JPH0372860B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cam gear that meshes with a roller gear, and in particular, a cam gear whose tooth profile (roller center locus) is formed by a trochoid curve. The present invention relates to a cam gear for a roller gear mechanism.

(Prior art) In a roller gear mechanism in which one of a gear pair is a roller gear and the other is a cam gear, it is known that when considering a perfect contact tooth profile based on tooth profile theory, the center locus of the roller in the cam gear depicts a cycloid. ing. Therefore, in the past, the cam gear of such a roller gear mechanism generally had a cycloidal roller center locus tooth profile.

However, when a roller gear is meshed with a cam gear having such a cycloidal tooth profile, approximately half the circumference of the roller contacts at the tooth base of the cam gear at the same time, making it susceptible to machining errors and resulting in smooth movement. There is a problem in that communication is no longer possible. Additionally, in order to avoid this, if the diameter of the roller is made smaller than the diameter of the root of the cam gear, or if the distance between the centers of the roller gear and the cam gear is increased, bumps may occur and the pressure angle may increase. This may cause excessive force to be applied to the contact area.

For this reason, it has been considered to make the roller center locus tooth profile of the cam gear a trochoid curve (for example, see Japanese Patent Laid-Open No. 57-25547). The roller center locus tooth profile of this cam gear is such that when the roller gear pitch circle, which is larger than the roller attachment pitch circle of the roller gear, rolls on the cam gear pitch circle, one point on the roller attachment pitch circle that is concentric with the roller gear pitch circle is It is said to be a trochoid curve.

(Problems to be Solved by the Invention) By the way, in such a roller gear mechanism, the roller of the roller gear is fitted with a roller pin in order to be supported rotatably. In this case, it is inevitable that a clearance will occur between the roller and the roller pin, or between the needle bearing located in between. Further, a clearance also occurs between the shaft of each gear and the bearing portion. Furthermore, there are machining errors in the tooth profile of the cam gear. Therefore, in order to absorb these clearances and machining errors, it is necessary to adjust the distance between the centers of both gears and apply a preload between the gears.

In that case, in a cam gear with a trochoidal tooth profile as described above, the pressure angle is different between the tooth root and the tooth tip, so the amount of normal preload is large on the roller that is in contact with the tooth root. , the amount of preload in the normal direction becomes small for the roller that is in contact with the tooth tip. However, for smooth motion transmission,
It is desirable that the rollers that are in contact at the tips of the teeth bear the load, while the rollers that are in contact with the roots of the teeth are free.

The present invention has been made in view of such problems, and its purpose is to provide a trochoidal curve for the roller center locus tooth profile of the cam gear.
When preload is applied between the roller gear and the cam gear while making sure that the shape of the tooth root is relaxed, the amount of preload on the roller that is in contact with the tooth tip of the cam gear is large, and the tooth root has a large amount of preload. By reducing the amount of preload on the rollers that are in contact with each other, it is possible to prevent excessive loads from being applied to the rollers and to ensure smooth transmission of torque.

(Means for Solving the Problems) In order to achieve this object, the present invention provides at least one of the theoretical pitch circles obtained by increasing the center-to-center distance between the roller gear and the cam gear to provide normal displacement. One of them is corrected according to the amount of clearance between the roller of the roller gear and the roller pin, and the tooth profile of the cam gear is determined by a trochoid curve drawn using the corrected pitch circle.

(Function) With this configuration, the tooth profile of the cam gear has a theoretical trochoid tooth profile determined using a theoretical pitch circle, so that the tooth thickness at the tooth tip portion is increased.
Therefore, when a roller gear is meshed with the cam gear and a preload is applied between both gears, the rollers of the roller gear will strongly contact the tips of the teeth of the cam gear.
There is weak contact at the root of the tooth.

Moreover, since the roller center locus tooth profile of the cam gear is a trochoid curve, the dedendum has a gentle curvature, and the contact area with the roller can be kept small.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

In the drawings, FIG. 1 is a schematic front view showing one embodiment of a roller gear mechanism using a cam gear according to the present invention, and FIG. 2 is an enlarged view of the main parts thereof.

As is clear from FIG. 1, this roller gear mechanism is constructed as a gear pair consisting of a roller gear 1 and a cam gear 2 circumscribing the roller gear. The roller gear 1 has a plurality of roller pins 4 provided at equal intervals on a roller mounting pitch circle 3, each of which has a roller 5 rotatably fitted and supported. The number of pieces is said to be 16. On the other hand, the cam gear 2 is a gear having a center located a predetermined distance away from the center of the roller gear 1 and has teeth number Zc, and includes teeth 7 that mesh with the roller 5 of the roller gear 1. In this example, the number of teeth on the cam gear 2
It is assumed that Zc=8. That is, this roller gear mechanism has a speed ratio Zc/Zr=0.5.

As shown in FIG. 2, there is a clearance of ε between the roller 5 of the roller gear 1 and the roller pin 4.

The roller center locus tooth profile of the cam gear 2 is a trochoid curve. The curve is defined as follows.

That is, as shown in FIG. 3A, consider a case where the roller mounting pitch circle 3 of the roller gear is equal to the meshing pitch circle of the gear.
At this time, the roller mounting pitch circle 3 circumscribes the meshing pitch circle 6 of the cam gear.
Let the distance between the centers at this time be a ₀ . At this time, the roller mounting pitch circle diameter of the roller gear is the number of teeth Zr
If the value divided by is defined as the module m, then a ₀ =m(Zr+Zc)/2=12·m. Next, as _shown in FIG. give. In this example,
Let Cy=0.5. Therefore, a=12.5·m. Then, the meshing pitch circle radius of the roller gear is
Rr and the meshing pitch circle radius Rc of the cam gear are respectively Rr=Zr/Zr+Zca=25/3m Rc=Zc/Zr+Zca=25/6m. Therefore, these meshing pitch circles are defined as the theoretical pitch circle 8 of the roller gear and the theoretical pitch circle 9 of the cam gear, respectively. If the roller gear is rolled while being in contact with the theoretical pitch circle 9 of the cam gear, using the theoretical pitch circle 8 of the roller gear as a rolling circle, a point on the roller attachment pitch circle 3 of the roller gear that is concentric with the rolling circle will be as shown in the figure. Draw the locus of the trochoid curve 10 as if This trochoid curve 10 will be referred to as a theoretical trochoid curve.

Next, each of the theoretical pitch circles 8 and 9 is corrected.
In the example of FIG. 3, the correction pitch circle 11 of the roller gear
The radius is set to be smaller than the radius Rr of the theoretical pitch circle 8 by the correction amount δ, and the corrected pitch circle 12 of the cam gear is made to have the same diameter as the theoretical pitch circle 9. The correction amount δ is equal to or slightly larger than the clearance amount ε between the roller 5 of the roller gear 1 and the roller pin 4,
That is, δ≧ε. Then, as shown in FIG. 3C, the corrected pitch circle 11 of the roller gear and the corrected pitch circle 12 of the cam gear thus corrected are circumscribed to each other, and the corrected pitch circle 11 of the roller gear is Roll it along the correction pitch circle 12 of the cam gear. At this time, one point on the roller attachment pitch circle 3 of the roller gear draws a locus of a trochoid curve 13 as shown by a solid line in the figure. This trochoid curve 13 will be referred to as a modified trochoid curve. This modified trochoid curve 13
is the theoretical trochoid curve 10 shown by the dotted line.
It will start up more quickly.

A circle 14 having the same diameter as the roller 5 of the roller gear 1 is moved along this modified trochoid curve 13, and its inner envelope 15 is defined as the tooth profile of the cam gear 2. Therefore, the tooth profile is modified trochoidal curve 1
It becomes a curve that maintains equal intervals with 3.

Next, when machining the adjacent teeth,
You can give the cam gear material an index of 1/Zc and process it in the same way.

The modified trochoid roller center locus tooth profile of the cam gear 2 formed in this way is, as shown by the solid line in FIG. ,
The tooth thickness at the tip of the tooth becomes large. Therefore,
A roller gear 1 meshed with the cam gear 2
The distance between the centers is greater than that of the roller gear that meshes with the cam gear of the theoretical tooth profile. As a result, when preload is applied between both gears 1 and 2, the roller 5 of the roller gear 1 makes strong contact with the tooth tip of the cam gear 2, but weakly contacts the tooth root with the roller pin 4. This results in play occurring between the two. In this way, motion is efficiently transmitted by the roller 5 that contacts the tooth tips of the cam gear 2. Furthermore, since the tooth profile of the cam gear 2 is formed by the modified trochoid curve 13 as described above, the roller 5 of the roller gear 1 and the teeth 7 of the cam gear 2 are maintained in a state of complete contact. Further, since the tooth shape of the root portion of the cam gear 2 has a gentle curvature, the contact area with the roller 5 is reduced, and motion transmission is not hindered by machining errors or the like. Furthermore, the root portion of the cam gear 2 has a tooth thickness greater than that of a cycloid tooth profile, resulting in a tooth profile with high load capacity.

By the way, in the cam gear 2 using such a trochoid curve, the pressure angle becomes 90 degrees at the moment the roller 5 of the roller gear 1 contacts the bottom of the tooth, so torque cannot be transmitted through the roller 5. . Therefore, it is necessary to ensure that the other roller 5 is in contact with the cam gear 2 at that moment. That is, at least two rollers 5 must always mesh with the cam gear 2. This condition is satisfied by setting the number of teeth Zr of the roller gear 1 and the number of teeth Zc of the cam gear 2 to values above the limit curve shown in FIG. 4.
This limit curve depends on the center locus increase coefficient Cy, the diameter of the roller 5, the outer diameter of the cam gear 2, etc., but tends to be a hyperbolic curve as shown in the figure. Therefore, in general, the simultaneous meshing ratio can be increased by increasing the number of teeth Zr and Zc. As in the above example, when the speed ratio Zc/Zr=0.5, if Zc=8, two or more rollers 5 are always
It can be seen that the cam gear 2 contacts the cam gear 2.

In the above embodiment, the radius of the correction pitch circle 11 of the roller gear is made smaller than the radius of the theoretical pitch circle 8 by the correction amount δ, and the correction pitch circle 12 of the cam gear is made to have the same diameter as the theoretical pitch circle 9. However, as shown in FIG. 5, the corrected pitch circle 11 of the roller gear remains the same as the theoretical pitch circle 8, and the corrected pitch circle 12 of the cam gear is changed by a correction amount δ from the radius of the theoretical pitch circle 9. As a large radius, the tooth profile of the cam gear 2 may be determined by the modified trochoid curve 13 formed when the corrected pitch circle 11 of the roller gear rolls on the corrected pitch circle 12 of the cam gear. good. In that case as well, a tooth profile substantially similar to that of the above embodiment can be obtained.

In addition, as shown in FIG. 6, the radius of the correction pitch circle 11 of the roller gear is set to the theoretical pitch circle 8.
The tooth profile of the cam gear 2 is determined by setting the radius of the corrected pitch circle 12 of the cam gear to be smaller than the radius of the theoretical pitch circle 9 by the corrected amount δ. You can also do this. In that case, the obtained modified trochoid curve 13 has a faster rise than the theoretical trochoid curve 10, so the tooth profile of the cam gear 2 determined by the modified trochoid curve 13 is The tooth thickness becomes even larger.

The present invention is applicable not only to the external roller gear mechanism as described above, but also to the internal roller gear mechanism and pinion gear mechanism.
It can also be applied to rack mechanisms.

(Effects of the Invention) As is clear from the above description, according to the present invention, the theoretical pitch circle when a positive dislocation is given by increasing the distance between the centers of the roller gear and the cam gear is Since the tooth profile of the cam gear is determined by the trochoid curve obtained by correcting the clearance between the roller and the roller pin and using the corrected pitch circle, it is possible to determine the tooth profile of the cam gear. Not only can the shape of the tooth base of the cam gear be made into a tooth profile that is relaxed while ensuring complete contact with the teeth of the cam gear, but when preload is applied between both gears, the cam The amount of preload on the roller that comes into contact with the tooth tips of the gear is large;
The amount of preload on the roller that comes into contact with the root of the tooth becomes smaller.
Therefore, it is possible to prevent an excessive load from being applied to the rollers, eliminate backlash, and provide a roller gear mechanism that can smoothly transmit torque.

[Brief explanation of drawings]

FIG. 1 is a schematic front view showing an embodiment of a roller gear mechanism using a cam gear according to the present invention, FIG. 2 is an enlarged view of the main parts of the roller gear mechanism, and FIGS. 3A, B, and C are , an explanatory diagram showing a method for determining the tooth profile of the cam gear; FIG. 4 is a graph showing the relationship between the number of teeth and the meshing ratio of the roller gear and the cam gear;
FIG. 5 is an explanatory diagram showing a different method for determining the tooth profile of a cam gear according to the present invention, and FIG. 6 is an explanatory diagram showing a further different method for determining the tooth profile of a cam gear according to the present invention. 1... Roller gear, 2... Cam gear, 3... Roller mounting pitch circle of roller gear, 4... Roller pin,
5...Roller, 6...Meshing pitch circle of cam gear without dislocation, 7...Teeth, 8...Theoretical pitch circle of roller gear, 9...Theoretical pitch circle of cam gear, 10...
Theoretical trochoid curve, 11... Correction pitch circle of roller gear, 12... Correction pitch circle of cam gear, 13...
Modified trochoid curve, δ...correction amount, ε...clearance amount.

Claims (1)

[Scope of Claims] 1. A roller comprising: a roller gear in which each roller is fitted to a plurality of roller pins provided at equal intervals on a roller mounting pitch circle; and a cam gear having a tooth profile that meshes with the roller gear. In a gear mechanism: Each pitch circle when the tooth profile of the cam gear gives a positive shift by increasing the center-to-center distance between the roller gear and the cam gear is the theoretical pitch of the roller gear and the cam gear, respectively. Assuming a corrected pitch circle of the roller gear and the cam gear, in which at least one of the theoretical pitch circles is corrected according to the amount of clearance between the roller and the roller pin of the roller gear,
When the corrected pitch circle of the roller gear is rolled while being in contact with the corrected pitch circle of the cam gear, it is formed as a curve that maintains an equal interval with a trochoid curve drawn by a point on the roller attachment pitch circle of the roller gear. Cam gear for roller gear mechanism. 2. The radius of the corrected pitch circle of the roller gear is smaller than the radius of the theoretical pitch circle of the roller gear by an amount equal to or slightly larger than the clearance amount, and the corrected pitch circle of the cam gear is The cam gear for a roller gear mechanism according to claim 1, wherein the tooth profile is determined by assuming that is equal to the theoretical pitch circle of the cam gear. 3. The corrected pitch circle of the roller gear is made equal to the theoretical pitch circle of the roller gear, and the corrected pitch circle of the cam gear is made such that its radius is
The roller gear mechanism according to claim 1, wherein the tooth profile is determined to be larger than the radius of the theoretical pitch circle of the cam gear by an amount equal to or slightly larger than the clearance amount. cam gear. 4. The radius of the corrected pitch circle of the roller gear is smaller than the radius of the theoretical pitch circle of the roller gear by an amount equal to or slightly larger than the clearance amount, and the corrected pitch circle of the cam gear is , whose radius is
The roller gear mechanism according to claim 1, wherein the tooth profile is determined to be larger than the radius of the theoretical pitch circle of the cam gear by an amount equal to or slightly larger than the clearance amount. cam gear.