JPH0335660Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention [Field of Industrial Application] The present invention relates to a steering gear device that forms the core of a four-wheel steering device installed in a vehicle that is equipped with wheels on the front, rear, left, and right sides of the vehicle body.

[Conventional technology]

A four-wheel steering device is known in which when a steering wheel is turned, the front wheels and rear wheels are turned in opposite phases and can turn in a small radius.

However, even with a small steering angle operation of the steering wheel, the rear wheels are turned in the opposite direction to the front wheels. Because the steering system has so-called linear characteristics, the responsiveness of the steering wheel is sensitive when driving straight, making it difficult to maintain straight driving.

Therefore, in order to solve the above-mentioned problems, the present applicant first proposed a four-wheel steering system that can obtain nonlinear steering characteristics (Japanese Patent Application No. 59-268787) (Japanese Patent Application No. 1987-268787).
146679)).

In other words, when operating the steering wheel 1 at a small steering angle,
Rear wheel 3 is hardly turned, or rear wheel 3
The structure is such that the front wheels 2 and 3 are turned in the same phase as the front wheels 2 and at a small angle, and when a large steering angle is operated, the front and rear wheels 2 and 3 are turned in opposite phases.

The steering gear device of the four-wheel steering device proposed above includes a pinion and a sector gear that rotate integrally with the steering wheel, and two sets of gear meshing portions of a planetary gear mechanism for obtaining nonlinear steering characteristics in a small steering angle operation range. It has a crank movement part.

[Problem that the invention attempts to solve]

Since the two pairs of meshing parts and the crank movement part of the steering gear require precise and reliable movement, it is desirable to prevent dirt and muddy water from entering the steering gear.

In view of the above points, it is an object of the present invention to prevent foreign matter from entering the steering gear device, prevent deterioration of the durability of the device, and obtain a steering gear device that is highly reliable over a long period of time.

B. Structure of the invention [Means for solving the problem] In order to achieve the above object, the present invention, as shown in the drawings, has the following features:
Rear wheel 3 is hardly turned, or rear wheel 3
In a four-wheel steering system, the lower end of the central axis 4 of the steering handle 1 pinion 5, sector gear 6 that meshes with pinion 5, sector gear 6
a crank support arm 7 integral with the crankshaft 7, a crankshaft with a journal portion 8A bearing on the arm 7, a planetary gear 9 integrally provided on the crankshaft 8, an immovable sun gear 10 meshing with the planetary gear 9, and the crankshaft 8. Relay rod 1 with the rear wheel steering system connected to the crank pin 8B of
1 is housed in the gear box 12, and the lower end 13A of the shaft 13, which rotates integrally with the sector gear 6 and the crank support arm 7, is housed in the gear box 12.
The base of the pitman arm 14 of the front wheel steering system is fixed to the shaft end 13A of the shaft.

[Effect]

The meshing parts of the pinion 5 and sector gear 6 that rotate together with the steering handle 1, the meshing parts of the planetary gear 9 and sun gear 10 for obtaining nonlinear steering characteristics in the range of small steering angle operations, and the crankshaft 8 and gear box 12 are all included. Because it is contained, there is no dirt or muddy water.

〔Example〕

The vehicle shown in FIG. 1 is a riding type agricultural tractor equipped with the steering gear system of the present invention, and various working machines are connected to the rear end or the front end. Wheels 2 and 2 are provided on each left and right sides of the front and rear parts of the vehicle body frame 15.
and 3.3, the engine 16 mounted on the front part of the vehicle body frame 15 is covered with a bonnet 17,
A steering wheel 1 and a driver's seat 18 are provided behind the engine 16.

Power from the engine 16 is transmitted via a propulsion shaft 19 to a transmission attached to the rear of the vehicle body frame 15.
Further, the power is transmitted from the transmission to the rear wheels 3 and front wheels 2.

Each of the front wheels 2 and 2 is free to change direction around a king pin 20, a knuckle arm 21 extending rearward is fixed to the king pin 20, and one end of a tie rod 22 is connected to the knuckle arm 21 with a universal joint. The other end is similarly connected by a universal joint to the left and right front ends of a pitman arm 14 protruding forward from below the gearbox 12 of the steering gear.

Further, each of the rear wheels 3 and 3 can also freely change direction around a king pin 23, and a knuckle arm 24 extending toward the inside of the vehicle body is fixed to the king pin 23.
One end of a tie rod 25 is connected to the knuckle arm 24 by a universal joint, and the other end of the tie rod 25 is connected by a universal joint to the left and right ends of a bell crank type lever 27 attached to the center of the vehicle body by a support shaft 26.

One end of the bell crank type lever 27 and the crank pin 8B in the gear box 12 of the steering gear are connected by a relay rod 11 arranged obliquely to the longitudinal centerline of the vehicle body.

The gearbox 12 of the steering gear device is formed into upper and lower halves, and the pinion 5 and the sector gear support shaft 13 are connected to a pair of boss portions 28, 29, 3 provided oppositely on the upper and lower surfaces of the gearbox 12.
It is bearing with 0.31. Planetary gear 9
The crankshaft 8 having a shape formed therein is supported so as to vertically pass through a U-shaped bent portion 7A provided at the end of an arm 7 integral with the sector gear 6. Planetary gear 9
The sun gear 10, on which the sun gear 10 rolls, is positioned by fitting its center portion 10A onto the sector gear support shaft 13, and is fixed to the inside of the upper surface of the gear box 12 by bolts 32. A bellows-shaped rubber tube 33 is placed around the relay rod 11 to protect it. A breather 34 is provided on the top surface of the gearbox 12 in order to prevent the air pressure inside the gearbox 12 from fluctuating due to the deformation of the rubber cylinder 33 due to the movement of the relay rod 11, and to suppress the collapse or bulging of the rubber cylinder 33. It is set up. The breather 34 includes a filter 35 that prevents dust from entering.

C. Effects of the invention Since the steering gear device for four-wheel steering of the invention has the above configuration, the pinion 5 and sector gear 6 rotate integrally with the steering handle 1, which is the main mechanism, and the small steering angle operation range. Two sets of gear meshing parts of the planetary gear mechanism 9 and 10 that produce nonlinear steering characteristics and crank movement parts 8B and 11
A, etc. are covered by the gear box 12 and are prevented from getting dirt or muddy water.

Therefore, it prevents deterioration of the durability of those mechanisms,
This has the effect of ensuring reliability of the steering function over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional side view of the front half of a vehicle equipped with the steering gear device for four-wheel steering of the present invention, Fig. 2 is a plan view showing the four-wheel steering mechanism, and Fig. 3 is a longitudinal cross-section of the steering gear device of the present invention. A side view, and FIG. 4 is a cross-sectional plan view thereof. 1... Steering handle, 2... Front wheel, 3... Rear wheel, 4... Center shaft of handle, 5... Pinion,
6...Sector gear, 7...Crank support arm,
8...Crankshaft, 8A...Journal part, 8B
... Crank pin, 9 ... Planetary gear, 10
... Sun gear, 11 ... Relay rod, 12 ... Gear box, 13 ... Sector gear shaft, 14 ...
Pittman arm.

Claims (1)

[Scope of utility model registration request] When operating the steering wheel at a small steering angle, the rear wheels are hardly turned, or the rear wheels are turned in the same phase as the front wheels and at a small angle, and when the steering wheel is operated at a large steering angle, the front and rear wheels are turned in opposite phases. In the four-wheel steering device, a pinion at the lower end of the center shaft of the steering handle, a sector gear meshing with the pinion, a crank support arm integrated with the sector gear, a crankshaft with a journal part bearing on the arm,
A planetary gear integrally provided on the crankshaft, an immovable sun gear that meshes with the planetary gear, and an end of a relay rod connecting the rear wheel steering system connected to the crank pin of the crankshaft are housed in a gear box, A steering gear device for four-wheel steering in which the lower end of a shaft that rotates integrally with a support arm projects outward from the bottom of a gearbox, and the base of a pitman arm of a front wheel steering system is fixed to the shaft end.