JPS639768Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an improved structure of an overload prevention transmission means in which a shaft and a cylindrical body loosely attached to the shaft are connected by a shear pin that shears when a load exceeding a set value is applied. Conventional technologies for the above-mentioned transmission means include the one shown in Fig. 5 and the one found in Publication of Utility Model Publication No. 48-45543, but all of these conventional technologies have The insertion hole that is opened through the insertion hole is made to have the same diameter as a whole, and the shear pin that is inserted through it is also formed so that the entire diameter is approximately the same as that of the insertion hole, so that the shear pin and the insertion hole are tightly fitted. It has a structure that fits together. Therefore, with the conventional structure, the limit torque cannot be changed unless the diameter of the insertion hole made through the shaft and the cylinder and the diameter of the shear pin are changed. There is a drawback in that it requires major changes throughout the process.
The problem was that the scope of application was limited. The present invention was implemented with the aim of resolving the above-mentioned difficulties.It is easy to change and set the limit torque in various ways, and the safety of the overload prevention transmission means has been improved so that it can be used in a wide range of applications. It provides a pin structure. That is, the present invention provides an overload prevention transmission means in which a cylindrical body 2 is loosely attached to a shaft 1 and connected by a shear pin 4 passing through both 1 and 2 in the diametrical direction. The hole diameter in the second part of the cylinder is the same as or larger than the hole diameter in the first part of the shaft,
Moreover, the safety pin structure is such that there is a difference in size between the hole diameters on both sides in the axial and radial direction in the cylindrical body 2 portion. Next, a specific example of the present invention will be explained with reference to the drawings. The present invention includes an insertion hole 3 that is opened diametrically across a shaft 1 and a cylindrical body (boss portion 2 of a gear, sprocket, etc.) that is loosely attached to the shaft; A feature is that the shear pin 4 is not tightly inserted. In other words, the insertion hole 3 is formed to have a diameter slightly larger than the outer diameter of the shear pin 4, and the hole diameter of the portion formed in the cylinder body 2 is the same or larger than the hole diameter of the portion formed in the shaft 1. In addition, the diameter of the hole on both sides of the shaft 1 in the cylinder body 2 is made to have a size difference, and by adjusting the difference in the diameter of the hole on both sides of the shaft in the cylinder body 2, various limit torques can be adjusted. We are trying to get a value. The diameters of the holes on both sides in the radial direction of the cylinder body are larger than the diameters of the holes formed in the shaft 1 part, and there is a difference between the diameters of the holes on both sides of the cylinder body in the radial direction. In between, a gap with a diameter difference appears on both sides in the radial direction of the shaft, and when an overload is applied, the shaft 1 or the cylinder body 2 jumps and a kind of impact force is generated, and that impact force load is applied to the shear pin 4. There is a correlation between the size difference in the gap on both sides in the axial and radial direction of the cylinder body 2 and the impact force applied to the shear pin 4, and the size of the impact force depends on the size of the gap difference. This has been confirmed through experiments as follows.

[Table] As will be clear from this, the larger the difference in diameter between the two sides of the insertion hole on the shaft side, the greater the impact force and the smaller the shearing torque. By adjusting the difference in hole diameter, overload can be prevented. The limit torque of the transmission means can be freely set to a desired value. In addition, the insertion hole opened on the side of the cylinder 2 is not limited to a round hole, and in some cases, it may be formed into a long hole that is long in the direction of rotation as shown in FIG. 4. It is. In short, the present invention provides an overload prevention transmission means in which a cylindrical body 2 is loosely attached to a shaft 1 and connected by a shear pin 4 passing through both 1 and 2 in the diametrical direction. The hole diameter in the second part of the cylinder is the same as or larger than the hole diameter in the first part of the shaft,
In addition, since the safety pin structure is made such that there is a size difference between the hole diameters on both sides in the axial and radial direction of the cylinder body 2, as is clear from the above experimental results, the hole diameter on the cylinder body 2 side The limit torque value can be arbitrarily changed and set simply by setting various differences, and the range of application can be expanded and used conveniently while reducing costs. Furthermore, since the insertion hole 2 has a diameter difference between the shaft 1 and the cylinder 2, the impact force applied to the shear pin 4 is transmitted to the fitting surface between the shaft 1 and the cylinder 2. Since the maximum torque is applied directly to the shear pin 4, there is no variation in shear pin breakage at the set limit torque, and the transmission is accurately interrupted at the appropriate time. There are some advantages.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the main structure of the present invention;
The figure is a cross-sectional view similar to Figure 1 showing the case where the hole diameter of the insertion hole on the cylinder side is changed, Figure 3 is a cross-sectional view taken along the line A-A in Figure 1, Figure 4 is an explanatory diagram of a modification, and Figure 4 is a diagram for explaining a modification. FIG. 5 is an explanatory diagram of a conventional structure. 1...Shaft, 2...Cylinder, 3...Insertion hole, 4...
shear pin.

Claims (1)

[Scope of utility model registration request] In an overload prevention transmission means in which a cylindrical body 2 is loosely fitted onto a shaft 1 and connected by a shear pin 4 passing through both 1 and 2 in the diametrical direction, an insertion hole 3 through which the shear pin 4 is inserted is formed in a portion of the cylindrical body 2. The diameter of the hole is the same as or larger than the diameter of the hole in the first part of the shaft, and the diameter of the hole on both sides in the radial direction of the shaft in the second part of the cylinder is opened so as to be different in size. Safety pin structure inserted into shafts.