JP3712540B2 - Power transmission device capable of absorbing shock - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power transmission device that can be used for a propulsion shaft, a steering column, and the like of an automobile and can absorb impact energy in the axial direction.
[0002]
[Prior art]
In this type of power transmission device, for example, as disclosed in JP-A-9-123774, a shaft member of the power transmission device and a tubular member fitted to the shaft member can be relatively moved in the axial direction by a spline joint. In addition, the shaft member and the tubular member are connected to each other by a snap ring mounted in a circumferential groove formed at a corresponding position between the shaft member and the tubular member.
[0003]
The power transmission device transmits a rotational driving force between the shaft member and the tubular member. On the other hand, when a force of a predetermined value or more acts in the axial direction, the shaft member is rubbed against the tubular member by a spline joint. While moving in the axial direction while receiving resistance, the snap ring is removed from the inside of the circumferential groove to absorb the impact energy in the axial direction.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional example, the snap ring is intended to absorb the impact energy in the axial direction exclusively by removing the snap ring from the circumferential groove rather than the frictional resistance of the spline joint, and the stable friction of the spline joint. There is nothing special about getting resistance.
[0005]
That is, according to the research by the inventors, when the tip of the outer spline formed on the shaft member is in the middle of the axial direction of the inner spline formed on the tubular member as in the conventional example, the friction resistance of the spline joint varies. It will occur.
[0006]
For this reason, in the conventional example, there is a possibility that a stable impact energy absorption effect may not be obtained due to variations in the frictional resistance of the spline joint.
[0007]
The present invention has been devised in view of the above-described conventional situation, and an object of the present invention is to provide a power transmission device capable of absorbing an impact and capable of absorbing an impact energy by a stable frictional resistance of a spline joint.
[0008]
[Means for Solving the Problems]
In view of this, the invention according to claim 1 is characterized in that the shaft member and the tubular member fitted to the shaft member are connected by a spline joint so as to be relatively movable in the axial direction and not to be relatively rotatable in the rotational direction. In a possible power transmission device,
The outer spline formed on the shaft member is press-fitted to the inner spline formed on the tubular member,
The outer spline formed on the shaft member is formed longer in the axial direction than the inner spline formed on the tubular member,
In the initial state in which the shaft member and the tubular member are connected, both ends of the outer spline formed on the shaft member protrude in the axial direction from the end of the inner spline formed on the tubular member.
[0009]
According to a second aspect of the present invention, in the configuration of the first aspect of the invention, one or both of the outer spline formed on the shaft member and the inner spline formed on the tubular member is a helical spline. It is.
[0010]
According to a third aspect of the present invention, in the configuration of the second aspect of the present invention, the outer spline formed on the shaft member is a helical spline.
[0011]
In such a configuration, the tooth shape and the number of teeth of the outer spline and the inner spline are arbitrary. Moreover, it is arbitrarily possible to attach a snap ring or a severable pin (shearing pin) to the connection between the shaft member and the tubular member so as to obtain a large impact absorption energy.
[0012]
According to such a configuration, the outer spline formed on the shaft member is press-fitted into the inner spline formed on the tubular member, and the shaft member and the tubular member are relatively movable in the axial direction and are relatively rotated in the rotational direction. It is linked immovably. At this time, the outer spline of the shaft member is formed longer in the axial direction than the inner spline of the tubular member, and in the initial state where the shaft member and the tubular member are connected, both ends of the outer spline formed on the shaft member are It press-fits so that it may protrude in the axial direction from the edge part of the inner spline formed in the tubular member. As a result, a power transmission device connected by the spline joint is formed.
[0013]
The power transmission device is responsible for power transmission of rotational torque, and when a force greater than a predetermined value is applied in the axial direction, the shaft member and the tubular member are relatively moved in the axial direction while receiving frictional resistance by the spline joint. By doing so, the impact energy in the axial direction is absorbed.
[0014]
Here, the load by which the outer spline formed on the shaft member is press-fitted into the inner spline formed on the tubular member is, as shown in FIG. 3, the outer spline press-fitted to the inner spline in the axial direction. As a result, the peak value A1 is shown at the time when the tip of the outer spline exits the inner spline, and after that, it decreases slightly and shows a characteristic having a region in which it changes from B1 to C1 substantially flatly. Further, these press-fit load characteristics change as indicated by broken lines when the dimensions of the outer spline and the inner spline vary within an allowable range, and the respective loads become characteristics A2, B2, and C2. Show.
[0015]
Here, the difference in the press-fitting fitting load is that the mutual difference (P1) between the peak values A1 and A2 is relatively large, and the mutual difference (P2) between the loads B1 and B2 and C1 and C2 in a substantially flat region is relatively large. It will be small. That is, when the tip of the outer spline formed on the shaft member is in the axial direction of the inner spline formed on the tubular member, the variation in press-fitting load is large, while the both ends of the outer spline formed on the shaft member are In a state where the inner spline is protruded from the end of the inner spline formed in the tubular member in the axial direction, the inner spline is not damaged on the distal end side of the outer spline, and therefore, the variation in the press-fit fitting load is small.
[0016]
That is, a force of a predetermined value or more acts in the axial direction of the power transmission device, and the shaft member and the tubular member move in the axial direction while receiving frictional resistance by the spline joint, thereby absorbing the impact energy in the axial direction. In this case, the magnitude of the frictional resistance corresponds to the press-fitting load when the press-fitting is further performed from the initial state where the shaft member and the tubular member are connected. This is a load in a substantially flat region with a small amount. That is, the press-fitting fitting load, that is, the frictional resistance is less varied than the peak value.
[0017]
For this reason, when a force of a predetermined value or more is applied in the axial direction of the power transmission device, the outer spline formed on the shaft member and the inner spline formed on the tubular member relatively move in the axial direction while receiving frictional resistance. Thus, when absorbing the impact energy in the axial direction, the frictional resistance of the spline joint is small and stable.
[0018]
Therefore, it is possible to obtain a power transmission device capable of absorbing the impact, which can absorb the impact energy by the stable frictional resistance of the spline joint.
[0019]
According to a second aspect of the present invention, either or both of the outer spline formed on the shaft member and the inner spline formed on the tubular member are helical splines, so that the gap in the tooth width direction of the spline is reduced. It can be made small, and rattling in the rotational direction of the power transmission device is prevented.
[0020]
According to the invention described in claim 3, since the outer spline formed on the shaft member is a helical spline, the processing of the spline can be performed compared to the case where the inner spline formed on the tubular member is a helical spline. It becomes easy.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0022]
FIG. 1 is a cross-sectional view showing a main part of a power transmission device capable of absorbing shock according to the present invention. FIG. 2 shows a state before the shaft member shown in FIG. B), FIG. 3 is a load characteristic showing the relationship between the press-fitting load and the press-fitting stroke when the outer spline formed on the shaft member shown in FIG. 1 is press-fitted to the inner spline formed on the tubular member. FIG.
[0023]
In the figure, 1 is a shaft member of the power transmission device, and 2 is a tubular member fitted to the shaft member 1. The shaft member 1 and the tubular member 2 are connected by a spline joint 3 so as to be relatively movable in the axial direction and not to be relatively rotatable in the rotational direction. That is, the outer spline 3a is formed on the shaft member 1, and the inner spline 3b is formed on the tubular member 2, and they are press-fitted together.
[0024]
The outer spline 3a formed on the shaft member 1 is formed in parallel to the axial direction, and its axial length is a dimension a. Further, the inner spline 3b formed on the tubular member 2 is formed in parallel to the axial direction, and the axial length thereof is a dimension b (see FIG. 2). The formation dimension a of the outer spline 3a formed on the shaft member 1 is longer than the formation dimension b of the inner spline 3b formed on the tubular member 2, whereby the shaft member 1 and the tubular member 2 are connected. In the initial state, both ends of the outer spline 3a are press-fitted and fitted so as to protrude from the end of the inner spline 3b in the axial direction (see FIG. 1).
[0025]
Here, as shown in FIG. 3, the load in which the outer spline 3a formed on the shaft member 1 is press-fitted into the inner spline 3b formed on the tubular member 2 is axially applied to the inner spline 3b. It increases linearly as it is press-fitted to, and when it reaches the peak value A1 when the tip of the outer spline 3a exits the inner spline 3b, it slightly decreases and changes from B1 to C1 substantially flatly. A characteristic with a region is shown. These press-fit load characteristics change as indicated by broken lines when the dimensions of the outer spline 3a and the inner spline 3b vary within an allowable range, and the respective loads become A2, B2, and C2. Show properties.
[0026]
Here, the difference in the press-fitting fitting load is that the mutual difference (P1) between the peak values A1 and A2 is relatively large, and the mutual difference (P2) between the loads B1 and B2 and C1 and C2 in a substantially flat region is relatively large. It will be small. That is, when the front end of the outer spline 3a formed on the shaft member 1 is in the axial direction of the inner spline 3b formed on the tubular member 2, the press-fitting load varies greatly, while the outer spline 3a is formed on the shaft member 1. In the state where both ends of the outer spline 3a protrude in the axial direction from the end of the inner spline 3b formed on the tubular member 2, the inner spline 3b is not damaged at the front end side of the outer spline 3a. The variation of is small.
[0027]
Reference numeral 4 denotes a tube that controls power transmission. The tube 4 is made of a metal material, a fiber-reinforced synthetic resin material, or the like, and is attached to the end of the tubular member 2, that is, the right end 5A in FIG. Specifically, the outer circumference of the right end portion 5A of the tubular member 2 is reduced in diameter by a dimension substantially equal to the wall thickness of the tube 4 over a predetermined length, and the end portion of the tube 4 is a tubular member. It is press-fitted into the outer peripheral portion with a reduced diameter of the second end portion 5A and is attached by welding or adhesion.
[0028]
According to such a configuration, the outer spline 3a formed on the shaft member 1 is press-fitted from the left end portion 5B side into the inner spline 3b formed on the tubular member 2, and the shaft member 1 and the tubular member 2 are connected. They are connected so that they can move relative to each other in the axial direction and cannot rotate in the rotational direction. At this time, the outer spline 3a of the shaft member 1 is formed longer in the axial direction than the inner spline 3b of the tubular member 2, and in the initial state where the shaft member 1 and the tubular member 2 are coupled, The both ends of the formed outer spline 3a are press-fitted and fitted so as to protrude in the axial direction from the end of the inner spline 3b formed on the tubular member 2. As a result, a power transmission device connected by the spline joint 3 is formed.
[0029]
In the power transmission device, the shaft member 1 is connected to a driving device (not shown), and the tubular member 2 is connected to a driving device (not shown) via a tube 4 between the driving device and the driven device. It manages the power transmission of the rotational torque. Further, when a force of a predetermined value or more is applied in the axial direction of the power transmission device, the shaft member 1 and the tubular member 2 are moved relative to each other in the axial direction while receiving frictional resistance by the spline joint 3. Absorbs directional impact energy.
[0030]
Here, the load that the outer spline 3a formed on the shaft member 1 is press-fitted into the inner spline 3b formed on the tubular member 2 is, as described above with reference to FIG. 3, the tip of the outer spline 3a is the inner spline 3b. 3 shows a characteristic having a region in which the peak value A1 (A2) is slightly reduced after the peak value A1 (A2) is exited and changes from B1 (B2) to C1 (C2) substantially flatly. The load characteristic line shown in FIG. The mutual difference (P2) between the loads B1, B2 and C1, C2 in the substantially flat region in the figure is relatively small. That is, when both ends of the outer spline 3a formed on the shaft member 1 protrude in the axial direction from the end of the inner spline 3b formed on the tubular member 2, the inner spline 3b is damaged on the tip side of the outer spline 3a. Therefore, the variation of the press-fit fitting load is small.
[0031]
That is, a force of a predetermined value or more acts in the axial direction of the power transmission device, and the shaft member 1 and the tubular member 2 move relative to each other in the axial direction while receiving a frictional resistance by the spline joint 3, thereby causing an axial impact. When absorbing energy, the magnitude of the frictional resistance corresponds to the press-fitting load when the shaft member 1 and the tubular member 2 are further press-fitted from the initial state. It becomes a load in a substantially flat region where there is little change in the fitting load. That is, the press-fitting fitting load, that is, the frictional resistance is less varied than the peak value.
[0032]
Therefore, when a force of a predetermined value or more is applied in the axial direction of the power transmission device, the outer spline 3a formed on the shaft member 1 and the inner spline 3b formed on the tubular member 2 are subjected to frictional resistance in the axial direction. The frictional resistance of the spline joint 3 has a small variation and becomes stable when absorbing the impact energy in the axial direction.
[0033]
Therefore, it is possible to obtain a power transmission device capable of absorbing the impact by absorbing the impact energy by the stable frictional resistance of the spline joint 3.
[0034]
FIGS. 4 to 6 are views showing other embodiments of the present invention. The difference between these embodiments is that the outer splines 3a formed on the shaft member 1 and the tubular member 2 are formed. One or both of the inner splines 3b are helical splines. Hereinafter, these embodiments will be described. In the description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.
[0035]
First, in the embodiment shown in FIG. 4, the outer spline 3a formed on the shaft member 1 is a spline parallel to the axial direction, and the inner spline 3b formed on the tubular member 2 is a helical spline.
[0036]
In the embodiment shown in FIG. 5, the outer spline 3a formed on the shaft member 1 is a helical spline, and the inner spline 3b formed on the tubular member 2 is a spline parallel to the axial direction.
[0037]
In the embodiment shown in FIG. 6, both the outer spline 3a formed on the shaft member 1 and the inner spline 3b formed on the tubular member 2 are helical splines.
[0038]
Also in such a configuration, in the initial state where the shaft member 1 and the tubular member 2 are connected, both ends of the outer spline 3a formed on the shaft member 1 are axially directed from the end of the inner spline 3b formed on the tubular member 2. Therefore, when a force of a predetermined value or more acts in the axial direction of the power transmission device to absorb the impact energy, the frictional resistance of the spline joint 3 is small and stable.
[0039]
Therefore, also in these embodiments, a power transmission device capable of absorbing the impact and capable of absorbing the impact energy by the stable frictional resistance of the spline joint 3 can be obtained.
[0040]
In addition, since one or both of the outer spline 3a formed on the shaft member 1 and the inner spline 3b formed on the tubular member 2 are helical splines, the clearance in the tooth width direction of the splines 3a and 3b can be reduced. Further, rattling in the rotational direction of the power transmission device is prevented.
[0041]
In particular, by forming the outer spline 3a formed on the shaft member 1 as a helical spline, the spline can be easily processed as compared with the case where the inner spline 3b formed on the tubular member 2 is a helical spline.
[0042]
Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment and can be changed without departing from the gist of the invention.
[0043]
【The invention's effect】
As described above in detail, according to the present invention, a power transmission device capable of absorbing an impact and capable of absorbing the impact energy by a stable frictional resistance of the spline joint can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a power transmission device capable of absorbing shock according to the present invention.
FIG. 2 is an explanatory view showing a state before the shaft member shown in FIG. 1 is fitted to the tubular member by a shaft member (A) and a tubular member (B).
FIG. 3 is a load characteristic diagram showing a relationship between a press-fitting load and a press-fitting stroke when the outer spline formed on the shaft member shown in FIG. 1 is press-fitted to the inner spline formed on the tubular member.
FIG. 4 is a view similar to FIG. 2, showing another embodiment of the present invention.
FIG. 5 is a view similar to FIG. 2, showing another embodiment of the present invention.
FIG. 6 is a view similar to FIG. 2, showing another embodiment of the present invention.
[Explanation of symbols]
1 Shaft member 2 Tubular member 3 Spline joint 3a Outer spline 3b Inner spline 4 Tube

Claims (3)

In a power transmission device capable of absorbing an impact, wherein a shaft member and a tubular member fitted to the shaft member are connected to each other by a spline joint so as to be relatively movable in the axial direction and not to be relatively rotatable in the rotational direction.
The outer spline formed on the shaft member is press-fitted to the inner spline formed on the tubular member,
The outer spline formed on the shaft member is formed longer in the axial direction than the inner spline formed on the tubular member,
In the initial state where the shaft member and the tubular member are connected, both ends of the outer spline formed on the shaft member protrude in the axial direction from the end of the inner spline formed on the tubular member, and can absorb shocks. Power transmission device. The power transmission device capable of absorbing an impact according to claim 1, wherein one or both of an outer spline formed on the shaft member and an inner spline formed on the tubular member are helical splines. The power transmission device capable of absorbing shock according to claim 2, wherein the outer spline formed on the shaft member is a helical spline.

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