JPS6037341B2 - Reverse rotation prevention gear mechanism for watches, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mechanism for preventing reverse transmission in a gear train, which is suitable for use in, for example, a hand-type timepiece driven by a step motor.

In the above-mentioned watches, torque is normally transmitted from the rotor pinion of the motor to the mackerel row, but when the hands are set by the crown, or when an impact force is applied to the watch, the single weight on the pointer becomes the driving force. When trying to rotate the gear train, the gear train gear tries to turn the rotor pinion in the opposite direction.

Since this tendency of reverse transmission is undesirable as it causes a time error, various tooth profiles have been proposed to prevent this. Hereinafter, of the two mutually meshing gears forming the anti-reverse gear mechanism, the normal drive side (for example, rotor pinion) will be described as the A gear, and the normal driven side as the B gear. In the conventional reverse transmission prevention gear mechanism, for example,
1. As shown in Tokusekki Sho 52-106061, only during reverse transmission, the stress direction from the tooth surface of the B gear to the tooth surface of the A gear is directed within the friction stopping range, and the tooth tips of the A gear and the teeth of the B gear are Each tooth is formed so as to create tension between it and the tip, and the method is to compare the pitch of the A gear with the pitch of the B gear within a range that does not interfere with normal forward transmission rotational operation. This is done by increasing the size of the tooth tip of the A gear, or in addition, by making the tooth tip of the A gear almost flat so that the range in which tension is generated at the tooth tip is wider, compared to the conventional reverse transmission prevention where the range is equal for each tooth. In a gear mechanism, in order to maximize the range, the number of teeth existing in the meshing interference range (the range commonly included within the outer circumferential circle of the tips of the two gears) is normally set to the reduction gear train during transmission. In this case, the number of teeth in the A gear must be 2 or less, and the B gear must have 3 or less teeth, and the upper limit for the number of teeth in the A gear that can produce a practical tension has been 8. In a design where there are many teeth in the meshing interference range, the difference in the number of teeth between gears A and B within that range is always 1.
Therefore, the difference in pitch between the two gears, which is necessary for preventing reverse transmission, must be small. Also, the tooth thickness of the A gear is made thicker than the tooth thickness of the B gear to obtain a range in which tension is generated.For example, as shown in FIG. 7, if the number of teeth of the A gear 31 is increased by 1, The extension angle range 84 when 32 performs the reverse transmission rotation E is smaller than 0 in FIG. 2, which is the case where the A gear has eight teeth. This is because the radius of the A gear increases in the case of 10 teeth in order to keep the tooth thickness of the A gear the same in the case of 8 teeth and in the case of 1 tooth. In addition, since the range where the tension is generated is evenly distributed among the teeth, each range is narrow, so if the driving force transmission direction is reversed, the A gear will be statically pushed by the B gear. will always cause a tension, but in reality, if the A gear is kicked and goes ahead due to the impact force when reaching reverse rotation, etc., it will easily slip through without creating a tension and enter the range of motion.

Furthermore, at this time, the pitches of the A gear and the B gear are each constant, and the inertia of the B gear and the inertia of the magnets, etc. that rotate together with the A gear and the A gear make the pitch of both gears almost constant. As a result of being rotated at a constant speed, once the tension range is exceeded, the reverse transmission rotation will continue,
It was difficult to obtain a reliable reverse transmission prevention effect. The present invention aims to solve the above-mentioned drawbacks, and uses at least two types of teeth in which the opening width of each prong portion is approximately equal and different in tooth thickness, and the tooth thickness of the larger one of the teeth is increased. It is characterized by consisting of an A gear whose teeth are arranged so that they are not adjacent to each other, and a B gear which meshes with the A gear and has constant tooth thickness and tooth tip pitch,
By using at least two types of teeth with different tooth thicknesses in the A gear, the range in which tension is generated at the tip of the tooth with the larger tooth thickness is much wider than that of conventional gears with the same number of teeth, and the opposite Even if the A gear enters the movable range in advance during transmission, the pitch of the A gear varies depending on the location by approximately the difference in tooth thickness, that is, it cannot rotate at a uniform speed, so there is a range where tension occurs. As a result, the continuation of reverse transmission rotation is extremely difficult to occur, resulting in a difficult mechanism. In the case of the normal drive transmission direction, the gear train load resistance always acts on the B gear so that the B tooth surface is pressed in front of the A tooth surface, so the movement of the A gear which is not correctly pitched is also the same. Since the pitch is virtually unchanged from the conventional example, the rotation can be transmitted smoothly during normal transmission. Furthermore, by using the A gear in which teeth with larger tooth thickness and teeth with smaller tooth thickness are arranged alternately, during reverse transmission,
At least every other tooth has a certain tension, so
At the same time, it is possible to suppress the undesirable angle of rotation to the necessary minimum, and at the same time, it is easy to design an A gear with one or more teeth, for example, and when cutting a tooth profile, the cutter can cut two adjacent teeth with different thicknesses. It is easy to process them by considering them as a set of large teeth, and it is possible to provide a reverse transmission prevention gear mechanism that is highly complete not only from a mechanical standpoint but also from a manufacturing standpoint.

This will be explained below with reference to the drawings.

FIG. 1 is a plane showing the normal positive transmission meshing of tooth profiles in a conventional reverse transmission prevention gear mechanism composed of an A gear 1 with 8 teeth and a B gear 2 with 4 teeth meshing therewith. FIG. 3 shows a state in which the B gear 2 rotates counterclockwise as the A gear 1 rotates clockwise C.

FIG. 2 shows the limit position (A
It is a planar operation diagram showing the R part of the tip corner of gear 1 and the R part of the tip of B gear 2 with solid lines and imaginary lines.
8 indicates the tension range angle of the A gear 1.

Embodiments of the present invention are shown in FIG. 3 and below.

FIG. 3 shows an embodiment of the present invention, in which the opening widths of the respective tooth prongs 11a are approximately equal, and the teeth 11b4 have the larger tooth thickness.
It is composed of an A gear 11 with 8 teeth, in which teeth 1 and 1c with smaller tooth thickness are alternately arranged, and a B gear 12 with 48 teeth, each tooth having the same shape and meshing therewith. FIG. 3 is a plan view showing the positive transmission meshing, and shows a state in which the B gear 12 rotates to the left as the A gear 11 rotates clockwise. FIG. 4 is a plan view showing, by solid lines and imaginary lines, the limit position where tension occurs in the A gear 11 due to the reverse transmission rotation E' from the B gear 12 in the reverse transmission prevention gear mechanism, and 82 is an A The tension range angle in the gear 11 is shown, and although the number of teeth is the same as the conventional mechanism shown in FIG. 2, it has a much wider tension range angle a2. Furthermore, tension is relatively less likely to occur on the tooth 11c, which has a small tooth thickness.

FIG. 5 is a plan view of another embodiment of the present invention during normal forward transmission, and is a mechanism particularly suitable for a timepiece using a two-pole step motor. The opening width of each prong part 21a is approximately equal, and the teeth 21b having the larger tooth thickness and the teeth 21c having the tooth thickness of 4 and 5 are alternately arranged. FIG. 3 is a plan view showing the normal forward transmission meshing of tooth profiles in the reverse transmission prevention gear mechanism of the present invention, which is constituted by a rotor pinion 21 and a fifth gear 22 having 60 teeth that meshes with the rotor pinion 21. This shows a state in which the fifth gear 22 rotates counterclockwise D'' as the pinion 21 rotates clockwise C''.
FIG. 6 is a plan view showing, by solid lines and imaginary lines, the limit position at which tension is generated in the rotor pinion 21 due to the reverse transmission rotation E'' from the fifth gear 22 in the embodiment shown in FIG.
83 indicates the tension range angle of the rotor pinion 21, and even though the number of teeth of the rotor pinion 21 and the fifth gear 22 have been increased without changing the tooth ratio from the secondary example shown in FIG. , the tension range angle 8 has a wider tension range angle 83.

In a two-pole step motor, the rotor pinion rotates 180 degrees in one step.

In addition, the rotor is subjected to magnetic attraction by permanent magnets that attempt to stabilize the rotor in certain directions at angles of 180 degrees.

Therefore, unless the angle at which the rotor is rotated during reverse transmission is kept below 900 degrees, there is a risk that the rotor will be drawn into the adjacent stable position. In the previous embodiment, this angle was 900-82, which is smaller than 900, but in this embodiment, the number of teeth has increased, so it is even smaller, and the advantage is that tension always occurs when the rotation angle of the rotor pinion 21 is less than 1'5 rotations (72 degrees). There is. As mentioned above, in this simulation, the tension angle range, which was conventionally small because it was dispersed among the teeth of the drive side gear, is increased by consolidating it into a small number of teeth, and the reverse transmission prevention effect is statically reduced. Of course it was also dynamically ensured.

As a result, the angle from the start of the reverse transmission state to the occurrence of the first tension statically increases, but the increase can be kept within a range that does not cause any practical problems.

Furthermore, even if the number of teeth of the drive side gear was increased compared to the conventional example, a higher degree of safety in preventing reverse transmission could be obtained. In particular, it exhibited a remarkable safety effect even in two-hand watches, which had only one deceleration wheel (consisting of a coaxial pinion and gear) between the second gear with a large minute hand and the rotor pinion. .
Although the embodiments in which the present invention is applied to a timepiece have been mainly described above, the present invention can of course be applied to gear mechanisms of various machines whose purpose is to control rotation mainly when the direction of transmission changes depending on the tooth profile. It is.

In addition, although an example using only two types of teeth has been shown, it is possible to sandwich multiple thin teeth between the thick teeth, or even if the number and shape of the thin teeth to be sandwiched differ depending on the location. It is also clear that a plurality of tooth shapes may be allowed depending on the design conditions.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the meshing of tooth profiles in a conventional reverse transmission prevention gear mechanism during normal forward transmission, FIG. 2 is a plan view of the gear mechanism shown in FIG. 1 during reverse transmission operation, and FIG. - A plan view showing the meshing of the tooth profile in the embodiment during normal forward transmission, FIG. 4 is a plan view of the tooth profile during the reverse transmission operation of FIG. 3, and FIG. 5 is a normal view of the tooth profile in another embodiment of the present invention. Fig. 6 is a plan view showing the engagement during forward transmission, Fig. 6 is a plan view of Fig. 5 during reverse transmission operation, and Fig. 7 is a plan view showing the tooth profile of another conventional reverse transmission prevention gear mechanism during reverse transmission operation. FIG. 11, 21... Drive gear, 11a, 21a... Prong, 11b, 21b... Teeth having the larger gear in the drive gear, 11c, 21c... Drive gear Teeth with the smaller tooth thickness in, 12, 22
・・・・・・Driver gear. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1. At least two types of teeth are used in which the opening width of each prong portion is approximately equal and the tooth thickness is different, and the teeth having the larger tooth thickness among the teeth are not adjacent to each other. 1. A reverse transmission prevention gear mechanism for a watch, etc., comprising a driving gear disposed in a similar manner, and a driven gear meshing with the driving gear and having constant tooth thickness and tooth tip pitch. 2. A reversal prevention gear for a watch or the like as set forth in claim 1, wherein the driving gear is alternately arranged with two types of teeth: teeth with a large tooth thickness and teeth with a small tooth thickness. mechanism. 3. The driving gear mechanism is a rotor pinion of a two-pole step motor, and the driven gear is a gear of a deceleration wheel that meshes with the second gear supporting the minute hand. Reverse transmission prevention gear mechanism for watches, etc.