JPH029973Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a platen variable device for a typewriter, and more specifically, the entire ratchet gear that meshes with the main body drive device and transmits a powerful driving force from the main body drive device is formed of sintered metal. The present invention also relates to a platen variable ratchet wheel gear for a typewriter, in which a bearing is slidably received on the inner wall of the center hole of the ratchet gear through which the platen shaft is inserted, thereby preventing deformation wear and shaft runout of the ratchet gear.

Line space feed of the typewriter is automatically performed by a drive pawl acting on a ratchet gear provided on the platen shaft.

The conventional ratchet gear, as shown in Figure 1,
A ratchet wheel 12 is made of synthetic resin and is slidably and rotatably formed on the platen shaft 10 and engages the platen knob in serrations in a detachable manner. A sintered metal ratchet gear 14 is insert-molded with the ratchet wheel 12. The ratchet wheel 12 is also formed with a recess 16 for inserting a spring that presses the ratchet wheel 12 toward the platen knob, and a metal bearing 18 is inserted into the recess 16 with a slight gap between it and the inner peripheral surface of the recess 16. has been done.

However, in the above-mentioned line space feed, the drive pawl acts on the ratchet gear 14 which is always in a stationary state, and a strong driving force is always transmitted to the ratchet gear 14 intermittently. Metallic ratchet gear 1
4, there is a problem that the ratchet gear 14 cannot resist the driving force applied from the direction of arrow A, and the ratchet gear 14 may be deformed or damaged. Furthermore, a metal bearing 18 that receives a ratchet wheel 12 made of synthetic resin is attached to the recess 1.
Since there is a gap between the inner peripheral surface of the platen shaft 10 and the ratchet gear 14, the driving force causes the ratchet wheel 12 and the ratchet gear 14 to axially run out relative to the platen shaft 10, which not only promotes deformation of the ratchet gear 14, but also There is also the problem that the inner circumferential surface of the resin-made recess 16 may be damaged or worn.

The present invention was developed in view of the above-mentioned difficulties, and its purpose is to provide a synthetic resin ratchet wheel integrally equipped with a ratchet gear linked to the drive mechanism of the typewriter body, which can effectively prevent deformation of the ratchet gear. The ratchet wheel is slidably and rotatably provided on a platen shaft connected to the platen, and the ratchet wheel is brought into serration engagement with the platen knob fixed to the platen shaft by the urging force of a spring, and the ratchet wheel is slidably and rotatably mounted on a platen shaft connected to the platen shaft. In a platen variable device in which a wheel is slid on a platen shaft to release the serration engagement, a ratchet wheel 28 is inserted into each of a plurality of through holes 40 provided in the end face of the ratchet gear 36. The boss 42 formed on the side surface of the platen knob 20 is fitted into the hub 42 so that the ratchet gear 36 and the ratchet wheel 28 are integrated, and a central recess formed at the side end of the integrally provided ratchet gear 36 and the ratchet wheel 28 opposite to the platen knob 20 is formed. The ratchet gear 36 is formed of sintered metal from its cutting edge toward the platen shaft 26 to the central recess, and a bearing 44 is provided that moves while closely sliding against the wall surface formed of the sintered metal of the central recess. is slidably provided on the platen shaft 26, and the bearing 4
A spring 48 is inserted between the rear wall of the center concave portion and the inner surface of the ratchet gear 36, and when the ratchet wheel 28 engages the platen knob 20 in a serration manner due to the biasing force of the spring 48, the bearing 44 is placed in a position corresponding to the inner circumferential surface of the ratchet gear 36. Platen shaft 2
To provide a platen variable ratchet wheel gear for a typewriter, characterized in that sliding of a bearing 44 in a direction opposite to the center recess on a typewriter is restricted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the figure, reference numeral 20 denotes a platen knob made of synthetic resin, which has a wheel penetration hole 22 and a button penetration hole 24, and is integrally insert-molded with a metal platen shaft 26 protruding through its axial center. A male threaded portion provided in the section allows the device to be screwed onto the center shaft of a platen (not shown).

Reference numeral 28 denotes a synthetic resin ratchet wheel having a substantially trapezoidal cross section, which has a through hole 30 in its center and is slidably and rotatably mounted on the platen shaft 26. Further, the diameter of the through hole 30 on the side opposite to the platen knob 20 is enlarged to form a circular hole 32 . A serration 34 is formed on the outer peripheral surface of the ratchet wheel 28, and is adapted to engage with the inner peripheral wall of the wheel penetration hole 22 of the platen knob 20.

Reference numeral 36 denotes a ratchet gear made entirely of sintered metal, which is fixed to the end face of the ratchet wheel 28 on the side opposite to the platen knob 20. A through hole 38 having the same diameter as the circular hole 32 of the ratchet wheel 28 is provided in the center of the ratchet gear. The platen shaft 26 is configured to slide integrally with the ratchet wheel 28 on the platen shaft 26, and is rotatable about the platen shaft 26.

As shown in FIG. 3, the end face of the ratchet gear 36 is formed integrally with the ratchet wheel 28 by insert-molding a suitable number of small-diameter through holes 40, as shown in FIG.
2 are fitted together, so the ratchet gear 36 and the ratchet wheel 28 are firmly fixed.

In this way, the ratchet wheel 2 is inserted into the plurality of through holes 40 provided in the end face of the ratchet gear 36.
By fitting the boss 42 on the side of 8,
Both can be fixed together without using screws or the like.

This eliminates the concern that the ratchet gear 36 and the ratchet wheel 28 may become loose due to enlargement of the screw holes or loosening of the screws during use of the typewriter, which would occur when the two are fixed together with screws or the like. can do.

Reference numeral 44 denotes a bearing, which is mounted so as to be slidable on the platen shaft 26. The outer diameter of the bearing 44 is formed to be the same diameter as the through hole 38 provided in the ratchet gear 36, and the bearing 44 can move within the through hole 38 and the circular hole 32 while closely sliding in contact with the inner wall thereof. ing. Note that the bearing 44 can be constructed of a metal washer, a thrust bearing, or the like.

46 is an E ring, and the platen shaft 26
This restricts the bearing 44 to remain within the through hole 38.

A coil spring 48 is inserted between the bearing 44 and the bottom of the circular hole 32, and urges the ratchet wheel 28 toward the platen knob 20.
As described above, the ratchet wheel 28 and the platen knob 20 are engaged in serration engagement.

During this engagement, the ratchet gear 36 is connected to a drive mechanism of the typewriter body (not shown). Also, during this engagement, the bearing 44
is set to be in sliding contact with the inner peripheral surface of the ratchet gear 34.

48 is a push button, and when this push button 48 is pushed in the direction of the ratchet wheel 28, the tip of a push rod 50 protruding from the push button 48 comes into contact with the end surface of the ratchet wheel 28, causing the ratchet wheel 28 to resist the biasing force of the coil spring 48. The serration engagement between the ratchet wheel 28 and the platen knob 20 is released by pressing it toward the side opposite to the platen knob 20. Note that 52 is a reinforcing rib arranged radially within the button penetration hole 24, and also serves as a stopper for the push button 48.

Next, the operation of this embodiment will be explained.

As mentioned above, normally the coil spring 48
The resiliency of the ratchet wheel 28 brings it into serration engagement with the platen knob 20, and the ratchet gear 28 engages with a drive pawl on the typewriter body. At this time, the bearing 44 is connected to the coil spring 48.
It is pressed to contact the E-ring 46 by its elasticity, and at this position it contacts and receives the inner peripheral surface of the through hole 38 of the ratchet gear 36 made of sintered metal. Therefore, the ratchet wheel 28 and the ratchet gear 36 are supported in a bridge manner by the bearing 44 and the bottom wall of the ratchet wheel 28 with respect to the platen shaft 26.

Therefore, even if a strong driving force is applied to the ratchet gear 28 from the drive claw of the typewriter, this driving force is applied to the ratchet gear 36 made of sintered metal.
It is transmitted to the platen shaft 26 from the vertical direction via the main body and the bearing 44 inscribed therein, and is received therein, thereby preventing deformation of the ratchet gear 36.

Further, since the ratchet wheel 28 and the ratchet gear 36 are supported by the platen shaft 26 in a bridge state as described above, so-called axial vibration does not occur even when the strong driving force is applied.

Next, when the push button 48 is pressed, the ratchet wheel 28 and platen knob 2 are moved as described above.
0 is released, the platen knob 20 becomes free from the main body drive mechanism, and by rotating the platen knob 20, the platen (not shown) is rotated to a desired position via the platen shaft 26. be able to. By pressing this push button 48, the ratchet gear 3
6 slides on the bearing 44 in the direction opposite to the platen knob 20. However, since the entire ratchet gear 36 is made of sintered metal, the inner peripheral surface will not be easily damaged or worn, and the outer peripheral surface of the bearing 44 will slide on the bearing 44. It can always operate accurately without any play between the two.

As described above, according to the present invention, the ratchet gear is formed of sintered metal and its inner peripheral surface is received on the platen shaft by a bearing.
The ratchet gear does not deform even when a strong driving force is applied from the main body drive device, and the inner peripheral surface of the ratchet gear is not easily damaged or worn out, making it extremely durable and ensuring accurate operation at all times. Effective.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a conventional ratchet wheel and ratchet gear, FIG. 2 is a sectional view of a variable device incorporating the ratchet wheel according to the present invention, and FIG. 3 is a front view showing the ratchet gear. 10... platen shaft, 12... ratchet wheel, 14... ratchet gear, 16...
Recessed portion, 18... bearing, 20... platen knob, 2
2...Wheel penetration hole, 24...Button penetration hole,
26... platen shaft, 28... ratchet wheel, 30... through hole, 32... circular hole, 34...
...Serration, 36...Rachietsu Gear, 38
...Through hole, 40...Through hole, 44...Bearing, 46...
...E ring, 48...Push button, 50...
Pressing rod, 52...Reinforcement rib.

Claims (1)

[Scope of utility model registration request] A synthetic resin ratchet wheel integrally provided with a ratchet gear connected to the drive mechanism of the typewriter body is slidably and rotatably provided on a platen shaft connected to the platen, and the ratchet wheel is attached to the platen shaft. A platen variable device in which the serration is engaged with a platen knob fixed to the platen by the biasing force of a spring, and the ratchet wheel is slid on the platen shaft by operating a push button to release the serration engagement. In this case, a boss 42 formed on the side surface of the ratchet wheel 28 is fitted into each of a plurality of through holes 40 provided in the end face of the ratchet gear 36, so that the ratchet gear 36 and the ratchet wheel 28
The ratchet gear 36 and the ratchet wheel 28, which are integrally provided, have a central recess that opens at the end on the side opposite to the platen knob 20, and the ratchet gear 36 connects the platen shaft 26 from its cutting edge.
A bearing 44 is slidably provided on the platen shaft 26, and is made of sintered metal up to the central recess in the central recess, and moves in close sliding contact with the wall surface formed of the sintered metal in the central recess. A spring 48 is inserted between the bearing 44 and the inner wall of the center recess, and when the ratchet wheel 28 is serration engaged with the platen knob 20 due to the biasing force of the spring 48, the bearing 44 is pressed against the inner peripheral surface of the ratchet gear 36. Place the platen shaft 26 in the corresponding position.
A platen variable ratchet wheel gear for a typewriter, characterized in that sliding of a bearing 44 in the direction opposite to the center recess at the top is restricted.