JPH046593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering system for a four-wheeled vehicle.

In a typical vehicle, the two wheels at one end (usually the rear end) are rotatably mounted but not steerable, and the wheels at the other end (usually the front end) are mounted rotatably and steerably. When steering a vehicle to the left or right, both front wheels are steered in the same direction, causing the vehicle to turn around a point on an extension of the rear wheel axis. This point is far from the vehicle and increases its turning radius. In order to obtain high maneuverability, the turning radius of the vehicle should be zero, and when the vehicle turns left, the left rear wheel,
When turning to the right, it is necessary to turn around the right rear wheel.

In this case, in order to avoid dragging or slipping of the front wheels while the vehicle is turning, the amount of steering of both front wheels must be different. Ideally, each front wheel should be steered at right angles to a line from the center of the turn to the center of the front wheels.

In conventional steering mechanisms using lever arms, bell cranks, tie rods, or links, the steering force increases as the wheels are steered from neutral. This steering force becomes extremely large as the turning radius approaches zero.

In view of the above-mentioned circumstances, the present invention makes it possible to make the turning radius zero by varying the amount of turning of both steered wheels, and also prevents the tires from being dragged significantly or the steering force from becoming excessive. An object of the present invention is to provide a steering system for a vehicle.

The present invention is designed to achieve the above object with a simple configuration without causing the above-mentioned problems.

In other words, the steering system for a four-wheeled vehicle of the present invention includes steering columns for each front wheel, eccentric sprockets are provided on these columns, a drive sprocket is provided that is rotated by a manual steering member, and a drive sprocket is provided between the eccentric sprocket and the drive sprocket. It is made by extending chain means.

In the present invention, it is preferable to add a chain tensioning means for maintaining the chain means at a predetermined tension even if the distance from the eccentric sprocket to the drive sprocket changes during steering.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The drawings show a preferred embodiment of the invention, in which a work trolley 10 comprises a wheeled base 11 and a vertical mast 12.
A workbench 13 is mounted on the mast so as to be movable in the vertical direction. A suitable power mechanism is provided to raise and lower the workbench 13 relative to the base 11.

Base 11 with right front wheel RFW and left front wheel LFW,
A right rear wheel RRW and a left rear wheel LRW are provided. The rear wheels are mounted rotatably around the horizontal axis and cannot be steered around the vertical axis. The front wheels RFW and LFW are mounted so that they can rotate freely around the horizontal axis, and can be steered around the vertical axis. For example, as shown in FIG. 2, the left front wheel LFW is rotatably attached to a bracket 16.
A bearing 1 is constructed by fixing a vertical support 17 to a bracket 16, aligning its axis C _LFW with the vertical axis C _LFW of the left front wheel, and attaching the support 17 to a base frame 19.
Rotatably journal bearing in 8. Similarly, the right front wheel RFW is rotatably attached to a bracket 21, and its support column 22 is journalled in a bearing 23. By aligning the vertical axis of the strut 22 with the vertical axis of the right front wheel RFW and rotating the strut 22 about the vertical axis, the right front wheel can be steered.

A fluid motor 26 is attached to the wheel brackets 16 and 21.
27 and power-drives the front wheels. Conventional power sources, including fluid pumps, reservoirs, and batteries, are mounted within the midsection 28 of the base 11 as usual.

The steering system of the present invention includes right and left sprockets RWS and LWS fixed to columns 22 and 17, and further includes a drive sprocket DS rotatably attached to column 29, and this column is placed approximately at the center of base frame 19. do. drive sprocket
DS is a sprocket member 31 arranged vertically and coaxially,
32, which are connected to each other so that they move together. Connect the first standard roller chain 33 to the upper sprocket member 31 and the right sprocket.
RWS, and the second standard roller chain 34 is hung on the lower sprocket member 32 and the left sprocket LWS.

It is better to use chains and sprockets, but wire ropes, toothed belts,
Other non-extensible means and pulleys may also be used.

A shaft 36 is fixed to the sprocket DS and extends upward into a vertical sleeve 37, which is rotatably mounted on the workbench 13. axis 36
and sleeve 37 have a non-circular cross-section, which allows work platform 13 and sleeve 37 to be moved in a direction perpendicular to axis 36 while maintaining a driving connection between the two.

A handle 38 is fixed to the upper end of the sleeve 37,
This allows the operator to rotate the sleeve 37, shaft 36, and drive sprocket DS to steer the work cart 10.

As shown in Figures 2 and 3, the left sprocket LWS has its center C _LWS aligned with the vertical axis of the left front wheel.
C Mount eccentrically on the support post 17 so that it is eccentric from _{the LFW} to the drive sprocket DS. Similarly, the right sprocket RWS is mounted eccentrically to the strut 22 so that its center C _RWS is eccentric toward the drive sprocket from the vertical axis C _RFW of the right front wheel.

A first chain tensioning means 40 is provided to tighten the right sprocket while keeping the chain 33 appropriately tensioned.
The center of the RWS can be moved toward or away from the axis of the drive sprocket DS. The chain tensioning means 40 is a rigid arm 41
is rotatably mounted on the support column 42 and extends toward the chain 33. Arm 4
1 is pivotally connected to the link 44 of the chain 33 at 43. Similarly, a second chain tensioning means 45 is provided for the chain 34, and its rigid arm 46 is rotatably attached to a column 47, and is pivotally connected at 48 to a link 49 of the chain 34.

FIG. 4 shows the wheel position when the operator turns the handle 38 counterclockwise by 60 degrees to the left as much as possible. Since it is desirable for the work truck 10 to turn around the left rear wheel LRW, the steering system steers the front two wheels so that they are both perpendicular to the through line to the respective left rear wheel. The left front wheel is therefore steered through 90° about its vertical axis. Also, if the work trolley 10 is of a particular size, the front right wheel will be steered 56 degrees to the left about its vertical axis.

As shown in FIG. 5, when the handle 38 is rotated counterclockwise, the drive sprocket is rotated 60 degrees counterclockwise, and the chain 33 is driven in the direction of the arrow. The tensile force of the chain 33 rotates the right sprocket RWS around its center, that is, around the vertical axis C _RFW of the right front wheel, in the counter-hour direction through the part 33b having the link 44, thereby driving the center of the sprocket C _RWS . You can move away from Sprocket DS. Such movement of the sprocket causes the right front wheel to be steered to the left by 56 degrees.

At the same time, the 60° counterclockwise rotation of the drive sprocket DS exerts a tensile force on the chain 34 (on the chain section 34a opposite the section 34b with the link 49), causing the left sprocket LWS to move around its axis of rotation C _LFW . Rotate it so that the center C _LWS of the left sprocket is also moved away from the drive sprocket DS. This movement causes the left front wheel to be steered 90 degrees to the left.

Figures 6 and 7 show the state when the steering wheel 38 is rotated from the neutral position (position where both front wheels are not steered) up to 60 degrees in the direction of the hour hand, and at this time the vehicle is rotated around the right rear wheel. Maximum right turn. The resulting 60 DEG rotation of drive sprocket DC pulls chain section 33a against the right sprocket, causing it to rotate 90 DEG about its axis of rotation C _RFW .
At the same time, drive sprocket DS is connected to chain part 3.
4b to rotate the left sprocket LWS by 56° around its axis C _LFW .

FIGS. 8 to 11 show the operating principle of an eccentric sprocket steering system configured to obtain a desired left and right front wheel steering angle difference depending on the direction of rotation of the drive sprocket. Each of these four drawings is
Left sprocket LWS or right sprocket RWS
and the position of the chain portion 33a or 34a, where the solid line indicates the neutral (non-steering) position, the dotted line indicates the hour hand rotation by 90 degrees (left turn), and the one-dot chain line indicates the hour hand rotation by 90 degrees (left rotation). (right turn). In each of these figures, the ratio of the circumference of the sprocket LWS or RWS to the eccentricity of the sprocket (distance between the center of the sprocket and the axis of rotation) was 20:1.

FIG. 8 shows a steering system in which a line passing through the center C _LWS of the left sprocket and the axis of rotation C _LFW coincides with a line passing through the axis of rotation C _LFW and the center of rotation C _DS of the drive sprocket DS. For simplicity, the left sprocket LWS of the chain part 34a is set to neutral (N).
position, parallel to the line between sprocket centers in either the 90° left (L) position or the 90° right (R) position.
Further, it is assumed that an arbitrary point A on the chain portion 34a is at the position AN when the sprocket LWS is at the neutral position. Points TN, TL, and TR are respectively neutral, 90° left,
The contact of chain portion 34a to the sprocket is shown in the 90° right position.

When the drive sprocket DS is rotated counterclockwise, the chain portion 34a is pulled toward the drive sprocket, causing the sprocket LWS to align with its axis of rotation.
C Rotate the hour hand counterclockwise around _LFW . When the sprocket is rotated 90 degrees, the sprocket center C _LWS moves from point N to point L. Similarly, the contact point of chain portion 34a moves from point TN to point TL.
A 90° rotation of the sprocket will extend the chain by πd/4 (d is the diameter of the sprocket), and this amount of extension is equal to 5 of the sprocket eccentricity e.
equals twice. However, as the contact moves from TN to TL and away from the drive sprocket, point A on chain section 34a moves linearly toward the drive sprocket (from AN to AL) and its amount is πd/4.
is less than the increase in the distance of contact TL from the drive sprocket. In this example, the distance increase (TL-TN) due to the 90° rotation is equal to the sprocket eccentricity e. Therefore, if the linear movement of the chain section 34a toward the drive sprocket is equal to (πd/4-e), a 90° counterclockwise rotation of the sprocket LWS (90° leftward steering of the left front wheel) will occur. If the ratio of sprocket circumference to eccentricity is 20:1, the linear movement of chain portion 34a due to a 90° counterclockwise rotation is equal to 4e. The amount of rotation of the drive sprocket DS required to achieve such linear movement of the chain portion 34a naturally depends on the diameter of the drive sprocket. The sprocket is pulled in the direction of the hour hand (to the right) due to tension from the chain portion 34b (not shown in this figure).
When rotated, chain portion 34a wraps around the sprocket and point A on the chain is moved away from the drive sprocket. The sprocket LWS is
A 90° hourly rotation winds the chain by a length of πd/4, where d is the diameter of the sprocket LWS. At the same time, the contact moves from TN to TR,
It is moved away from the drive sprocket by an amount of eccentricity e. Therefore, when the left sprocket LWS rotates in the direction of the hour hand,
The amount of linear movement of the chain portion 34a (from AN to AL) is (πd/4+e). In this example, this amount of movement is equal to 6e.

What is important here is the drive sprocket that produces a specific amount of rotation in the direction of the hour hand (for example, 90°).
The amount of rotation of the DS in the direction of the hour hand is greater than the amount of rotation of the drive sprocket in the direction of the counter-hour hand to produce the same amount of rotation of the sprocket in the direction of the counter-hour hand. 8th
In the configuration shown in the figure, the drive sprocket DS, which causes the left sprocket LWS to rotate 90 degrees in the hour hand direction (rightward direction) or counterclockwise direction (leftward direction), has a ratio of the amount of rotation in the hour hand direction to the amount of rotation in the counterclockwise direction of 6e:4e. or
Equal to 1.5:1. Similarly, the drive sprocket DS
When rotating the left sprocket LWS by a predetermined amount in both directions, the amount of rotation of the left sprocket LWS in the counter-hour direction (leftward direction) is greater than the amount of rotation in the hour hand direction (rightward direction).

The amount of eccentricity of the sprocket greatly affects the ratio of the sprocket's clockwise rotation to its counterclockwise rotation when the drive sprocket is rotated by a predetermined amount. For example, the 8th
In the figure, if the eccentricity of the sprocket LWS is half of the above value, the amount of chain movement (πd/4-e) when rotating 90° to the left is 9e, and the amount of chain movement (πd/4+e) when rotating 90° to the right is 1.
Becomes 1e. Therefore, the ratio of the amount of rotation of the drive sprocket in the counter-hour direction to the amount of rotation in the hour hand direction to rotate the left sprocket by 90 degrees to the right or left is 11e:
Reduced to 9e or 1.22:1.

FIG. 9 shows a system in which the right sprocket RWS driven by the drive sprocket DS and the chain are mirror images of those in FIG. 8. By the same analysis as above, the drive sprocket DS
and the right sprocket RWS is in the counter-hour direction (to the left)
When the right sprocket rotates 90 degrees, point A on the chain portion 33a moves from AN to
from the drive sprocket DS to (πd/
4+e), where d and e are the diameter and eccentricity of the right sprocket, respectively, which are similar to the left sprocket in mirror-symmetric positions. Similarly, when the right sprocket rotates 90 degrees in the direction of the hour hand (rightward), point A moves from AN to AR and approaches the drive sprocket by (πd/4-e). 9th
In the case of the sprocket RWS shown in the figure, the drive sprocket is used to rotate the sprocket RWS 90 degrees in the direction of the hour hand (to the right) or in the direction of the counter-hour hand (to the left).
The ratio of the rotation amount of the hour hand to the rotation amount of the counterclockwise direction of the DS is the reciprocal of that for the left sprocket LWS.
That is, (πd/4-e): (πd/4+e) or 1:
It becomes 1.5.

Thus, in the steering system using the mirror-symmetric sprockets shown in FIGS. 8 and 9, the drive sprocket DS is rotated counterclockwise by an amount that pulls the chain portion 34a by a distance (πd/4-e). And the left sprocket LWS is
Rotated 90 degrees to the left. At the same time, the chain part 33b
will also move by the same amount (πd/4-e), and if you have the right sprocket, you will rotate it to the left by a smaller angle. Conversely, when the drive sprocket is rotated by the same amount from the neutral position, the chain portions 33a and 34b move by (πd/4-e), causing the right sprocket to move 90 degrees to the right and the left sprocket to the right by a lesser amount. Rotate each.

FIG. 10 shows a configuration similar to FIG. 8, except that the line passing through C _LFW and C _LFW is at a -45° angle to the line passing through C _LFW and _CDS at the neutral position of the left sprocket. In this case, when the left sprocket LWS is rotated 90 degrees counterclockwise (to the left), the contact TN moves away from the drive sprocket by e√2, and TL
leading to. Therefore, point A on the chain is from AN
Move to AL by (πd/4-e√2). When the left sprocket LWS rotates 90° to the right, the contacts TN and
TR is located equidistant from the drive sprocket and chain portion 34a moves by (πd/4).
The ratio of the rotation of the drive sprocket DS in the direction of the hour hand to the rotation in the direction of the counter-hour hand in order to rotate the left sprocket LWS by 90 degrees to the right or left is πd.
= 20e, (πd/4): (πd/4−e√
2), that is, 1.394:1.

FIG. 11 shows a configuration in which the angle between the line C _LFW -C _LWF and the line C _LFW -C _DS is +30°. As mentioned above, when the sprocket LWS is rotated 90 degrees to the left, the amount of linear movement of the chain portion 34a is πd/4,
Less than the distance increase from the drive sprocket when the contact moves from TN to TL. Similarly, when the sprocket LWS is rotated 90 degrees clockwise, the linear movement amount of the chain portion 34a is πd/4, the contact point TL,
It is equal to the sum of the distance increase from the drive sprocket due to TN. In the case of FIG. 11, the ratio of the rotation of the drive sprocket DS in the counter-hour direction to the rotation of the hour hand in order to rotate the left sprocket LWS by 90 degrees to the right or left is about 1.37:1.

If the angles formed by the straight lines C _LFW - C _LWS and C _LFW - C _DS are made different, the amount of chain movement and the rotation ratio of the drive sprocket will be different. However, if the center C _LWS of the sprocket LWS is brought closer to the center C _DS of the drive sprocket than the center of rotation C _LFW in its neutral position, the counterclockwise rotation of the drive sprocket DS in order to rotate the left sprocket LWS 90 degrees to the right or left will be possible. The ratio of rotation in the direction of the hour hand to the rotation in the hour hand direction is 1 or more.
This ratio is maximum in the case of FIG. 8.
Its center in the neutral position of the sprocket LWS
When C _LWS is set farther from the center of the drive sprocket C _DS than the center of rotation C _LFW , the ratio of the rotation of the drive sprocket in the direction of the hour hand to the rotation of the drive sprocket in the counter-hour direction to rotate the sprocket by 90 degrees to the right or left becomes less than 1. The latter configuration is unsuitable for use in the steering system of the present invention, and the reason is that, contrary to the requirements, the left wheel steering amount when turning left is the right wheel turning amount (the opposite when turning right).
This is because there will be less.

In the case of a steering system that turns the vehicle around the rear wheels, the steering ratio between the front wheels is determined by the distance between the four wheels. For example, in the vehicles of FIGS. 1 to 7, the above ratio is 90°:56° or 1.61:1. The diameter of the sprocket is determined as required. At the neutral position of the left sprocket, the lines C _LFW −C _LWS and C _LFW −
The angle formed by C _DS and the amount of eccentricity of the sprocket are:
It is determined that when the drive sprocket is rotated by the same angle from the neutral position toward the hour hand or counterclockwise, the left sprocket will be rotated 56 degrees to the right and 90 degrees to the left. The amount of rotation of the drive sprocket to obtain maximum steering is determined by the relationship between the drive sprocket and the sprocket diameter. One half of the steering system determines the other half, since both halves are mirror images of each other.

In the manufacture of steering systems, it is necessary to provide suitable chain tensioning means 40 for each eccentric sprocket LWS, RWS. As is clear from the foregoing, when the drive sprocket DS is rotated in the direction of the hour hand, the left sprocket LWS is rotated by the tension of the chain portion 34b. If the chain section 34b is elastically biased into a tensioned state, for example the state shown in FIG. You can keep it tense without rotating it to the right.

In systems such as those shown in FIGS. 1-7, where the distance between the sprocket and the drive sprocket increases equally during rotation in both directions from a neutral point, the strut 4
7 and the rigid arm 46 pivotally connected to the chain link 49 provides a reliable, non-compressible means of maintaining tension in the chain as the sprocket and drive sprocket center distances change. Pivot point 4 in Figures 3, 5 and 7
The three positions of 8 define a circle. The center of this circle is located at the post 47 and the radius of this circle determines the length of the arm 46.

As is clear from the foregoing, the present invention has the advantage of keeping the steering force constant. The outer wheel steering force decreases as the inner wheel steering force increases.

Moreover, the above effects can be achieved with an extremely simple configuration in which the sprockets RWS and LWS eccentrically fixed to the wheel steering struts 17 and 22 are directly driven by the drive sprocket DS via the chain means 33 and 34. In addition, this simple configuration does not have any parts where the strength becomes weak even when a large steering force is input.
It is also advantageous in terms of durability.

[Brief explanation of drawings]

FIG. 1 is a side view of a work trolley equipped with the steering system of the present invention, and FIG. 2 is a front view thereof.
Figure 3 is a 3-3 sectional view of Figure 1, Figures 4 and 6.
The figure is a schematic diagram showing the wheel steering situation of the work trolley at maximum left turning and maximum right turning, respectively. Figures 5 and 7 are diagrams showing the steering system at maximum left turning and maximum right turning, respectively. The sectional view corresponding to FIG. 3 and FIGS. 8 to 11 are diagrams of the operating principle of the steering system of the present invention. 10...Work trolley, 11...Base with wheels, 1
2... Vertical mast, 18... Workbench, RFW...
Right front wheel, LFW...Left front wheel, RRW...Right rear wheel,
LRW...Left rear wheel, 16...Wheel bracket, 1
7... Vertical support, 18... Bearing, 19... Base frame, 21... Wheel bracket, 22... Support, 23... Bearing, 26, 27... Fluid motor,
29...Strut, DS...Drive sprocket, 31,
32...Sprocket member, RWS...Right sprocket, LWS...Left sprocket, 33, 34
... Chain, 36 ... Shaft, 37 ... Vertical sleeve, 38 ... Handle, 40, 45 ... Chain tensioning means, 41, 46 ... Rigid arm, 42, 4
7... Support, 43, 48... Pivot point, 49... Chain link.

Claims (1)

[Scope of Claims] 1. A vehicle comprising a substantially horizontal frame, first and second wheels provided at one end thereof, and third and fourth wheels provided at the other end, the first and second wheels being arranged individually. A steering system for a vehicle capable of steering around a vertical axis, comprising: first and second struts attached to the frame so as to be rotatable around its own axis; means for enabling said second wheel to be steered in response to rotation of said second strut about its vertical axis; and means for enabling said second wheel to be steered in response to rotation of said second strut about its vertical axis; and a neutral position. a manual steering member movable in both directions from the sprocket; a first sprocket secured to the first strut for rotation therewith, the first sprocket having a center offset from the axis of the first strut; and a first sprocket secured to the second strut for rotation therewith; a second sprocket whose center is offset from the axis of the second strut; a drive sprocket coupled to the steering member and rotating from the neutral position in response to movement of the steering member from the neutral position; Sprocket and drive sprocket, and in response to rotating the drive sprocket in one direction from the neutral position, the first and second
Rotate the sprocket in one direction from the neutral position,
Chain means for rotating the first and second sprockets in the opposite direction from the neutral position in response to rotation of the drive sprocket in the opposite direction from the neutral position. steering system. 2. The chain means is provided with means for keeping the chain taut around both sprockets and the drive sprocket during rotation in both directions.
Steering system for vehicles described in section. 3. In the neutral position of the drive sprocket, the center of the first sprocket is closer to the axis of the drive sprocket than the axis of the first strut, and the center of the second sprocket is closer to the axis of the drive sprocket than the axis of the second strut. A vehicle steering system according to claim 1.