Balancer Device

Abstract

To suppress generation of deviation in phase between a driven gear and a balance shaft.SOLUTION: A balancer device for an internal combustion engine includes: a driven gear 13 engaging a crank gear installed to a crankshaft; a friction ring 14 press-fitted and fixed into an inner periphery of the driven gear 13; and a balance shaft 11 inserted into an inner periphery of the friction ring 14. The friction ring 14 has a shape which is asymmetric with respect to a rotation direction and generates different frictional forces depending on a rotation direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] An internal combustion engine is used as a power source for a vehicle. Patent Document 1 discloses a balancer device as the internal combustion engine, the balancer device including a crankshaft, a crank gear drivingly connected to the crankshaft, a first balance shaft, and a first driven gear connected to the first balance shaft via a damping mechanism that allows relative rotation.

[0003] Here, the damping mechanism has a friction damper that generates a frictional force to damp the relative rotation between the first driven gear and the counter gear fixed to the first balance shaft when the first driven gear and the counter gear fixed to the first balance shaft rotate relatively within a predetermined rotational phase range, and a stopper rubber that elastically deforms only when the first driven gear and the first balance shaft rotate relatively beyond the predetermined rotational phase range, and uses the elastic force to counteract the relative rotation.

[0004] With this configuration, even when a rotational force containing a mixture of low-frequency and high-frequency components is input as vibration components, the occurrence of resonance phenomena caused by these vibration components can be suitably suppressed without causing damage to or deterioration of the functionality of the damping mechanism. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-193794 A Summary of the Invention [Problem to be solved by the invention]

[0006] The balancer device disclosed in Patent Document 1 has a problem in that the rotation phase between the first driven gear and the first balance shaft is not determined. This is because the rotation phase is determined by the rotational force from the crank gear, the frictional force of the friction damper, and the rotational sliding resistance of the balance shaft, and the balancer device disclosed in Patent Document 1 does not have a configuration for actively controlling the rotation phase. Therefore, in an engine used as an internal combustion engine, the actual balance rate of the balance shaft decreases, which may lead to worsening of vibration.

[0007] The present invention provides a balancer device that suppresses engine vibrations. [Means for solving the problem]

[0008] The balancer device of the present invention is a balancer device for an internal combustion engine, and comprises a driven gear that meshes with a crank gear provided on a crankshaft, a friction ring that is press-fitted and fixed onto the inner periphery of the driven gear, and a balance shaft that is inserted into the inner periphery of the friction ring, wherein the friction ring has an asymmetric shape with respect to the direction of rotation and generates frictional forces that differ depending on the direction of rotation. This makes it possible to suppress the occurrence of a phase shift between the driven gear and the balance shaft. Effect of the Invention

[0009] This makes it possible to suppress engine vibration. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a perspective view showing a configuration example of a balancer device. [Diagram 2] FIG. [Diagram 3] FIG. 11 is a front view showing another example of a phase state of the friction ring. [Figure 4] 11 is a front view showing a state in which the stopper rubber and the claw are in a first phase state. FIG. [Diagram 5]13 is a front view showing a state in which the stopper rubber and the claw are in a second phase state. FIG. [Figure 6] FIG. 13 is a diagram showing the change in phase when the engine speed is changed with an associated friction ring. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First embodiment Fig. 1 is a diagram showing an example of the configuration of a balancer device 1 for an internal combustion engine. As shown in Fig. 1, the balancer device 1 includes a first balance shaft 11, an annular damper cover 12, a first driven gear 13, a friction ring 14, a stopper rubber 15, a claw 16, a first drive gear 17, a second balance shaft 18, a second driven gear 19, and a balance mass 20. Note that the description will be given assuming that the internal combustion engine is an engine.

[0012] The first balance shaft 11 is a shaft provided so as to extend in a predetermined direction, and has a tip end portion which is press-fitted and fixed into the damper cover 12 .

[0013] In the following description, the extension direction of the first balance shaft 11 is defined as the extension direction of the balancer device 1. Furthermore, the direction perpendicular to the extension direction of the first balance shaft 11 is defined as the radial direction, and the direction around the axis in which the extension direction of the first balance shaft 11 is the axial direction is defined as the circumferential direction or the rotation direction. Moreover, the viewpoint from the front in Fig. 2, Fig. 4, and Fig. 5 described later is defined as the viewpoint from the extension direction side.

[0014] The cup-shaped damper cover 12 has a hole into which the first balance shaft 11 can be press-fitted. Furthermore, a plurality of stopper rubbers 15 are provided inside the cup-shaped damper cover 12. Claws 16 provided on the first driven gear 13, which will be described later, are fitted between the plurality of stopper rubbers 15.

[0015] The first driven gear 13 is an annular gear having a plurality of teeth along the circumferential direction of its outer periphery, and meshes with a crank gear (not shown) of the crankshaft. An annular friction ring 14 is press-fitted and fixed to the inner periphery of the first driven gear 13.

[0016] Furthermore, the first driven gear 13 is provided with a plurality of claws 16 protruding in the extension direction. Specifically, the plurality of claws 16 each protrude toward a stopper rubber 15 provided on the damper cover 12.

[0017] Here, the first balance shaft 11 is movable relative to the first driven gear 13, and the range of movement is restricted by the damper cover 12 and the stopper rubber 15. Here, the stopper rubber 15 is continuous in an annular shape when viewed from the front, and is provided with a predetermined interval between each other. As described later, a plurality of claws 16 are arranged between these stopper rubbers 15.

[0018] Fig. 2 is a front view showing an example of the friction ring 14. As shown in Fig. 2, the friction ring 14 is formed by an annular portion 14a formed in an annular shape and a plurality of protrusions 14b protruding inward from the annular portion 14a. The plurality of protrusions 14b are formed continuously in the circumferential direction of the annular portion 14a and have an asymmetric shape in the circumferential direction. Furthermore, as shown in Fig. 2, the rotation direction of the first balance shaft 11 here is counterclockwise.

[0019] Furthermore, of the protrusion 14b of the friction ring 14, the inner vertex portion is designated as vertex 31, the tapered portion extending from the vertex 31 in a clockwise direction to the annular portion 14a is designated as a first tapered portion 32, and the tapered portion extending from the vertex 31 in a counterclockwise direction to the annular portion 14a is designated as a second tapered portion 33.

[0020] 2, of one protrusion 14b of the friction ring 14, the first tapered portion 32 is shorter in the circumferential direction than the second tapered portion 33. In addition, the first balance shaft 11 is inserted into the inner periphery of the friction ring 14.

[0021] Here, Figure 3 is a cross-sectional view showing the state in which the first balance shaft 11 is inserted into the inner circumference of the first driven gear 13 via a friction ring 14, and the first driven gear 13 is connected to the damper cover 12 via a claw 16.

[0022] 1, the first drive gear 17 is fixed to the first balance shaft 11. As shown in FIG. 1, in terms of the positional relationship in the extension direction of the damper cover 12, the first driven gear 13, and the first drive gear 17, the damper cover 12 is provided on the leading end side, the first drive gear 17 is provided on the rear end side, and the first driven gear 13 is disposed between the damper cover 12 and the first drive gear 17.

[0023] The second balance shaft 18 is a shaft disposed in parallel to the first balance shaft 11. In other words, the extension direction of the second balance shaft 18 is parallel to the extension direction of the first balance shaft 11. A second driven gear 19 is fixed to the second balance shaft 18.

[0024] A second driven gear 19 fixed to the second balance shaft 18 meshes with a first driving gear 17 fixed to the first balance shaft 11. Therefore, when the first balance shaft 11 rotates, force is transmitted to the second driven gear 19 via the first driving gear 17, and a rotational force is applied to the second balance shaft 18.

[0025] The balance mass 20 is connected to each of the first balance shaft 11 and the second balance shaft 18, and balances the inertial force of the engine.

[0026] Next, a description will be given of the operation of the balancer device 1 and the effects of each part. First, the occurrence of a change in phase between the first driven gear 13 and the first balance shaft 11 and the influence of the change in phase will be described.

[0027] The first balance shaft 11 is movable in the rotational direction relative to the first driven gear 13. At this time, the movable range of the first balance shaft 11 is restricted by a stopper rubber 15 and a claw 16 provided on the damper cover 12.

[0028] 4 shows a state where the first driven gear 13 and the first balance shaft 11 are in a predetermined phase in the rotational direction. Here, the first driven gear 13 is driven by the crank gear and rotates in the direction of the arrow shown in FIG.

[0029] At this time, as shown in Figure 4, the state in which the phase of the claw 16 provided on the first driven gear 13 and the damper cover 12 fixed to the first balance shaft 11 is a predetermined phase, that is, the state in which the counterclockwise end of the claw 16 is close to the clockwise end of each of the multiple stopper rubbers 15, is the first phase state.

[0030] The balance mass 20 is connected to the first balance shaft 11 and the second balance shaft 18 so as to achieve optimal balance in the first phase state.

[0031] On the other hand, the driving force that the first driven gear 13 receives from the crankshaft changes in a complex manner from moment to moment. Therefore, the first balance shaft 11 receives torque from the first driven gear 13 via the friction ring 14, but the torque is not necessarily equal for different rotation directions. Therefore, the first phase state shown in Fig. 4 is not stable, and depending on the operating conditions, the phase state may be as shown in Fig. 5, or may be in an intermediate state between the phase states shown in Fig. 4 and Fig. 5.

[0032] The phase state shown in Fig. 5 is defined as a second phase state. Specifically, the second phase state is a state in which the clockwise end of the claw 16 is close to the counterclockwise end of each of the multiple stopper rubbers 15.

[0033] 6(a) and 6(b) show an example of actual measurement of the phase state between the first driven gear 13 and the first balance shaft 11, i.e., the phase state between the claw 16 provided on the first driven gear 13 and the damper cover 12 fixed to the first balance shaft 11, using a related friction ring. Note that FIG. 6(a) shows the state in which the engine speed is changed over time, and FIG. 6(b) shows the phase state at that time. The related friction ring used here is a friction ring similar to the friction ring 14, in which the first tapered portion 32 and the second tapered portion 33 are formed symmetrically.

[0034] More specifically, as shown in Figures 6(a) and 6(b), when the engine speed is about 3000 rpm, the phase state transitions from the first phase state shown in Figure 4 to the second phase state shown in Figure 5. Then, the second phase state is maintained until the engine speed reaches about 1500 rpm.

[0035] At this time, since the balance mass 20 is based on the first phase state shown in Figure 4, when the phase of the first driven gear 13 and the first balance shaft 11 transitions from the first phase state to the second phase state, the actual balance rate decreases and engine vibration increases.

[0036] On the other hand, as described above, in the balancer device 1, the first tapered portion 32 of the friction ring 14 can be made to have a shape that is shorter in the circumferential direction than the second tapered portion 33 and is formed asymmetrically.

[0037] That is, since the projections 14b of the friction ring 14 are asymmetric in shape with respect to the rotation direction of the first balance shaft 11, the torque transmitted by the first balance shaft 11 due to friction is also asymmetric. Therefore, the friction ring 14 can generate different frictional forces depending on the rotation direction of the shaft disposed therein.

[0038] This makes it difficult for a phase shift to occur between the first driven gear 13 and the first balance shaft 11. In other words, the phase between the first driven gear 13 and the first balance shaft 11 is more likely to be maintained in the first phase state shown in Fig. 4, and it is possible to suppress the occurrence of a transition from the first phase state to the second phase state shown in Fig. 5. Therefore, the number of phase changes is reduced, and the occurrence of engine vibration can be suppressed.

[0039] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. In other words, the above description has been omitted or simplified as appropriate for the purpose of clarity, and a person skilled in the art can easily modify, add, or convert each element of the embodiment within the scope of the present invention. [Explanation of symbols]

[0040] 1. Balancer device 11 First balance shaft 12 Damper cover 13 1st driven gear 14 Friction ring 14a Circular section 14b Protrusion 15 Stopper rubber 16 Claws 17 First drive gear 18 Second balance shaft 19 Second driven gear 20 Balance Mass 31 Vertex 32 First tapered section 33 Second taper section

Claims

[Claim 1] A balancer device for an internal combustion engine, comprising: a driven gear having a plurality of claws protruding in an extension direction and meshing with a crank gear provided on the crankshaft; a friction ring press-fitted and fixed to an inner periphery of the driven gear; a balance shaft inserted into the inner periphery of the friction ring; a damper cover into which the tip end of the balance shaft is press-fitted and which has a plurality of stopper rubbers therein, The friction ring is The shape is asymmetric with respect to the direction of rotation, generating different frictional forces depending on the direction of rotation. The plurality of claws include The claw and the damper cover are held in a predetermined phase state with the claw being housed between the plurality of stopper rubbers and the counterclockwise end of the claw being close to the clockwise end of the stopper rubber. Balancer device.

Images