Design of a rear bushing for a flat spring suspension system of a light commercial vehicle with resistance to wear and tear

Abstract

The claimed part is "a steering wheel cover for a mid-size sedan made of EPDM with heat, sound, water and dust filtration capabilities", which has three main parts:\nThe first part, which is cylindrical, sits on the steering box.\nThe second part is a spatial form that serves as a cover for the steering wheel.\nThe third part is a bean-shaped ring that covers the firewall sheet.\nThe edge shape and tolerances in the first and third parts were selected by pressing to sit completely on the firewall and steering box and make them watertight. Due to the hardness of the compound and the reinforcing ribs, the part is firmly fixed in place without the need for any connection or intermediary and does not allow any exchange of heat, sound, water and dust. Also, the intended compound is resistant to engine heat and can maintain its performance during the operation of the vehicle. This part is installed in the automotive industry on the SP100 platform in the mid-range sedan category.

Description

Description of the invention Title of the invention Design of the rear bushing of the flat spring suspension system of a light commercial vehicle with the ability to resist wear and tear Technical background of the relevant invention The present invention relates to the field of mechanical engineering and automotive parts. Technical problem and stating the objectives of the invention Commercial vehicles are used to transport heavy loads, so their rear axle usually uses a rigid suspension system with leaf springs. The leaf spring is connected to the vehicle body by an earring-shaped mechanism in order to provide proper movement in the suspension system. Since the leaf spring is connected to the wheels of the rear axle, it is subjected to continuous vibrations along the path of movement, which can be transmitted to the vehicle body and greatly reduce the comfort of the vehicle's journey. Therefore, it is necessary to install 8 rubber bushings to filter vibrations in the earring location on the right and left sides of the vehicle (Figure 1). When commercial vehicles are loaded, large forces are generated on the rear axle of the vehicle, which are divided between the front and rear sides of the leaf spring, so large loads are applied to the bushings behind the leaf spring. Since these bushings are mounted to the earrings by a bolt, the contact surface between them is small, which causes large stresses on them. Also, the unevenness of the road causes rotational movement on the earrings and the bushings, as a result of which the rubber part of the bushings is easily torn and cannot have a proper durability or life. The rupture of the bushings causes the earring to hit the leaf spring and the rear bushing, creating unusual noises that reduce the comfort of the vehicle's journey. Also, as the rubber bushing of the rear leaf spring wears, the leaf spring's travel range increases, which greatly reduces the vehicle's handling. The claimed invention is designed to solve the above-mentioned problems. This part consists of two components: rubber and metal, with the metal part serving as a protective cover for the rubber part, which prevents direct wear of the rubber part with the flat spring and the rear casing connected to the body, and also leads to a uniform distribution of force on the rubber. The material and dimensions of the rubber part are designed in such a way that it is pressed into the metal part and allows the earring to move, while at the same time preventing it from hitting the flat spring and the rear casing. A description of the state of the prior art and the history of developments related to the claimed invention. According to searches conducted on the website of the Patent Office in the country and the Google patent and Patent scope sites, no similar examples with the claimed product capabilities have been found for the platform available in the Iranian market. Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention The claimed part is "Design of the rear bushing of the flat spring of a light commercial vehicle suspension system to prevent wear and tear" (Figure 2 - Drawing 8) and has two main parts: The first part (Figure 3) is an external edged metal bushing whose edge shape is placed on the flat spring or rear casing connected to the body and prevents direct wear of the rubber bushing with them and also causes uniform distribution of the preload resulting from the assembly of the earrings on the rubber part. During the operation of the part, this edge causes the rubber part to maintain its shape and prevents possible impacts of the earrings on the flat spring and rear casing, which improves the comfort of the vehicle's journey. In addition, the cylindrical part of the external edged metal bushing is placed between the rubber bushing and the flat spring or rear casing connected to the body and reduces wear between them, which leads to the durability of the part. A tube made of TSE-1C-1E material according to the B535105 standard with a thickness of 1.5 mm was used for the edged metal bushing. According to the standard, carbon is less than or equal to 10%, manganese is less than or equal to 50%, silicon is less than or equal to 10%, sulfur and phosphate are less than or equal to 5%. Also, the yield stress and ultimate stress are at least 350 Mpa and 420 Mpa, respectively, and its hardness is at least HV 126 (Figure 4).The second part (Figure 5) is a rubber bushing whose edge is placed between the outer metal bushing and the earring and prevents these two metal surfaces from colliding with each other during the operation of the vehicle. Also, the dimensions and tolerances of its cylindrical part are designed in such a way that it is assembled inside the first part by pressing without the need for any intermediate or adhesive, and during the operation of the vehicle, the forces resulting from the mass of the load being carried are distributed on this part. The material of the claimed part has been selected in such a way that it provides the required durability and hardness while being low in thickness, so the NR compound with a hardness of 65 to 75 Shore A has been considered for this purpose. The tensile strength of this compound is at least 14 MPa and its elongation at break is at least 200%. Also, this component must be able to maintain its performance well in high temperature conditions, so changes in tensile strength of up to 30% and changes in elongation of up to 50% have been considered for the compound, and an ozone test has also been defined for it to ensure that the compound maintains its elastic properties due to thermal stresses and does not develop surface cracks.The tear strength of the compound is defined as at least 10 KN / m and its length must increase by at least 200% before tearing. Also, due to compressive forces, the compound is allowed to permanently deform by a maximum of 50% (Figure 6). The radial static stiffness of the claimed part under a preload of N100 Newtons must be within the range of 2153 ± 15% N / mm, and its dynamic stiffness at a frequency of 1 Hz and a displacement range of ± 1 mm should be less than 500 N / mm, and at a frequency of 15 Hz and a displacement of ± 0.5 mm, should be less than 650 N / mm. Also, the claimed part under a preload of Kgf331 and an oscillating force of Kgf219 in the radial direction and a torsional load with a variation range of ± 20 ° should be able to go through at least 200 thousand cycles without any rupture or crack (Figure 7). Explanation of shapes, maps and diagrams Figure 1: Rigid suspension system assembly with leaf spring on the rear axle 1-Spring bed 2-axle axle 3-Earrings 4-Rear casing attached to the body 5- Assembly location of the rear rubber bush of the flat spring 6-Wheel installation location Figure 2: Rear rubber bushing of the flat spring 1-External edged metal bushing part 2-Rubber bushing part Figure 3: Externally edged metal bushing 1-Metal bushing edge 2-Cylindrical part of metal bushing Figure 4: Test results of the properties of the edged metal bushing Figure No. 5: Rubber bushing 1-Edge 2-Cylindrical part Figure 6: Compound properties test results Figure 7: Results of radial static hardness, dynamic hardness and durability tests on the claimed part Figure 8: Two-dimensional product map A clear and precise statement of the advantages of the claimed invention over prior inventions. Improving travel comfort, vehicle handling and consumer satisfaction  Increasing the durability of the piece Reducing vehicle maintenance costs Save time by eliminating the need for frequent part replacement Description of at least one implementation method for implementing the invention The claimed part is a "design of a rear leaf spring bushing for a light commercial vehicle suspension system with the ability to resist wear and tear" that is installed on the left and right sides of the rear axle of the vehicle. Two leaf spring rear bushings are assembled on both sides of the rear casing connected to the body and two bushings are assembled in the leaf spring housing. Two earrings are placed between the leaf spring and the rear casing and connect the leaf spring to the vehicle body by means of two screws passing through the rubber bushings. During the operation of the vehicle, the rocker mechanism of the suspension system allows the wheel to move up and down. Explicit mention of the industrial application of the invention The part is "Design of a rear bushing for a flat spring suspension system of a light commercial vehicle with the ability to resist wear and tear" which is used in the automotive industry and the manufacture of automotive parts and on a light commercial vehicle in the Iranian market.

Claims

Claim What is claimed: 1- The claimed part is the rear bushing of the flat spring of the suspension system of a light commercial vehicle, which consists of two parts: a rubber bushing and an outer edged metal bushing that is capable of resisting wear and tear. 2- According to claim 1, the first part of the external edged metal bushing is a rimmed cylinder whose rim shape is placed on a flat spring or rear sheath connected to the body, causing the rim of the rubber bushing to maintain its shape and the cylindrical part to prevent the rubber bushing from directly wearing on them, and also causing uniform distribution of force on the rubber part.

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