JPH04351365A - Plastic molded gear, drive device, and image forming device - Google Patents

Abstract

PURPOSE:To lessen gear transmission loss in a gear drive device and an image forming device. CONSTITUTION:A plastic molded gear according to the invention includes at least one helical gear G1 furnished with a gate for injection of plastic material upon the bearing boss end-face B on the side not receiving thrust load, wherein the dia. of another bearing boss end-face A receiving the reactive force to the thrust load is greater than the dia. of the first named end-face B. The gears G1, G2 are of helical type, and the thrust force acts thereon so that it is set off, but the thrust itself will remain.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin molded gear including at least one helical gear, and a drive device and an image forming apparatus using the same.

0002

2. Description of the Related Art Synthetic resin molded gears (hereinafter referred to as molded gears) have various characteristics such as excellent mass productivity, low cost, and low noise, and it goes without saying that they are widely used in various fields. Conventionally, in molded gears, attempts have been made to improve the pressure balance, uniformity of cooling rate, and gear precision by simultaneously filling all tooth tips with resin filled from the gate. One method is to provide several gates on the end face of the bearing boss. According to this method, the bearing boss portion is first filled with resin, and when the filled resin reaches the web portion, the filled resin simultaneously flows in the direction of all tooth tips, making it possible to mold a gear with high precision. In addition, in the case of a molded gear that has at least one helical gear, a thrust load is generated, and in many cases, the reaction force is received near the outer periphery of the end face of the bearing boss. Frictional force is generated in the circumferential direction at the contact area, resulting in torque loss. This torque loss decreases as the radius of the end face of the bearing boss is smaller, so the smaller the radius of the end face of the bearing boss is, the smaller the maximum load torque of the motor can be. Also, a large torque loss means a large load on the gear, but the teeth of the gear deflect due to the load, and the amount of deflection of the teeth changes with the meshing cycle, so the gear will change speed. Causes unevenness. In other words, when the torque loss increases, this rotational unevenness also increases, and in order to reduce the rotational unevenness of the gear, it is better to have a smaller torque loss.

0003

[Problems to be Solved by the Invention] However, in the conventional example described above, gear accuracy can be improved by providing several gates at the end of the bearing, but the wall thickness of this part is not suitable for providing gates. Yes (For example, in the case of POM, the gate diameter is preferably 60 to 70% of the wall thickness.) It cannot be made very thin. On the other hand, in order to reduce torque loss in the entire drive system, there was a dilemma: we wanted to make this part as thin as possible.

0004

[Means for Solving the Problems] In order to achieve the above object, the first aspect of the present invention is such that the diameter of the circle of the bearing boss end face (A) on the side receiving the reaction force of the thrust load is Manufactured by providing a synthetic resin injection gate on the bearing boss end face (B) on the side that is smaller than the diameter of the circle of the bearing boss end face (B) on the side that does not receive the thrust load and does not receive the reaction force of the thrust load. A synthetic resin molded gear including one or more helical gears characterized by:

A second aspect of the present invention is that the bearing boss end face (A) on the side receiving the thrust load reaction force and the bearing boss end face (B) on the side not receiving the thrust load reaction force have a bearing boss outer diameter. The chamfering amount of the bearing boss end face (A) on the side receiving the reaction force of the thrust load is approximately equal to the chamfering amount of the bearing boss end face (B) on the side not receiving the reaction force of the thrust load. A synthetic resin molded gear including one or more helical gears according to the first invention.

A third aspect of the present invention is a drive device equipped with a helical gear that slides and receives the reaction force of the thrust load of the gear on the end face of the bearing boss, wherein the helical gear receives the reaction force of the thrust load. The diameter of the circle of the bearing boss end face (A) on the side receiving the force is
Bearing boss end face on side that does not receive thrust load reaction force (B)
This drive device is manufactured by providing a synthetic resin injection gate on the bearing boss end face (B) on the side that is smaller than the diameter of the circle and does not receive the reaction force of the thrust load.

A fourth aspect of the present invention is an exposure device that exposes a photoreceptor drum, a device that performs an image forming process such as a primary charger including a photoreceptor, a developing device, a cleaning device, and a transfer device formed on the photoreceptor. The rotating body of the device is equipped with a paper feeding device that feeds the transfer material toward the image on the copy, a transfer device, a conveying section that sends the transfer material after transfer to the fixing device, and a fixing device, and the rotating body of the device is connected to the gear train from the motor. The image forming apparatus is driven through a bearing boss, and includes a helical gear that slides and receives the reaction force of the thrust of the gear on the end face of the bearing boss, and the helical gear receives the reaction force of the thrust load. The diameter of the circle of the bearing boss end face (A) on the receiving side is the same as that of the bearing boss end face (B) on the side that does not receive the reaction force of the thrust load.
), and is manufactured by providing a synthetic resin injection gate on the bearing boss end face (B) on the side that does not receive the reaction force of the thrust load. .

[0008]

【Example】

“Embodiment 1” FIG. 1 is a first embodiment that best represents the present invention. In the figure, the first gear G1 has a module M11.0, a number of teeth Z154, a helix angle β118°, and a leftward helix angle direction. It is. The second gear G2 is the module M21
．． 0, number of teeth Z227, helix angle β218°, left helix angle direction, and is integrally molded from synthetic resin. When this gear becomes one component of a certain drive device, the gear G
The thrust force Fx1 acting on gear G2 and the thrust force Fx2 acting on gear G2 act in directions that cancel each other out, but
Since the load applied to the teeth is larger on gear G2, the entire gear receives the force of FX2-FX1 and is used in the rotational direction of moving toward the A side in the figure. In the figure, the A side is chamfered with Ca, and the B side is chamfered with Cb. The outer diameter of the bearing boss 1 on both the A side and the B side is φD, and the diameter of the bearing boss end on the A side is φ
Da, the diameter of the bearing boss end on the B side is φDb, and Da
<Db. Furthermore, although it is better for the chamfer Ca to be as large as possible, the size and chamfer angle must be designed in consideration of the strength of the bearing boss and the surface pressure applied to the A side. A web 8 is provided in the axial direction of the bearing boss 1 in the shape of a flat plate.
A gear G1 is formed on the outer periphery of the web 8, and a gear G2 is formed on one side of the web 8.

As shown in the plan view of FIG. 2, gates g are provided at four locations on the end face B of the bearing boss. As shown in FIG. 1, the mold is positioned so that its axis is vertical, and during molding, resin is injected through gate g and filled from side A. The amount of resin injected increases, and when it reaches the second part of the web, the resin flows through the second part of the web at a uniform speed in the entire circumferential direction, making it possible to integrally mold a highly accurate gear.

If a gate is provided at the end of the A-side bearing boss, the value of the chamfer Ca cannot be increased, and torque loss increases. Furthermore, if there are sink marks or burrs caused by the gate on the abutment surface in the thrust direction, there is a risk that the gear will not rotate smoothly.

[0011] The numerical values shown in this example are just one example and do not limit the present invention. Either G1 or G2 may be a spur gear. Further, in this embodiment, the pitch circle radius of the gear G1 is larger than that of the gear G2, but the opposite may be possible. In short, any gear can be used as long as a force acts on the entire gear in the thrust direction and the reaction force of the thrust force is received on the A side.

0012

[Other Examples]

“Embodiment 2” FIG. 3 shows a second embodiment of the present invention.
The plan view of is the same as FIG. In the same figure, the explanation of the symbols is the same as in FIGS. 1 and 2, so the explanation will be omitted. This embodiment uses a so-called idler gear, and any type of helical gear may be used. Even if it is an idler gear, the thrust force FX1 generated between the driving side gear that meshes with the idler gear and the thrust force F of the driven side that meshes with the idler gear.
With X2, the thrust force on the driven side FX2 is reduced due to torque loss due to tooth surface friction, torque loss due to shaft friction, etc.
becomes larger. Therefore, the thrust force acting on the entire gear becomes FX2-FX1>0, and as a result, the idler gear receives the thrust force on the A side, resulting in a torque loss. Therefore, by making the surface A smaller as in this embodiment, the friction torque loss can be reduced.

The other explanations are the same as in the first embodiment. In addition, the difference in chamfer amount makes it foolproof, making it difficult to misdirect the idler gear during assembly, and preventing sink marks and burrs caused by the gate from coming into contact with the thrust surface and causing the gear to rotate smoothly.

Embodiment 3 FIG. 4 shows a third embodiment of the present invention, and the plan view of FIG. 4 is the same as FIG. 2. The only difference from Example 1 is that seven steps are provided instead of the chamfer Ca. The same can be done for idler gears.

``Example 4'' The drive devices using the molded gears shown in Examples 1, 2, and 3 have good gear accuracy and low torque loss regardless of the drive device, but one of the drive devices As an example, a driving device for an image forming apparatus will be described with reference to FIGS. 5, 6, and 7.

FIGS. 5 and 6 are a plan view and a side sectional view of the drive device of this image forming apparatus. In the same figure, gear G0
1 is integrated with the rotating body of motor M, module 0.5, helix angle 18°, helix angle direction is left, number of teeth is 29.
It is. Gear G02 meshes with gear G01 and has 76 teeth, and the meshing width between gear G01 and gear G02 is 10.2 mm. ) is 2. Gear G03 is a gear integrated with gear G02, has a module of 0.5, a helix angle of 18°, a helix angle direction to the right, and has 23 teeth. The gear G04 meshes with the gear G03 and has 87 teeth, and the meshing face width between the gear G03 and the gear G04 is 10.2 mm, and the meshing ratio is 2. Gear G05 is an integrated gear with gear G04 and is a gear of module 0.
6. The helix angle is 24.888°, the helix angle direction is to the left, and the number of teeth is 19. The gear G06 meshes with the gear G05 and has 67 teeth, the meshing tooth width between the gear G05 and the gear 06 is 9 mm, and the meshing ratio is 2. Gear G0
6 meshes with a drum gear GC1 integrated with the photosensitive drum of the process cartridge C shown in FIG. 7 to drive the photosensitive drum. The meshing tooth width in this part is also 9 mm, and the meshing ratio is 2. The drum gear GC1 has 4 teeth.
It is 6. This process cartridge C is detachable from the main body of the image forming apparatus, and houses therein a photosensitive drum, a primary charger, a developing device, and a cleaning device arranged around the photosensitive drum (described later).

The gear G07 meshes with the gear G03 and has 77 teeth, the meshing width between the gear G03 and the gear G07 is 10.2 mm, and the meshing ratio is 2. Gear G08 is a gear that meshes with gear G07, and has 58 teeth. The meshing tooth width between gear G07 and gear G08 is 10.2 mm, and the meshing ratio is 2. Gear G
09 is a spur gear integrated with gear G08, module 0.6
, the number of teeth is 19. Gear G10 meshes with gear G09 and has 29 teeth. The gear G11 meshes with the gear G10, and has 25 teeth and a shift amount of 0.12. The gear G12 meshes with the gear G11 and is also integrated with the fixing roller 46, and has 46 teeth and a displacement of -0.12.
It is. Moreover, all the gears shown in Examples 1 to 3 are used for gears G02 to G09. That is, the A side of the end face of the boss of each gear receives the thrust of the gear.

The gears G02 to G09 are rotatably passed through a central shaft, and the central shaft is respectively caulked to a U-shaped sheet metal 6 when viewed from the direction of arrow A in FIG. 6, thereby forming a drive unit. Note that the cross section in FIG. 6 is a cross section of the sheet metal 6. Gear G1
0 is rotatably attached to a fixed shaft 9 that is integrated with a rotating lever 12 shown in FIG. The lever 12 is interlocked with the opening/closing operation of the opening/closing structure 52 that opens and closes around the rotation center 51 shown in FIG.
Engages and disengages with 9. As shown in FIG. 5, the metal plate 6 and the motor M sandwich the main body side plate 3 and are also tightened with machine screws 4, and the plate metal 6 is also fixed to the main body side plate 3 with machine screws 5. The gear G11 is rotatably attached to a fixed shaft fixed to the fixing unit E shown in FIG. 8, and meshes with the gear G12 fixed to the fixing roller 46 of the fixing unit E.

FIG. 7 is an explanatory diagram showing how the gears mesh when the process cartridge C is inserted into the apparatus main body. In the figure, the gear GC2 is a sleeve gear that is integrated with the developing sleeve, and the drum gear It meshes with GC2 and drives the developing sleeve. The meshing tooth width in this part is also 9 mm, and the meshing ratio is 2. Note that the sleeve gear GC2 has 24 teeth. In this embodiment, the only gears included in the process cartridge C are GC1 and GC2, but if there are other gears, such as the primary charging roller, transfer roller, cleaning device, etc., the meshing ratio of those gears may be It is better to use an integer. However, among the rotating bodies in the process cartridge C, the ones with heavy torque are the photosensitive drum and the developing sleeve, so the engagement ratio of only the portions that drive these rotating bodies is an integer. Also good. Of course, this also applies to a drive system in which the developing sleeve is driven by a gear other than the drum gear.

FIG. 8 is a longitudinal sectional view showing the internal structure of a laser beam printer (image forming apparatus) 31A using transfer type electrophotography as an embodiment of an image forming apparatus using the above drive system.

In this embodiment, negative toner, image exposure, and reversal development are performed. A video signal sent from a controller (not shown) is input to the laser scanning optical system unit 28. This unit consists of a semiconductor laser, a collimator lens, a polygon mirror, an f-theta lens, a tilt correction lens, etc. Then, the video signal is applied to the semiconductor laser, and the diverging laser light is made into parallel light by a collimator lens, and is irradiated onto a polygon mirror rotating at high speed.
0 exposure section 31 is scanned. At this time, the timing at which the semiconductor laser scans the photosensitive surface of the photosensitive drum 30, that is,
In order to detect the timing of transmitting the video signal, a beam detector (not shown) that detects the laser beam is placed at a predetermined position before the laser beam scans the photosensitive surface of the photosensitive drum 30, and is synchronized with the generated BD signal. and send the video signal.

A charging roller 33, an exposure section 31, a developing device 34, a transfer roller 35, and a cleaning device 36 are provided around the photosensitive drum 30 in this order along the direction of rotation indicated by the arrow in the figure. The process cartridge C includes a photosensitive drum 30, a charging roller 33, a developing device 34, a cleaning device 36, and toner, and is detachable from the apparatus main body 31A.

-700 as the primary high voltage to the charging roller 33
V is applied to form a dark potential (VD) on the photoreceptor drum 30. An electrostatic latent image is formed on the exposed surface of the photosensitive drum 30 by a laser scanning optical system unit (not shown), and a negative toner is reversely developed by the developing device 34 .

The transfer material P loaded in the cassette 37 is fed by a paper feed roller 38 in response to a signal from a CPU (not shown). When the paper feed roller 38 is rotationally driven, the topmost sheet of the transfer material P loaded in the cassette 37 is separated from the next transfer material by the feeding force of the paper feed roller 38 and the separating action of the separation claw 39. P, and is fed from the cassette 37 to the right (in the figure), passes through conveyance guides 40a, 40b, and is transported to intermediate conveyance rollers 41a, 4.
I am led to 1b.

Furthermore, the transfer material P is attached to guide plates 42a and 42b.
, and enters into contact with the metallic upper resist roller 43a and the rubber-coated lower resist roller 43b. At this time, the upper registration roller 43a, the lower registration roller 4
3b is in a stopped state, and the conveyed transfer material P is moved between the intermediate conveyance rollers 41a, 41b and the registration upper roller 43a.
, and forms an appropriate loop with the lower registration roller 43b.

Next, the lower registration roller 43b is driven by a signal from the CPU, drives the upper registration roller 43a, and conveys the transfer material P. Next, the transfer material P is guided to an upper transfer guide 44a and a lower transfer guide 44b.

The transfer material P conveyed by the registration rollers 43a and 43b has the toner image formed on the photoreceptor drum 30 transferred by the transfer roller 35, passes through the conveyance guide 45, and is further transferred to the toner image by the fixing unit E. is fixed, intermediate paper ejection rollers 47a, 47b, paper ejection roller 4
The paper is discharged to the paper discharge tray 49 via 8a and 48b with the screen facing down.

The present invention is not limited to image exposure and reversal development systems, but also includes background exposure, regular development systems,
It goes without saying that similar effects can be obtained in image forming apparatuses using image exposure, regular development systems, and the like.

Furthermore, as an embodiment, it can be used in the drive system of any image forming apparatus, regardless of the type of image forming apparatus, such as electrophotographic type, inkjet type, thermal transfer type, etc. It is possible to obtain high-quality images with little loss.

[0030]

Effects of the Invention As explained above, in synthetic resin molded gears including helical gears, (1) the bearing boss end face A on the side receiving the reaction force of thrust load;
The cylindrical radius of is smaller than the cylindrical radius of the bearing boss end face B on the side that does not receive the reaction force of the thrust load, and a gate is provided on the bearing boss end face B on the side that does not receive the reaction force of the thrust load. As a result, a gear with good precision and low torque loss can be realized. (2) The outer diameter of the bearing boss including the bearing boss end surface A and the bearing boss end surface B is approximately equal, and the amount of chamfering of the bearing boss end surface A is larger than the amount of chamfering of the bearing boss end surface B. Furthermore, a gear with good precision and strength can be realized. (3) In addition, by using such a molded gear in an image forming device, torque loss due to sliding friction resistance of the boss end face of the gear that is used in large numbers is reduced, smooth rotation is obtained, and high-quality images are obtained. be able to.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a first embodiment of a molded gear including one or more helical gears according to the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a sectional view of a second embodiment.

FIG. 4 is a sectional view of a third embodiment.

FIG. 5 is a plan view of one embodiment of a driving device of an actual image forming apparatus.

FIG. 6 is a front view of FIG. 5;

FIG. 7 is a front view showing how gears mesh when the process cartridge C is inserted into the apparatus main body.

[Fig. 8] 1 of an image forming apparatus using the drive device shown in Figs. 5 and 6.
1 is a vertical cross-sectional view showing the internal configuration of a laser beam printer (image forming apparatus) using transfer type electrophotography as an example.

[Explanation of symbols]

Ca, Cb Chamfering φD　Outer diameter φDa, φDb Diameter

Claims (4)

[Claims] Claim 1: The diameter of the circle of the bearing boss end face (A) on the side receiving the reaction force of the thrust load is smaller than the diameter of the circle of the bearing boss end face (B) on the side not receiving the reaction force of the thrust load, A synthetic resin molded gear including one or more helical gears, characterized in that a synthetic resin injection gate is provided on the end face (B) of the bearing boss on the side that does not receive the reaction force of the thrust load. Claim 2: The bearing boss end face (A) on the side that receives the reaction force of the thrust load and the bearing boss end face (B) on the side that does not receive the reaction force of the thrust load are approximately equal in outer diameter, and 2. The chamfering amount of the bearing boss end face (A) on the side receiving the reaction force is larger than the chamfering amount of the bearing boss end face (B) on the side not receiving the reaction force of the thrust load. A synthetic resin molded gear containing one or more helical gears. 3. In a drive device equipped with a helical gear that slides and receives the reaction force of the thrust load of the gear on the end face of the bearing boss, the helical gear is attached to the bearing on the side that receives the reaction force of the thrust load. The diameter of the circle on the boss end face (A) is smaller than the diameter of the circle on the bearing boss end face (B) on the side that does not receive the reaction force of the thrust load, and the bearing boss on the side that does not receive the reaction force of the thrust load. A drive device characterized in that it is manufactured by providing a synthetic resin injection gate on the end face (B). 4. An exposure device that exposes the photoreceptor drum, a device that performs an image forming process such as a primary charger including the photoreceptor, a developing device, and a cleaning device, and an image forming apparatus for the image formed on the photoreceptor in the transfer section. The device includes a paper feeding device that feeds the transfer material, a transfer device, a conveying section that sends the transferred transfer material to the fixing device, and a fixing device, and the rotating body of the device is driven by a motor via a gear train. The image forming apparatus is provided with a helical gear that slides and receives the reaction force of the thrust of the gear on the end face of the bearing boss, and the helical gear is attached to the end face of the bearing boss on the side receiving the reaction force of the thrust load. The diameter of the circle in (A) is smaller than the diameter of the circle in the bearing boss end face (B) on the side that does not receive the reaction force of the thrust load, and the diameter of the circle on the side that does not receive the reaction force of the thrust load ( B) An image forming apparatus manufactured by providing a synthetic resin injection gate thereon.