Gear device for internal combustion engine

Abstract

To provide a gear device for an internal combustion engine that can suppress vibration.SOLUTION: A gear device for an internal combustion engine includes: a first gear fitted to a crankshaft; and a second gear fitted to a balancer shaft and engaging the first gear. The first gear includes a first damper, the second gear includes a second damper, and the first damper has a resonant frequency that is different from the resonant frequency of the second damper.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a gear device for an internal combustion engine.

Background Art

[0002] In order to suppress vibrations generated in an internal combustion engine, a balancer device may be provided. A gear is provided on the crankshaft of the internal combustion engine, and a gear is provided on the balancer shaft of the balancer device. By meshing these gears, the balancer shaft rotates in synchronization with the crankshaft. A technique for suppressing vibrations has been developed by providing a rubber damper on the gear of the balancer device (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, vibrations may not be sufficiently suppressed. Therefore, an object of the present invention is to provide a gear device for an internal combustion engine capable of suppressing vibrations.

Means for Solving the Problems

[0005] The above object is achieved by a gear device for an internal combustion engine, comprising a first gear attached to a crankshaft, and a second gear attached to a balancer shaft and meshing with the first gear. A balancer mass is attached to the balancer shaft, The first gear two plate portions and has a first damper, and the second gear two plate portions and has a second damper. the two plate portions of the first gear, the two plate portions of the second gear, the first damper and the second damper have an annular shape, the first damper is provided between the two plate portions of the first gear, the second damper is provided between the two plate portions of the second gear, and the first damper is thinner than the second damper, so that The resonance frequency of the first damper is the resonance frequency of the second damper higher and can be achieved by the gear device of the internal combustion engine.

Effects of the Invention

[0006] It is possible to provide a gear device for an internal combustion engine capable of suppressing vibration.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0008] FIG. 1 is a perspective view illustrating a gear device 100 according to an embodiment. The gear device 100 has two gears. The gear 10 (first gear) is attached to the tip of the crankshaft 30 of the internal combustion engine. The gear 20 (second gear) and the balancer mass 34 are attached to the tip of the balancer shaft 32. The crankshaft 30 and the balancer shaft 32 are spaced apart from each other and parallel to each other.

[0009] FIG. 2(a) is a front view illustrating the gear 10. The gear 10 has a plate portion 12, a plate portion 14, and a damper 16 (first damper). The plate portion 12, the plate portion 14, and the damper 16 each have an annular shape. A plurality of teeth 12a are provided on the outer peripheral surface of the plate portion 12. The plurality of teeth 12a are arranged along the direction of the outer periphery of the plate portion 12. The plate portion 14 is located at the center in the radial direction of the gear 10. The damper 16 is the portion hatched in FIG. 2(a). The damper 16 is provided between the plate portion 12 and the plate portion 14. That is, the damper 16 is attached to the outer peripheral surface of the plate portion 14, and the plate portion 12 is attached to the outer peripheral surface of the damper 16.

[0010] Figure 2(b) is a front view illustrating the gear 20. The gear 20 has a plate portion 22, a plate portion 24, and a damper 26 (second damper). The plate portion 22, the plate portion 24, and the damper 26 each have an annular shape. A plurality of teeth 22a are provided on the outer peripheral surface of the plate portion 22. The plurality of teeth 22a are arranged along the direction of the outer periphery of the plate portion 22. The plate portion 24 is located at the center in the radial direction of the gear 20. The damper 26 is the portion shaded in Figure 2(b). The damper 26 is provided between the plate portion 22 and the plate portion 24. That is, the damper 26 is attached to the outer peripheral surface of the plate portion 24, and the plate portion 22 is attached to the outer peripheral surface of the damper 26.

[0011] The plate portions 12 and 14 of the gear 10 and the plate portions 22 and 24 of the gear 20 are formed of, for example, metal or resin. The plate portion may be formed of a material containing iron, such as ductile cast iron (FCD: Ferrum Casting Ductile). The dampers 16 and 26 are formed of rubber.

[0012] When the crankshaft 30 rotates, the gear 10 also rotates together with the crankshaft 30. The plurality of teeth 12a of the gear 10 mesh with the plurality of teeth 22a of the gear 20. For this reason, power is transmitted from the gear 10 to the gear 20. The gear 20 rotates in synchronization with the gear 10. The balance shaft 32 rotates together with the gear 20.

[0013] The resonance frequency of the damper 16 is different from the resonance frequency of the damper 26. The thickness T1 of the damper 16 shown in Figure 2(a) is smaller than the thickness T2 of the damper 26 shown in Figure 2(b). Since the damper 16 is thinner than the damper 26, the rigidity of the damper 16 is higher than the rigidity of the damper 26. The strain rate of the damper 16 is lower than the strain rate of the damper 26. The resonance frequency of the damper 16 is higher than the resonance frequency of the damper 26.

[0014] By providing dampers on both of the two gears, vibration is suppressed. However, when the resonance frequencies of the two dampers are equal, the vibrations of the two dampers increase at the resonance frequency. It is difficult to suppress the vibration at the resonance frequency.

[0015] According to this embodiment, the gear 10 has a damper 16, and the gear 20 has a damper 26. The resonance frequency of the damper 16 is different from the resonance frequency of the damper 26. Therefore, it is suppressed that both the damper 16 and the damper 26 vibrate at the same frequency. As a result, vibration can be suppressed.

[0016] By suppressing vibration, the generation of noise and the load on the gears 10 and 20 can be suppressed. By making the resonance frequencies different between the two dampers, vibration can be suppressed. It is not necessary to increase the size of the damper for vibration suppression.

[0017] The damper 26 is thicker than the damper 16. The rigidity of the damper 16 becomes higher than the rigidity of the damper 26, and the resonance frequency of the damper 16 becomes higher than the resonance frequency of the damper 26. The thickness T2 of the damper 26 may be, for example, 1.2 times or more, 1.5 times or more, 2 times or more of the thickness T1 of the damper 16.

[0018] In order to make the resonance frequencies different, it is only necessary that the thickness T1 of the damper 16 is different from the thickness T2 of the damper 26. For example, the damper 16 may be thicker than the damper 26. However, by making the damper 16 thicker, the rigidity of the damper 16 becomes lower than the rigidity of the damper 26, and the strain rate of the damper 16 becomes higher than the strain rate of the damper 26. A load is applied to the damper 16 from a balancer mass 34 or the like. When a load is applied to the damper 16 with low rigidity, the damper 16 may be damaged. In order to make the resonance frequencies different and increase the rigidity of the damper 16, the damper 16 is made thinner than the damper 26. The rigidity of the damper 16 can be increased and breakage can be suppressed.

[0019] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of reference numerals

[0020] 10, 20 Gears Plates 12, 14, 22, 24 Teeth 12a, 22a Dampers 16, 26 Crankshaft 30 Balancer shaft 32 Balancer mass 34 Gear device 100

Claims

**Claim 1** a first gear attached to a crankshaft; a second gear attached to a balance shaft and meshing with the first gear; a balance mass is attached to the balance shaft; the first gear has two plate portions and a first damper; the second gear has two plate portions and a second damper; the two plate portions of the first gear, the two plate portions of the second gear, the first damper, and the second damper have an annular shape; the first damper is provided between the two plate portions of the first gear; the second damper is provided between the two plate portions of the second gear; a gear device for an internal combustion engine, wherein the first damper is thinner than the second damper, so that a resonance frequency of the first damper is higher than a resonance frequency of the second damper.

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