Balance shaft for range extender two-cylinder engine

Abstract

The utility model relates to a balance shaft for a range extender two-cylinder engine. The balance shaft comprises a balance shaft body, a first ball bearing, a second ball bearing and a balance shaft gear, the balance shaft body is integrally formed by a first cylindrical section, a balance shaft, a deviation weight, a second cylindrical section and a third cylindrical section, the first ball bearing is arranged on the first cylindrical section in a sleeving mode, and the second ball bearing is arranged on the second cylindrical section in a sleeving mode. The first cylindrical section is sleeved with the first ball bearing, the second cylindrical section is sleeved with the second ball bearing, the third cylindrical section is sleeved with the balance shaft gear, the first cylindrical section is further provided with a check ring installation groove, and an elastic check ring is installed in the check ring installation groove. The first cylindrical section, the balance shaft, the deviation heavy block, the second cylindrical section and the third cylindrical section are integrally formed, so that the balance shaft and the deviation heavy block do not need to be assembled, the assembling procedure, a positioning tool for assembling and part of connecting bolts are omitted, the assembling efficiency can be obviously improved, and the production cost is saved.

Description

Technical Field

[0001] This utility model relates to an engine balance shaft, and more particularly to a balance shaft for a range extender two-cylinder engine. Background Technology

[0002] Range extenders typically use two-cylinder engines. In the engine field, balance shafts are commonly used to balance the first and second order reciprocating inertial forces of the engine's piston connecting rod mechanism. The assembly of balance shafts on engines falls into two categories: one is a box-type structure, such as... Figure 1 The balance shaft shown consists of two balance shafts assembled in one housing, bolted to the bottom of the cylinder block, and driven by a chain or gear; another type is as follows... Figure 2 As shown, the balance shaft is a modular structure. The balance weight, balance shaft drive gear and other parts are assembled onto the balance shaft by bolts. The balance shaft is then assembled onto the side of the cylinder block. The balance shaft and the cylinder block are connected by needle roller bearings, ball bearings and other types of bearings.

[0003] Figure 1 The balance shaft shown is a dual-shaft structure, used to balance the second-order reciprocating inertial force of a four-cylinder engine, but it is not suitable for two-cylinder or three-cylinder engines. Figure 2 The balance shaft structure shown can balance the first-order reciprocating inertial force of an engine and is suitable for two-cylinder and three-cylinder engines. However, as can be seen from the figure, this type of structure has the following problems: First, the balance shaft has many assembly parts, making assembly complex, difficult, and inefficient; second, there are strict relative positional requirements between the balance weight and the balance shaft, requiring special tooling or alignment marks during assembly, resulting in high assembly requirements and high costs; third, bolts are needed to tighten the balance weight and balance shaft drive gear, requiring the design of an additional high-strength bolt, leading to long assembly cycles and high costs. These problems result in high production costs and low production efficiency for this type of balance shaft. Summary of the Invention

[0004] This invention provides a balance shaft for a two-cylinder engine used in a range extender, solving the problem of low assembly efficiency and high production costs caused by excessive assembly structures in existing balance shafts.

[0005] The above-mentioned technical problems of this utility model are mainly solved by the following technical solution: a balance shaft for a two-cylinder engine of a range extender, comprising: a balance shaft body, a first ball bearing, a second ball bearing, and a balance shaft gear. The balance shaft body is integrally formed from a first cylindrical section, a balance shaft, a biasing weight, a second cylindrical section, and a third cylindrical section. The balance shaft is located between the first cylindrical section and the second cylindrical section. Several biasing weights are provided and spaced apart on the balance shaft. The first ball bearing is sleeved on the first cylindrical section, the second ball bearing is sleeved on the second cylindrical section, and the balance shaft gear is sleeved on the third cylindrical section. The first cylindrical section is also provided with a retaining ring mounting groove, and an elastic retaining ring is installed in the retaining ring mounting groove, the elastic retaining ring restricting the first ball bearing to its inner side.

[0006] This invention integrates the first cylindrical section, balance shaft, offset weight, second cylindrical section, and third cylindrical section into one piece through casting or forging processes. Therefore, no assembly is required between the balance shaft and the offset weight, saving assembly steps, positioning fixtures for assembly, and some connecting bolts. This can significantly improve assembly efficiency and save production costs.

[0007] The specific assembly process is as follows: First, the first ball bearing is press-fitted into the cylinder block mounting hole, with an interference fit between the first ball bearing and the mounting hole; then, the second ball bearing is press-fitted onto the second cylindrical section of the balance shaft body, and then the balance shaft gear is press-fitted onto the third cylindrical section to obtain the balance shaft assembly; the assembled balance shaft assembly is then assembled into the cylinder block, and the elastic retaining ring is then assembled into the retaining ring mounting groove to limit the axial movement of the balance shaft body.

[0008] Both the second ball bearing and the balance shaft gear are interference-fitted with the balance shaft. Assembly can be achieved by cooling the balance shaft body with liquid nitrogen or by heating the second ball bearing and the balance shaft gear. The inner ring of the first ball bearing has a transition fit with the first cylindrical section, and the outer ring of the second ball bearing has a transition fit with the mounting hole on the cylinder block, to facilitate assembly. During assembly, the positional relationship between the balance shaft gear and the balance shaft body is precisely controlled using tooling.

[0009] Therefore, this utility model has the following characteristics compared with the prior art: 1. The first cylindrical section, the balance shaft, the bias weight, the second cylindrical section and the third cylindrical section are integrally formed, so there is no need to assemble the balance shaft and the bias weight, saving assembly process, assembly positioning tooling and some connecting bolts, which can significantly improve assembly efficiency and save production costs. Attached Figure Description

[0010] Appendix Figure 1 This is a schematic diagram of a box-type balance shaft.

[0011] Appendix Figure 2This is a schematic diagram of a combined balance shaft structure;

[0012] Appendix Figure 3 This is a disassembly diagram of the present invention;

[0013] Appendix Figure 4 This is a schematic diagram of the structure of this utility model;

[0014] Appendix Figure 5 This is a structural schematic diagram of the balance shaft body;

[0015] Appendix Figure 6 This is a schematic diagram of another structure of the balance shaft body.

[0016] In the diagram: 1. Balance shaft assembly; 2. Balance shaft mounting bolts; 3. Cylinder block; 4. Mounting bolts; 5. Counterweight; 6. Balance shaft drive gear; 7. Retaining ring; 8. Bearing; 9. Balance shaft; 10. Bearing outer ring; 11. Needle roller bearing. Detailed Implementation

[0017] The technical solution of this utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0018] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0019] Example 1: See Figure 3 and Figure 4 A balance shaft for a two-cylinder engine in a range extender includes: a balance shaft body 10, a first ball bearing 20, a second ball bearing 30, and a balance shaft gear 40. The balance shaft body is integrally formed from a first cylindrical section 50, a balance shaft 60, four offset weights 70, a second cylindrical section 80, and a third cylindrical section 90. The balance shaft is located between the first and second cylindrical sections. The offset weights are spaced apart on the balance shaft. The first ball bearing is sleeved on the first cylindrical section, the second ball bearing is sleeved on the second cylindrical section, and the balance shaft gear is sleeved on the third cylindrical section. The first cylindrical section is also provided with a retaining ring mounting groove 51, and an elastic retaining ring 52 is installed in the retaining ring mounting groove, which restricts the first ball bearing to its inner side.

[0020] In this embodiment, the first cylindrical section, balance shaft, offset weight, second cylindrical section, and third cylindrical section are integrally formed by casting or forging. Therefore, there is no need for assembly between the balance shaft and the offset weight, which saves assembly steps, positioning fixtures for assembly, and some connecting bolts, and can significantly improve assembly efficiency and save production costs.

[0021] The specific assembly process is as follows: First, the first ball bearing is press-fitted into the cylinder block mounting hole, with an interference fit between the first ball bearing and the mounting hole; then, the second ball bearing is press-fitted onto the second cylindrical section of the balance shaft body, and then the balance shaft gear is press-fitted onto the third cylindrical section to obtain the balance shaft assembly; the assembled balance shaft assembly is then assembled into the cylinder block, and the elastic retaining ring is then assembled into the retaining ring mounting groove to limit the axial movement of the balance shaft body.

[0022] Both the second ball bearing and the balance shaft gear are interference-fitted with the balance shaft. Assembly can be achieved by cooling the balance shaft body with liquid nitrogen or by heating the second ball bearing and the balance shaft gear. The inner ring of the first ball bearing has a transition fit with the first cylindrical section, and the outer ring of the second ball bearing has a transition fit with the mounting hole on the cylinder block, to facilitate assembly. During assembly, the positional relationship between the balance shaft gear and the balance shaft body is precisely controlled using tooling.

[0023] The balance shaft is eccentrically set, and the eccentric direction is consistent with the eccentric direction of the weight. The balance shaft is provided with reinforcing ribs 61 distributed along the length direction on the side opposite to the eccentricity.

[0024] See Figure 5 and Figure 6 The first cylindrical section has a first positioning hole 53 coaxially located on its end face, and the third cylindrical section has a second positioning hole 91 coaxially located on its end face, and a third positioning hole 92 eccentrically located. The first and second positioning holes are used for positioning during the machining stage, and the third positioning hole is used for positioning when installing the balance shaft gear.

[0025] This invention can be modified in many ways, as will be apparent to those skilled in the art, and such modifications are not considered to depart from the scope of this invention. All such modifications that are obvious to those skilled in the art are included within the scope of these claims.

Claims

1. A balance shaft for a two-cylinder engine with a range extender, characterized in that, include: The balance shaft body comprises a first ball bearing, a second ball bearing, and a balance shaft gear. The balance shaft body is integrally formed from a first cylindrical section, a balance shaft, offset weights, a second cylindrical section, and a third cylindrical section. The balance shaft is located between the first and second cylindrical sections. Several offset weights are provided and spaced apart on the balance shaft. The first ball bearing is sleeved on the first cylindrical section, the second ball bearing is sleeved on the second cylindrical section, and the balance shaft gear is sleeved on the third cylindrical section. The first cylindrical section is also provided with a retaining ring mounting groove, in which an elastic retaining ring is installed, restricting the first ball bearing to its inner side.

2. The balance shaft for a two-cylinder engine with a range extender according to claim 1, characterized in that: The balance shaft is eccentrically set, and the eccentric direction is consistent with the eccentric direction of the biased weight. The balance shaft has reinforcing ribs distributed along its length on the side opposite to the eccentricity.

3. The balance shaft for a two-cylinder engine with a range extender according to claim 1, characterized in that: The first ball bearing and the first cylindrical section have a transition fit, the second ball bearing and the second cylindrical section have an interference fit, and the balance shaft gear and the third cylindrical section have an interference fit.

4. The balance shaft for a two-cylinder engine with a range extender according to claim 1, characterized in that: The first cylindrical segment has a first positioning hole coaxially arranged on its end face, the third cylindrical segment has a second positioning hole coaxially arranged on its end face, and a third positioning hole eccentrically arranged.

5. The balance shaft for a two-cylinder engine with a range extender according to claim 2, characterized in that: The number of biased weights is 4.

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