JPH0135092Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a wrap-around transmission device using a toothed belt. Specifically, the invention relates to a toothed belt in which the drive pulley is driven under low-speed, high-torque conditions such as manual rotation drive. This invention relates to a wrap-around transmission device using.

[Conventional technology]

In response to the demand for stepless adjustment of the angle of the backrest of a reclining seat, it was proposed and implemented that the angle of the backrest of a reclining seat be adjusted using a wrap-around transmission mechanism using a toothed belt instead of the conventional ratchet mechanism. is being attempted.

That is, as shown in FIG. 6, a toothed pulley B is provided on the central axis of rotation of the backrest portion _A1 of the reclining seat A, and a toothed belt is connected to the toothed pulley B and the manually driven toothed pulley C. By winding D and operating this drive pulley C, the backrest part A ₁
This is an attempt to adjust the slope of the

The toothed belt adjustment device described above is quieter than conventional ratchet mechanisms. Another advantage is that since no slip occurs between the belt and the pulley, a locking effect similar to that of a ratchet device can be obtained by applying a brake to the drive pulley.

[Problems with conventional technology]

However, if you unknowingly apply rotational force to the drive pulley after the backrest of the reclining seat has been reclined to its maximum or upright position,
Excessive rotational force may cause the toothed belt to skip on the driven pulley or the driving pulley, causing tooth chipping due to local stress generated in the teeth of the toothed belt, significantly shortening the belt's service life. There is a problem that has caused a loss.

Moreover, since toothed belts are generally made of rubber-like elastic material, even when the driven pulley is at rest, the elastic deformation of the teeth makes it difficult for the driving pulley to feel the sense of stopping, making it easy to apply excessive rotational force. I have a problem.

Furthermore, when fixing a backrest that has been adjusted and fixed at an arbitrary angle by fixing a toothed belt that meshes with a driven pulley, if the load applied to the backrest is large, the toothed belt will skip relative to the driven pulley. There are some problems that occur.

However, as a device for preventing the skipping phenomenon of the toothed belt and ensuring reliable meshing transmission, an arc-shaped belt holding plate is attached to the outside of the toothed belt, as disclosed in, for example, Japanese Utility Model Application Publication No. 161157/1983. There is a known method in which the parts are arranged with a small gap between them.

However, since these methods merely prevent the toothed belt from skipping, they pose the following problems.

In other words, in the case of the above-mentioned wrap-around transmission device intended for low-speed, high-torque transmission, when a high load is applied quietly, the toothed belt cannot be prevented from lifting up by the separation distance of the belt holder. Shear deformation of the teeth and resulting transmission loss occur. Therefore, in order to provide strength and rigidity against this shear stress, it is necessary to increase the width of the toothed belt, which makes it difficult to downsize the device and increases rotational resistance due to the rigidity.

Therefore, there was a problem that it could not be used as a low-speed, high-torque transmission device.

[Problem that the invention attempts to solve]

In view of the above-mentioned problems, this invention significantly reduces the belt width, making the entire device more compact and reducing the resistance.This design also enables winding using a toothed belt that can be used under low speed and high torque conditions. It was made for the purpose of providing a hanging transmission device.

[Technology that led to solving the problem]

The wrapped transmission device using a toothed belt of this invention has a highly elastic core embedded inside between a toothed pulley driven at low speed and high torque and a toothed pulley attached to a driven rotating shaft. A toothed belt whose main body is made of a highly elastic material is wound around the toothed pulley on the smaller diameter pulley of the driving or driven side toothed pulley, or preferably on both toothed pulleys. Along the outer peripheral surface of the back surface of the toothed belt, from the engagement start point to the engagement end point, a presser plate with an arcuate inner surface as a low friction layer is brought into contact with and fixed to the belt back surface without applying any pressing force. It is characterized in that it is arranged.

[Effect]

Next, the operation of this invention will be explained.

Generally, when a toothed belt is driven at low speed and high torque, the pulley teeth and the tooth surfaces of the belt teeth that contact them have a unique pressure angle (α in Figure 2), so the action of circumferential force F As a result, the toothed belt receives a force trying to push it up by the pulley teeth [shown in Figure 2].
F _R (=Fsinα)] force acts.

As a result, a phenomenon occurs in which the toothed belt is lifted from the toothed pulley.

In the present invention, on the back surface of the toothed belt, a presser plate whose arc-shaped inner surface is a low-friction layer is pressed against the back surface of the belt along the outer peripheral surface from the engagement start point to the engagement end point with the toothed pulley. Since they are fixedly arranged in contact without applying pressure, the above-mentioned lifting phenomenon does not occur at all.

As a result, the toothed belt and the toothed pulley are always in contact over the entire surface of their respective tooth depths, and the shear strength of the teeth as a whole is exerted, and there is no loss of strength due to lifting of the teeth.

Therefore, it is possible to estimate the safety factor of the shear strength of the toothed belt to be low, and even if the belt width is narrowed, sufficient durable strength will be exhibited.

Furthermore, even if the driven pulley is in a braking state,
Since the toothed belt is made of a highly elastic core and a highly elastic material, it does not stretch, and since the feeling of stopping is reliably transmitted to the drive pulley, it is possible to prevent the drive-side toothed pulley from idling and over-rotating.

Furthermore, since the inner surface of the presser plate is a low-friction surface, even if the toothed belt is pressed against the inner surface of the presser plate by the radial force F _R , the sliding frictional resistance in the circumferential direction can be kept very low.

〔Example〕

Next, this invention will be explained using examples.

FIG. 1 is a side view of an embodiment of this invention.

Wrap transmission device 1 using toothed belt of this invention
has, for example, a handle or an operability notch 2A that is driven under low-speed, high-torque conditions, and there is an internal A highly elastic core body 5A made of non-stretchable fibers such as Kevlar, steel wire or glass fiber is embedded in the body 5B, and the body 5B is made of an elastomer having an elastomer hardness of JISA 78° or more, preferably
A toothed belt 5 made of a highly elastic material with JISA 82° to 92° is wound around it, and furthermore, at least on the side of the toothed pulley 4 on the driven shaft side, on the back side of the toothed belt 5 along the top of the toothed pulley 4. From the engagement starting point P to the ending point Q
A pressing plate 6 having a low-friction arc-shaped inner surface 6A is fixedly arranged on the base frame 7 along the outer circumferential surface up to the toothed belt 5 so as to be in contact with the back surface of the toothed belt 5 without applying any pressing force. There is.

In the above embodiment, the arc-shaped inner surface 6 of the presser plate 6
A is made of a low-friction resin such as ethylene, Teflon, nylon, or polyester, or a low-friction resin obtained by adding a friction-reducing material such as molybdenum disulfide to the above materials, an oil-impregnated synthetic resin, or FRP. Even when it comes into contact with the belt 5, almost no frictional resistance is generated.

Note that a low friction layer according to the above-mentioned items may also be provided on the back surface of the toothed belt 5.

Further, the holding plate 6 may also be provided on the drive pulley 2 side.

Although the driving device for a reclining seat has been described as the above embodiment, it can be similarly implemented as a device that requires low-speed, high-torque transmission, such as a power window driving device for an automobile.

Next, using the apparatus shown in FIG. 3, the embodiment of the present invention was tested for skip occurrence and stop feeling, and the following results were obtained.

The test apparatus B shown in FIG. 3 has 50 teeth, with a toothed pulley 10 as a manually driven pulley, a 16-toothed pulley 11 as a driven pulley, and a toothed belt 5 mounted between these pulleys. Load 30 on pulley 11 side
Kg is applied, and an arcuate belt presser plate 6 is fixed along the outer periphery of the belt wound around the driven pulley.

The toothed belt 1 used Kevlar as a reinforcing core, and an elastomer having a hardness of JISA 80°.

Then, the drive pulley 10 was manually rotated so that it was stopped by the stop 12 when the driven pulley 11 had rotated 360 degrees, and the feeling of stopping was measured based on the manual torque ratio at that time.

FIG. 4 is a graph showing the results.

In Fig. 4, when a normal toothed belt without a presser plate is used, is a presser plate 6 and a toothed belt 1.
The clearance between the back and the belt tooth height is 3/3 of the belt tooth height.
The one provided in the part corresponding to 1 indicates an example of the present invention, and the vertical axis of the graph (hand cranking torque ratio) indicates a comparison value with the torque ratio of 1 as 1,
Compared to , the torque ratio increases to 5 and 10, respectively. In particular, in the embodiment of the present invention, the initial rise degree θ is large, indicating that a strong sense of stopping is transmitted to the steering wheel.

Next, since the presser plate 6 is always in contact with the back surface of the toothed belt 1, frictional resistance with the toothed belt becomes a problem. Therefore, when we measured the sliding resistance ratio (ratio when no sliding resistance is taken as 1) for various sliding materials, the results shown in the table below were obtained.

According to experiments conducted by the present inventors, the practical upper limit of the sliding resistance ratio appears to be about 5.0, and all the sliding materials listed in the table are applicable. However, due to maintenance issues such as prevention of rust, it is desirable to use a synthetic resin-based material, especially a composite material with a sliding additive. Note that similar results were obtained even when the above-mentioned sliding material was provided on the back surface of the toothed belt.

Table Sliding material Sliding resistance ratio Polyethylene 1.6 Teflon 1.0 Nylon 1.7 Polyester 2.2 Nylon + Graphite 1.0 〃 + Graphite 1.2 〃 + Mica 1.2 Oil-impregnated plastic 1.1 FRP 3.2 Iron 5.0 Aluminum 3.0 Next, the hardness and AE value of the belt (A: cross-sectional area,
E: Young's modulus, AE=F/ε, F...force, ε...strain amount)
Based on the correlation between the hardness that does not affect the rotational operating force and the strength of the circumferential resistance force when meshing with the toothed pulley, we conducted a test using the testing device shown in Figure 3, and found that the results shown in Figure 5 were as follows. The following results were obtained.

That is, in FIG. 5, the vertical axis of the graph shows the elastomer hardness of the toothed belt, and the horizontal axis shows the AE value (A: cross-sectional area, E: Young's modulus).

The toothed belt of the present invention is not suitable if the hardness is high because it requires operating force, but on the other hand, if the hardness is low, the elastic force will worsen the stopping feeling described above. Considering the compatibility between the two, it has been found that the range X/Y indicated by diagonal lines in the graph is preferable. The standard used to determine this range was determined by the change in hand torque ratio shown in FIG.

Note that belts with properties included in range X shown in Fig. 5 include ordinary toothed belts and range Y.
As the elastomer hardness approaches , the elastomer hardness increases and the longitudinal elastic modulus of the highly elastic core 5A shown in FIG. 1 is further increased.

〔effect〕

As mentioned above, this invention uses the presser plate on the back side of the part of the toothed belt that contacts the toothed pulley to prevent the belt from lifting off the toothed pulley, so the strength of the entire tooth is always exhibited. In addition, since skipping is reliably prevented, the strength safety factor of the toothed belt can be lowered, the width of the belt can be narrowed, and the entire apparatus can be made more compact.

Therefore, it can be used safely and reliably even when used for low-speed, high-torque transmission, such as a device for adjusting the inclination angle of the backrest of a reclining seat, and the presser plate only contacts the toothed belt without applying any pressing force. Because of this, there is almost no sliding resistance during normal operation, and it has various practical effects such as easy manual operation.

[Brief explanation of the drawing]

Fig. 1 is a side view of the embodiment, Fig. 2 is an explanatory diagram of the action, Fig. 3 is an explanatory diagram of the test device, Figs. 4 and 5 are graphs showing the test results, and Fig. 6 is an embodiment of the present invention. It is an explanatory diagram showing one example of use of.

Claims (1)

[Scope of utility model registration request] A toothed pulley that is driven under low speed and high torque conditions,
A highly elastic core body is embedded inside the toothed pulley attached to the driven rotating shaft, the main body is made of a highly elastic material, and a toothed belt is wound around the drive or driven side teeth. Of the pulleys with a small diameter, or preferably with both toothed pulleys, an arcuate inner surface is formed along the outer peripheral surface of the back surface of the toothed belt along the toothed pulley from the engagement start point to the engagement end point. A winding transmission device using a toothed belt, characterized in that a presser plate having a low friction layer is fixedly arranged in contact with the back surface of the belt without applying any pressing force.