JPS581416Y2 - mechanical power steering - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to mechanical power steering in wheel steered vehicles, particularly wheel tractors.

Most conventional power steering systems are hydraulic, but hydraulic systems require components such as hydraulic pumps and specially constructed valve devices that are expensive and require advanced manufacturing technology.

Also, like the hydraulic type, mechanical power steering has a complicated structure, is expensive, and has the disadvantage that it will lock up unless a special operation is performed when the engine is stopped.

The present invention was developed in view of the above circumstances, and aims to provide a mechanical power steering system that is compact, easy to operate like a hydraulic system, and has a simple structure that can be manufactured at low cost. .

An embodiment of the present invention will be described below with reference to the drawings.

The tractor 1 has a body 5 supported by front wheels 2 and rear wheels 3.
The engine 6 is located in front of the fuselage 5, and the steering wheel γ is located in the middle of the fuselage.

The engine 6 connects the rear wheels 3 to 1 via the transmission 8.
While driving, the power shaft 12 is rotated at a reduced speed via the rotating shaft 10 and the reduction gear transmission 11.

The steering wheel 7 is connected to the front wheels 2 by a drag link rod 14 or the like via a power steering device 13 according to the present invention.
to steer.

The power steering device 13, as shown in FIG.
The steering shaft 16 is housed in a housing 15, and a steering shaft 16 projects from a part of the housing 15, and a steering shaft 7 is fixed to the projecting end thereof.

The axial movement of the steering shaft 16 is restricted by the housing 15, and the other end has a spline 17 formed on its outer periphery and a screw hole 18 formed in its center.

Further, a steering worm 20 is supported by the housing 15 so as to be rotatable only.
A spline 2L22 is formed at both ends of the spline 2L22, and a through hole 23 is bored in the center of the spline 2L22, and a groove 25 is formed in the upper spline 211.
(see figure).

Joint flanges 26 and 27 are fixed to the splines 17 of the steering shaft 16 and the splines 21 of the steering worm 20, respectively.
An elastic coupling 30, as shown in detail in FIG. 4, is clamped and fixed between 6° and 27 by bolts 28.

The steering worm 20 meshes with a sector gear 31, and the gear 31 fixes a pitman arm 33 via a pitman shaft 32.

The pitman arm 33 is linked to the front wheel 2 via the drag link rod 14.

A cylindrical body 37 having truncated cone-shaped friction clutches 35 and 36 disposed facing each other at both ends thereof is slidably supported on the spline 22 of the steering worm 20, respectively.

A control rod 38 passes through the through hole 23 of the steering worm 20, and is held in the worm 20 so as to be able to slide freely by engaging a pin 39 with the groove 25 of the spline 21. One end is screwed into the screw hole 18 of the steering shaft 16, and the other end is a flange 40 that is rotatably held in an annular groove 41 of a cylindrical body 37 formed by a retaining ring 40.

Two bevel gears 43 and 45, which are rotatably supported by the housing 15 and the collar 39, are disposed between both friction clutches 35 and 36 of the cylindrical body 37, and the bevel gears 43 and 45 are connected to the power shaft 12. The bevel gear 46 is rotatably supported by the bevel gear 46.

The side end portion of the bevel gear 46 is serrated, and the side end portion of the bevel gear 46 is serrated.
A collar 47 having a similar serrated side end slidably supported by a spring 48 is pressed and engaged with the collar 47;
A one-way clutch 50 is configured.

Next, the effects of this embodiment will be explained.

Now, when the steering shaft 16 is rotated in the direction of the arrow hole in Fig. 2 by the steering wheel 7, the joint flange 1
7. Elastic coupling 30 and joint flange 27
The steering worm 20 is attempted to be rotated in the same direction via the .

However, the worm 20 is connected to the sector gear 31. It does not rotate easily because it receives resistance from the ground pressure of the front wheels through the pitman arm 33, track link rod 14, etc.

The elastic coupling 30 therefore deforms to compress its rubber, causing the steering wheel shaft 16 to rotate relative to the steering worm 20.

As a result, the pin 39 of the worm 20 is engaged with the groove 25 formed in the spline 21 of the worm 20, and the control rod 38, which is prevented from rotating relative to the worm 20, is engaged with the screw hole 18 of the steering shaft 16 with a right-hand screw. Because there is
Control rod 38 slides in the direction of arrow B.

Since the control rod 38 is configured to slide integrally with the cylindrical body 37 through the flange 42 and the annular groove 41, the cylindrical body 37 also slides in the same direction, and the friction clutch 36 on the lower side thereof is moved downward. It engages with the bevel gear 43 on the side.

The power shaft 12 is constantly rotating in the direction of arrow C due to the rotation of the engine 6, and this rotation is also transmitted to the bevel gear 43 as rotation in the direction of arrow A via the collar 47, the -manku clutch 50, and the bevel gear 46. Therefore, it is transmitted to the steering worm 20 via the spline 22.

Therefore, the steering worm 20 obtains most of its power from the power shaft 12, rotates the sector gear 31 in the direction of the arrow, and rotates the pitman shaft 32 and the pitman arm 3.
3 and a drag link rod 14 to steer the front wheels 2.

Next, when the steering wheel 7 is rotated in the opposite direction to that described above,
Contrary to the above, the elastic coupling 30 is deformed so as to be stretched, and the steering shaft 16 rotates relative to the steering worm 20.

The control rod 38 slides in the direction opposite to the arrow B by being screwed into the screw hole 18 and engages the upper friction clutch 35 of the cylindrical body 37 with the upper bevel gear 45 .

As a result, rotation in the direction opposite to the arrow A is applied to the steering worm 20, and the sector gear 31 is rotated in the direction opposite to the arrow A, thereby operating the front wheels 2 in the opposite direction to that described above.

In addition, a straight-line restoring force, that is, a force to return to the center position, is applied to the sector gear 31 from the front wheel 2 via the pitman arm 33, etc., but when the steering wheel 7 is finished operating in a predetermined direction, the steering wheel 7 When the applied force is removed, the elastic strain of the elastic coupling 30 disappears, so the steering worm 20 is rotated in the opposite direction by the linear restoring force acting on the sector gear 31, and the steering worm 20 is automatically rotated in the same way as a general steering wheel. returns to its central position.

Furthermore, even if the front wheel 2 collides with a protruding object on the ground or the like and a force acting to strongly rotate the steering worm 20 via the pitman arm 33, sector gear 31, etc.
When the driver holds the steering wheel 7 so as not to turn it, the elastic coupling 301 is strained, and this causes the power shaft 12 to apply a force that cancels out the rotation, so the steering wheel 7 can be turned with a light force. You can maintain the vehicle's direction by simply holding it.

Furthermore, even if the power shaft 12 is stopped due to the engine 6 being stopped, when the bevel gear 46 attempts to rotate due to the operation of the steering wheel 7, the collar 47 is engaged with the spring 4 due to sawtooth engagement.
8, and the one-way clutch 50 is disengaged, so the bevel gear 46 rotates freely with respect to the power shaft 12, and although there is no power steering effect by the power shaft 46, the steering operation is controlled. can do.

FIG. 5 shows a partially modified embodiment.

Note that the same parts are given the same reference numerals and the description thereof will be omitted.

The steering shaft 66 is slidably and rotatably supported by the housing 15, and a cylindrical body 51 having a screw hole 68 on the inner periphery is fixed to the lower end of the steering shaft 66.

The steering worm 70 is rotatably supported by the housing 15, and its upper end is a threaded portion 52 that engages with the screw hole 68, and its lower end is a spline 72 having a groove 75 in a portion thereof. Furthermore, a through hole 73 is formed in the center.

A control rod 88 made of a torsion bar is provided in the through hole 73.
is held, and its upper end is fixed to the steering shaft 66 by a pin 53, and its lower end is slidably engaged with the groove 75 of the spline 72 by a pin 89.

Therefore, in this embodiment, when the steering shaft 66 is rotated in the direction of the arrow A, the steering worm 70 is rotated via the pin 53, the control rod 88, the pin 89, and the groove 75, but the front wheel 2 causes the sector gear to rotate. Since resistance is applied to the worm 70 via the steering wheel 31, the control rod 88 consisting of a torsion bar is twisted, and the steering shaft 66 rotates relative to the steering worm 70.

Then, the steering shaft 66 is in a threaded relationship with the threaded portion 52 through the screw hole 68, and the steering worm 70 is fixed in the sliding direction.
is lifted up while rotating, and the pin 53 and control rod 8
8, the cylindrical body 37 is also slid in the same direction via the flange 42 and the annular groove 41.

As a result, the friction clutch 36 of the cylindrical body 31 is connected to the bevel gear 43.
As described above, the rotation of the power shaft 12 in the direction of arrow C causes the collar 47, the one-way clutch 50 and the bevel gears 46, 4 to
It is conveyed through 3.

Therefore, the sector gear 31 rotates in the direction indicated by the arrow, and the front wheels 2 are steered via the pitman shaft 32, pitman arm 33, and drag link rod 14.

The operation by rotating the steering shaft 66 in the direction opposite to the arrow A is also similar, so a description thereof will be omitted.

As explained above, the present invention allows the driver to
When turned in any direction, most of the force can be turned by the power mechanically transmitted from the engine 6,
Further, since the power is automatically cut off when the steering wheel 7 is stopped turning, the steering operation force is significantly reduced, and even women and girls can easily drive a large vehicle.

In addition, unlike hydraulic power steering, it does not require special equipment, nor does it have a complicated structure like other mechanical power steering, so it can be manufactured easily.

Furthermore, accidents such as the steering wheel being accidentally turned off can be prevented by simply holding the steering wheel γ lightly without impairing the ability of the vehicle to straighten the vehicle.

Furthermore, even if the engine 6 stops, the vehicle can be steered without having to specifically release the power steering mechanism, so there is no chance that the engine will stop while the vehicle is running and the vehicle will suddenly become inoperable and cause a major accident.

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view showing a tractor to which the present invention is applied, Fig. 2 is a side sectional view showing a mechanical power steering according to the invention, and Fig. 3 is a control rod and its component parts. FIG. 4 is a perspective view showing the engaged state of the steering worm, FIG. 4 is a plan view showing the elastic coupling, and FIG. 5 is a view similar to FIG. 2 showing another actual case. 2... (steering) wheel, 6... engine, 7... steering, 12... power shaft, 16... steering shaft, 1B, 52, 6B... screw means (screw hole, threaded part), 20... Steering drive body (worm), 30.88... Elastic body (elastic coupling, torsion bar), 35.36... Clutch, 43, 45
゜46...Rotating body (bevel gear), 50...One-way clutch.

Claims (1)

[Scope of utility model registration request] (1) A steering shaft that is linked to the steering, a steering drive body that is linked to the steering wheel, an elastic body that connects the steering shaft and the steering drive body so that they can be relatively angularly displaced; screw means sliding in the axial direction of the steering drive body;
A power shaft driven by an engine, a rotating body driven to rotate in opposite directions by the power shaft, and the rotation of either of the rotating bodies is transmitted to the steering drive body by sliding of the screw means. Mechanical power steering consisting of a clutch≧(2) between the power shaft and the rotating body,
The mechanical power steering system according to claim 1, wherein a one-way clutch is interposed to transmit power only when power is transmitted from the power shaft to the rotating body.