Variable track rod spacing automobile steering gear

Abstract

The utility model relates to a steering transmission mechanism of automobile, including cam, left and right cam push rod, cam axle, cam frame, its characterized in that cam axle (5) is fixed on the steering gear housing, axial and automobile steering axle parallel, especially to the steering trapezoidal transmission mechanism improved steering transmission mechanism. The mechanism is composed of cam, left and right cam push rod, cam axle, cam frame. The mechanism makes automobile steering each wheel all make pure rolling through the realization real-time variable cross tie rod spacing, effectively reduces the additional resistance of automobile travel, lightens the sideslip of vehicle, further improves automobile travel stability and driving comfort, and lightens tire wear.

Description

Technical Field

[0001] This utility model relates to automotive steering transmission mechanisms, and in particular to an improved steering transmission mechanism for a trapezoidal steering transmission mechanism. Background Technology

[0002] Modern automobiles all use a trapezoidal steering transmission mechanism. The ideal relationship for the two steering wheels to achieve pure rolling is (Equation 1): ctgα = ctgβ + B / L In the formula: β - deflection angle of the inner steering wheel; α - deflection angle of the outer steering wheel; B - distance between the intersection points of the two kingpin axes and the ground; L - wheelbase.

[0003] Currently, the steering trapezoidal design of automobiles can only be effectively configured within a certain range of wheel deflection angles to approximate the ideal relationship described above. See page 294 of *Automotive Structure*, Volume 2, edited by Shi Wenku and Yao Weimin, Department of Automotive Engineering, Jilin University, People's Transportation Press, 6th edition, June 2013. This error caused by the steering trapezoidal design accelerates wear on the steering wheels, increases steering resistance, and can also cause vehicle sideslip, affecting driving stability and comfort. Summary of the Invention

[0004] The purpose of this utility model is to address the shortcomings of the existing technology by improving the trapezoidal transmission mechanism for automobile steering. By using a cam mechanism, the distance between the tie rods can be changed in real time, so that the deflection angles of the inner and outer steering wheels conform to the ideal steering angle relationship (Equation 1), and all wheels can roll purely when the car is steering.

[0005] The above-mentioned objective of this utility model is achieved by the following technical solution.

[0006] The automotive steering transmission mechanism consists of a cam, left and right cam pushrods, a camshaft, and a cam carrier. The camshaft is fixed to the steering gear housing, with its axis parallel to the front axle of the vehicle. The cam carrier is fixedly connected to the steering rack (steering rocker arm) and moves left and right with the steering rack. The cam is rotatably connected to the cam carrier, is axially fixed, and moves left and right with the cam carrier while also being rotatable. The cam is helically connected to the camshaft, rotating helically around the camshaft, with the rotation direction opposite when the cam moves left and right. The left and right cam pushrods are slidably connected to the cam carrier, with their axes parallel to the camshaft, and can slide left and right on the cam carrier. The inner sides of the left and right cam pushrods mate with the left and right cam grooves of the cam, respectively, and the outer sides are hinged to the left and right tie rods, respectively.

[0007] The cam has two cam grooves, left and right, with opposite shapes in both the left-right and up-down directions. The cam groove curve is composed of curved segments and straight segments, and the dividing lines between the curved and straight segments of the left and right cam grooves coincide. When the cam rotates forward, it causes the left cam pusher to move to the left relative to the cam, while the right cam pusher remains stationary relative to the cam axis. When the cam rotates in the reverse direction, it causes the right cam pusher to move to the right relative to the cam, while the left cam pusher remains stationary relative to the cam axis.

[0008] The functional expression for the cam groove curve is (Equation 2): ΔS=Mcosθ+√(T 2 -(e-Msinθ) 2 )-S-Mcos(θ+arccot(cotα-B / L))-√(T 2 -(e-Msin(θ+(arccot(cotα-K / L)))) 2 ) The expression for the deflection angle α of the outer steering wheel is (Equation 3): α=θ-actsin((-b+√(b 2 -4ac)) / (2a)) In the formula: ΔS - tie rod spacing increment; S - steering rack (steering rocker arm) displacement; α - outer steering wheel deflection angle; θ - steering trapezoidal base angle; M - steering arm length; T - tie rod length; e - distance between the cam pushrod and the front axle; B - distance between the intersection points of the two kingpin axes and the ground; L - wheelbase; a = 4e 2 M 2 +4M 2 (S+d) 2 b = -4eM((s+d) 2 +M 2 +e 2 -T 2 c = (s + d) 2 +M 2 +e 2 -T 2 ) 2 -4M 2 (s+d) 2 ; d=Mcosθ+√(T 2 -(e-Msinθ) 2 ).

[0009] When the car is moving straight ahead, the camshaft, left and right cam pushrods, camshaft, and cam carrier are all in their initial positions. The inner sides of the left and right cam pushrods are at the innermost side of the cam slots, and the distance between the outer sides of the left and right cam pushrods, i.e., the distance between the inner sides of the left and right tie rods, is the shortest. The steering deflection angles α and β of the two steering wheels are both zero.

[0010] When the car turns left, the camshaft carrier moves to the left along with the steering rack (steering rocker arm), causing the cam to move to the left and rotate around the camshaft in the positive direction. The cam causes the left and right cam pushers to move to the left and slide along the cam grooves, with the displacement of the left cam pusher being greater than that of the right cam pusher. The left and right cam pushers cause the left and right tie rods to move to the left, with the displacement of the left tie rod being greater than that of the right tie rod, and the distance between the inner sides of the left and right tie rods increasing. The left and right tie rods cause the left and right steering wheels to produce corresponding steering deflection angles. At this time, the deflection angle β of the left wheel (i.e., the inner steering wheel) is greater than the deflection angle α of the right wheel (i.e., the outer steering wheel).

[0011] When the car turns right, the camshaft carrier moves to the right along with the steering rack (steering rocker arm), causing the cam to move to the right and rotate in the opposite direction around the camshaft. The cam causes the left and right cam pushers to move to the right and slide along the cam grooves, with the displacement of the right cam pusher being greater than that of the left cam pusher. The left and right cam pushers cause the left and right tie rods to move to the right, with the displacement of the right tie rod being greater than that of the left tie rod, increasing the distance between the inner sides of the left and right tie rods. The left and right tie rods then cause the left and right steering wheels to produce corresponding steering deflection angles. At this time, the deflection angle β of the right wheel (i.e., the inner steering wheel) is greater than the deflection angle α of the left wheel (i.e., the outer steering wheel).

[0012] Theoretical calculations, geometric drawings, and actual measurements all demonstrate that the automotive steering transmission mechanism provided by this invention not only ensures that the inner wheel steering deflection angle β is greater than the outer wheel steering deflection angle α, but also precisely conforms to the ideal steering angle relationship (Equation 1). Therefore, it enables all wheels to rotate around the same instantaneous steering center during steering, with each wheel rolling purely without sideslip. Compared to existing trapezoidal transmission mechanisms, it more effectively reduces additional resistance during vehicle movement, mitigates vehicle sideslip, further improves vehicle stability and driving comfort, and reduces tire wear—this is the most fundamental advantage of this invention. Other advantages include: simple structure, easily determined and measured geometric parameters, convenient installation and use, low cost, and high efficiency. Attached Figure Description

[0013] Appendix Figure 1 This is a diagram showing the installation location of this utility model. Figure 2 This is a schematic diagram of the steering transmission mechanism of this utility model when the car is traveling straight. Figure 3 This is a schematic diagram of the steering transmission mechanism of this utility model when a car is turning left. Figure 4 This is a schematic diagram of the steering transmission mechanism of this utility model when a car is turning right. Figure 5 This is the isometric drawing of this utility model. Detailed Implementation

[0014] The embodiments of this utility model are described in detail below with reference to the accompanying drawings. In the drawings, 1 is the left cam push rod, 2 is the right cam push rod, 3 is the cam, 4 is the cam carrier, 5 is the camshaft, and 6 is the steering rack (steering rocker arm). As shown in the figure, the camshaft 5 is assumed to have a double-threaded left-hand screw, and the screw lead is equal to the maximum stroke of the steering rack (steering rocker arm) 6. Let the displacement be S, and the displacement increment be ΔS. When the car turns left or right, its steering control mechanism and steering gear cause the steering rack (steering rocker arm) 6 to produce a displacement S to the left or right, causing the cam carrier 4 provided by this utility model to move left or right by S, driving the cam 3 to move left or right along the camshaft 5 by S and rotate downward or upward, thereby driving the left cam push rod 1 and the right cam push rod 2 to move left or right, and increasing the axial distance between the left cam push rod 1 and the right cam push rod 2 by ΔS. When turning left, the displacement of left cam push rod 1 is S + ΔS, and the displacement of right cam push rod 2 is S; when turning right, the displacement of right cam push rod 2 is S + ΔS, and the displacement of left cam push rod 1 is S. Left cam push rod 1 and right cam push rod 2 respectively drive the left and right tie rods to move left or right, increasing the distance between the inner sides of the tie rods by ΔS. The tie rods then drive the left and right steering wheels to generate corresponding steering deflection angles α or β. Regardless of whether turning left or right, the deflection angle β of the inner steering wheel is greater than the deflection angle α of the outer steering wheel, and conforms to the ideal steering angle relationship (Equation 1).

Claims

1. A variable tie rod spacing automotive steering transmission mechanism, comprising a cam, left and right cam pushrods, a camshaft, and a cam carrier, characterized in that... The camshaft (5) is fixed on the steering gear housing and its axis is parallel to the steering shaft of the car. The cam frame (4) is fixedly connected to the steering rack (6) and moves left and right with the steering rack (6). The cam (3) is rotatably connected to the cam frame (4) and is fixed in the axis. It moves left and right with the cam frame (4) and can rotate. The cam (3) is helically connected to the camshaft (5) and rotates helically around the camshaft (5). The rotation direction of the cam (3) when it moves left and right is opposite. The left cam push rod (1) and the right cam push rod (2) are slidably connected to the cam frame (4) and their axes are parallel to the camshaft (5). They can slide left and right on the cam frame (4). The inner sides of the left cam push rod (1) and the right cam push rod (2) are respectively engaged with the left and right cam grooves of the cam (3), and the outer sides are respectively connected to the left and right tie rods.

2. The automotive steering transmission mechanism according to claim 1, characterized in that... The cam (3) has two cam grooves, left and right. The shapes of the two grooves are opposite in the left-right and up-down directions. The cam groove curve is composed of curved segments and straight segments. The dividing line between the curved segments and straight segments of the left and right cam grooves coincides. When the cam (3) rotates in the forward direction, it drives the left cam push rod (1) to move to the left relative to the cam (3) axis, while the right cam push rod (2) remains stationary relative to the cam (3) axis. When the cam (3) rotates in the reverse direction, it drives the right cam push rod (2) to move to the right relative to the cam (3) axis, while the left cam push rod (1) remains stationary relative to the cam (3) axis.

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