 reduces the impact exerted on the automatic guided vehicle even if the wheels 40 of the automatic guided vehicle ride on an uneven travel path, for example.

0004

[Problems to be Solved by the Invention] However, since the damper mechanism 42 mounted on the automatic guided vehicle is mounted separately from the free casters 41, the device becomes larger, and the structure is also limited to the hydraulic cylinder 46, piping, etc. 48 and solenoid valve 4
It is complicated because it uses 9 mag. Further, since the distance from the wheels 40 of the free casters 41 to the frame 43 is long, there is a problem that the height of the automatic guided vehicle is high, that is, the center of gravity is high.

The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the size of the shock absorber, simplify the structure, and further lower the center of gravity of an unmanned vehicle. The purpose is to provide caster.

[0006]

[Means for solving the problem] In order to achieve the above purpose,
The present invention includes a caster housing attached to a vehicle body frame, a shaft rotatably attached to the caster housing, a tire fixing housing plate fixed to the shaft, and a connection between one end of the tire fixing housing plate and the caster housing. Equipped with a shock absorbing device consisting of an elastic member provided between one end of the tire fixing housing plate, a wheel attached to the other end of the tire fixing housing plate, and a braking means provided on the caster housing that applies braking to the shaft based on the vehicle speed. Its gist is caster.

[0007]

[Operation] The elastic member provided between one end of the tire fixed housing plate and one end of the caster housing absorbs vibrations etc. from the traveling path. Further, for example, when the shaft is stopped at a predetermined position, if the shaft cannot be rotated by the braking means, the elastic force of the elastic member will not work. As a result, nose-down (a state in which the front of the vehicle sinks) caused by inertial force during braking is prevented.

[0008]

[Embodiment] An embodiment in which the present invention is embodied in an automatic guided vehicle will be described below with reference to FIGS. 1 to 8. 4 and 5 show an automatic guided vehicle M traveling along a guide line L, and a pickup coil 2 for detecting the guide line L is attached to the bottom front side of a frame 1 thereof. Also, the same frame 1
A pair of left and right drive wheels 3 constituting a steering mechanism and a traveling mechanism are provided at the center of the bottom surface of the vehicle. Furthermore, casters 4 with shock absorbers as driven wheels that follow the driving wheels 3 are mounted on both front, rear, right and left sides of the bottom surface of the frame 1.

As shown in FIGS. 1 to 3, the casters 4 with shock absorbers are fixedly attached to the bottom of the frame 1, and a cylindrical rotary member 7 is rotatably attached to the mounting plate 5. It is worn. A slip ring 7a for electrically connecting an electromagnetic clutch 22 and a controller 24, which will be described later, is attached to the rotating member 7. Further, a caster housing 6 made of a metal plate bent into a substantially reverse concave shape is connected and fixed to the lower surface of the rotating member 7 with bolts. An extending portion 6b is formed extending from one end side of both side plates 6a of the caster housing 6, and a support plate 10 having a bolt insertion hole 9 therethrough is connected and fixed between the upper portions of both extending portions 6b. .

A shaft 11 is rotatably attached between the two side plates 6a, and a portion of the shaft 11 protrudes outward from one of the side plates 6a. A pair of left and right tire fixing housings 12 made of bent metal plates are fixed to the shaft 11. A tire 16 is rotatably held between the left and right ends of the pair of left and right tire fixing housing plates 12. On the other hand, a connecting plate 14 is connected and fixed between the upper ends of the pair of left and right tire fixing housing plates 12 so as to face the support plate 10, and the connecting plate 14 has bolt insertion holes corresponding to the bolt insertion holes 9. 15 is provided transparently.

A spring case 18 housing a spring 17 is disposed below the connecting plate 14, and a bolt insertion hole 19 corresponding to the bolt insertion holes 9 and 15 is transparently provided at the bottom of the spring case 18. . Then, the bolt 20 is passed through the connecting plate 14 and the support plate 10 from the bolt insertion hole 19 on the bottom surface of the spring case 18 through the insertion holes 15 and 9, and the nut 20 is inserted into the bolt 20 on the upper surface of the nut support plate 10. are screwed together. That is, the spring case 18 is supported by the support plate 10, and the spring 17 is held between the bottom of the spring case 18 and the lower surface of the connecting plate 14. Then, due to the elastic force of this spring 17, the tire fixing housing plate 12,
That is, the tire 16 is always urged clockwise around the shaft 11. Note that the amount of clockwise rotation of the tire fixing housing plate 12 is regulated by the contact between the lower surface of the nut support plate 10 and the upper surface of the connecting plate 14.

As shown in FIGS. 1 and 2, the shaft 11
An electromagnetic clutch 22 is fixedly attached to the side plate 6a on the protruding side, and the electromagnetic clutch 22 is excited and controlled to control the amount of connection (closed amount) between the shaft side clutch plate and the side plate side clutch position. The shaft 11 is made rotatable or non-rotatable relative to the side plate 6a. In this embodiment, the excitation control of the electromagnetic clutch 22 is performed by chopper control, and the excitation current in the chopper control is supplied from the controller 24 via the cord 23 and the slip ring 7a provided in the rotating member 7. .

Next, the electrical configuration of the automatic guided vehicle M equipped with this shock absorbing caster 4 will be explained based on the block diagram of FIG. The in-vehicle controller 24 is composed of a CPU 25 that performs operation control, a ROM 26 that stores control program programs, etc. in advance, and a RAM 27 that temporarily stores calculation results of the CPU 25.
The travel processing operation of the automatic guided vehicle M is executed according to the control program stored in the controller 26. In addition, the same automated guided vehicle M
The vehicle speed sensor 28 mounted on the automatic guided vehicle M detects the vehicle speed of the automatic guided vehicle M, and sends the detection signal to the input/output interface 29.
It is designed to output to the CPU 25 via.

As shown in the map of FIG. 7, the ROM 26 stores in advance the amount of closing of the clutch plate of the electromagnetic clutch 22 with respect to the vehicle speed of the automatic guided vehicle M as target closing value data, and the CPU 25 receives data from the vehicle speed sensor 28. A chopper controlled current corresponding to the target opening value for the input vehicle speed is output to the electromagnetic clutch 22 via the input/output interface 30. And CPU25
is designed to calculate and output the chopper control current so that the target closing value of the electromagnetic clutch 22 becomes smaller in proportion to the vehicle speed of the automatic guided vehicle M based on the target closing value data shown in the map of FIG. . Therefore, when the vehicle speed is zero, the target closing value is maximum, that is, the shaft 11 is made unrotatable with respect to the side plate 6a, and the elastic force of the spring 17 does not act on the tire 16. As the vehicle speed increases, the target closing value becomes the maximum. If the value is small, that is, the elastic force of the spring 17 gradually increases
Started working at 6.

[0015] Therefore, since the damping force against vibration of the caster 4 is controlled to increase in proportion to the vehicle speed,
While the automatic guided vehicle M is traveling, even if it is constantly subjected to various shocks due to unevenness on the travel path, the closing value of the clutch plate is small, so the elastic force of the spring 17 works against it, causing vibrations. This prevents shock and impact from being transmitted to the vehicle body. Further, when the automatic guided vehicle M arrives at a cargo storage area and stops, the amount of closing of the clutch plate is increased, a brake is applied to the shaft 11, and the elastic force of the spring 17 is no longer activated.

As described above, according to this embodiment, when the automatic guided vehicle M is normally traveling, each part of the automatic guided vehicle M is In addition, when braking the automatic guided vehicle M, the rotation of the tire fixing housing plate 12 is restricted by the electromagnetic clutch 22, and the nose down (
This prevents the front of the vehicle from sinking. Of course, it is also possible to prevent nose-up (lifting of the front of the vehicle) that occurs during oscillation.

Furthermore, in the past, a damper mechanism 42 as a shock absorbing device was provided separately from the free casters 41, resulting in a high vehicle height of the automatic guided vehicle, but according to this embodiment, the shock absorbing device is Since it is attached to the lower side of the caster housing 6 and the tire fixing housing plate 12, the height of the casters can be lowered, and the vehicle height can be lowered. Further, the shock absorber of this embodiment has a spring 17 and an electromagnetic clutch 22.
etc. and does not use a hydraulic circuit, the structure is simplified and costs can be reduced. Further, since the electromagnetic clutch 22 and the CPU 25 are connected via a slip ring, there is no fear that the cord 23 of the electromagnetic clutch 22 and the cord of the CPU 25 will be cut even if the caster housing 6 is rotated many times.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but may be configured as follows without departing from the spirit of the invention. (1) In the above embodiment, the data pre-stored in the ROM 26 is configured so that the target closing value is calculated step by step with respect to the vehicle speed, as shown in the map of FIG. As shown in FIG. 8, the target closing value may be continuously calculated with respect to the vehicle speed.

(2) In the above embodiment, a total of four casters 4 with shock absorbers are installed as driven wheels of the automatic guided vehicle M, one each on the front, rear, left and right sides, but the number of casters 4 with shock absorbers used is It may be increased or decreased arbitrarily depending on the conditions of use.

[0020]

[Effects of the Invention] As detailed above, according to the present invention, the shock absorber can be miniaturized, the structure can be simplified, and the vehicle body can be stabilized when the unmanned vehicle is running or stopped. play.

[Brief explanation of the drawing]

FIG. 1 is a side view of a caster with a shock absorber.

FIG. 2 is a front view of a caster with a shock absorber.

FIG. 3 is a side sectional view of a caster with a shock absorber.

FIG. 4 is a side view of the automatic guided vehicle.

FIG. 5 is a plan view of the automatic guided vehicle.

FIG. 6 is a block diagram showing the electrical configuration of the automatic guided vehicle.

FIG. 7 is a map showing the relationship between the target closing value and the vehicle speed stored in advance in the ROM.

FIG. 8 is a map showing the relationship between the target closing value and the vehicle speed, which is stored in advance in a ROM in another example.

FIG. 9 is a side sectional view of a caster equipped with a damper mechanism showing the prior art.

[Explanation of symbols]

3 Drive wheel 4 Caster 17 with shock absorber as a driven wheel
Spring 22 Electromagnetic clutch 25 CPU as switching control means 26 ROM 28 Vehicle speed sensor M as vehicle speed detection means Automatic guided vehicle as unmanned vehicle

Claims (1)

[Claims] 1. A caster housing attached to a vehicle body frame, a shaft rotatably attached to the caster housing, a tire fixing housing plate fixed to the shaft, and a tire fixing housing plate attached to the tire fixing housing plate. an elastic member provided between one end and one end of the caster housing; a wheel attached to the other end of the tire fixing housing plate; and a brake provided on the caster housing that applies braking to the shaft based on vehicle speed. A caster with a shock absorbing device consisting of means.