JPH07293565A - Slide bearing device - Google Patents

Abstract

PURPOSE:To provide the slide bearing device which can maintain smooth rotation even in an environment in use where there exists great fluctuation in surrounding temperature. CONSTITUTION:The bearing device A is so constituted that it is made up of a bearing member 3 made of synthetic resin the inner circumferential surface 7 of which is a slide surface, a shaft member 1 made of synthetic resin the outer circumferential surface 4 of which is a slide surface, and of a sleeve 2 made of a copper alloy interposed between the aforesaid bearing member and the aforesaid shaft member where both the inner circumferential surface 5 and the outer circumferential surface of the sleeve are also slide surfaces, the sleeve 2 is fixed onto the shaft member 1 at the time of high temperature, and the sleeve 2 is fixed onto the bearing member 3 so as to be rotated at the time of low temperature.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a plain bearing device.
More specifically, the present invention relates to a sliding bearing device used in a use environment where there is a large temperature difference, such as an engine control device for a construction machine, especially a power shovel.

[0002]

2. Description of the Related Art In general plain bearing devices, the bearing side is made of a soft material rather than the shaft member so that "galling" does not occur, or the bearing side is made of a relatively soft material such as copper alloy. Bush made of material is often fixed by cold fitting. However, when the temperature difference in the operating environment is large, the gap between the shaft and the bearing or the bush becomes small at low temperature or high temperature, which may cause galling.

Therefore, conventionally, in the case of low precision, the clearance between the shaft and the bearing is set large in advance.
When a small clearance or high bearing accuracy is required, the material of the shaft and the bearing has the same or similar coefficient of thermal expansion, and is designed to keep the gap almost constant. Further, it has been proposed that the shaft side having a different coefficient of thermal expansion and the bush are firmly coupled by casting or the like to obtain an intermediate coefficient of thermal expansion to reduce the gap with the bearing (Japanese Patent Laid-Open No. 48-99539). (See the official gazette). Also, regarding the support structure for fixing the outer ring of the rolling bearing, various mechanisms have been proposed for suppressing axial displacement and radial backlash due to thermal expansion (Japanese Patent Laid-Open No. 4-496).
No. 8-99539, Japanese Utility Model Laid-Open No. 2-146213, Japanese Utility Model Laid-Open No. 2-146214, etc.).

[0004]

Among the above-mentioned conventional methods, the method of preliminarily increasing the clearance is intended to prevent galling at high temperatures, that is, the coefficient of thermal expansion of the shaft is If it is larger than that, the clearance at low temperature becomes extremely large, and conversely, if trying to solve the problem at low temperature, the clearance at high temperature becomes large, and in either case, the bearing accuracy becomes poor. Even when the coefficients of thermal expansion of the shaft and the bearing are made approximately the same, the coefficient of thermal expansion may not be isotropic due to the characteristics of the materials of the constituent elements. For example, in the case of shafts and bearings made of synthetic resin, isotropy cannot be obtained due to the problem of molecular orientation. Furthermore, since a radial load is applied to the bearing, the bearing may locally generate heat so that the bearing is not isotropic and the gaps are not uniform.

SUMMARY OF THE INVENTION It is a technical object of the present invention to make the clearance as uniform as possible in the sliding bearing in the case where the temperature difference in the use environment is large and to prevent the occurrence of backlash and galling regardless of the ambient temperature. It is a thing.

[0006]

A bearing device according to the present invention includes a bearing member having an inner peripheral surface that is a cylindrical rotary sliding surface, and a bearing member disposed on the inner periphery of the bearing member. A sleeve having both cylindrical rotating sliding surfaces, and a shaft member having an outer peripheral surface having a cylindrical rotating sliding surface. The sleeve is characterized by being made of a material having a high thermal conductivity and a thermal expansion coefficient lower than those of the shaft member and the bearing body.

In such a bearing device, it is preferable that the coefficient of thermal expansion of the bearing member and the shaft member are substantially equal to the difference between the coefficient of thermal expansion of the sleeve and the coefficient of thermal expansion of the sleeve. It is preferably made of synthetic resin and the sleeve is made of metal such as copper alloy. Further, it can be suitably adopted also in the case where each of the rotary sliding surfaces has a diameter three times or more larger than the axial length thereof. Further, in such a bearing device, in addition to the normal use method in which the bearing member is fixed and the shaft member side is rotated, a reverse use method in which the shaft member side is fixed and the bearing member side is rotated is also used. Alternatively, both the shaft member and the bearing member may be concentrically rotatable.

[0008]

When the temperature is high, the shaft member and the bearing member are thermally expanded, but the sleeve is less thermally expanded than those. Therefore, the sleeve is fixed to the surface of the shaft member, and there is a gap between the sleeve and the bearing member. The sleeve then expands somewhat due to the thermal expansion of the shaft member, so that the gap between the sleeve and the bearing member is not very large. In this state, the bearing member and the sleeve rotate while sliding between the outer peripheral surface of the sleeve and the inner peripheral surface of the bearing member. On the contrary, when the temperature is low, the sleeve is fixed to the bearing member side and slides between the inner peripheral surface of the sleeve and the outer peripheral surface of the shaft member. Even in this state, there are few gaps.

In the plain bearing device of the present invention, it is preferable that the coefficient of thermal expansion of the bearing member and the shaft member is substantially equal to the difference between the coefficient of thermal expansion of the sleeve and the coefficient of thermal expansion of the sleeve. The change in the gap is reduced.
Further, when the bearing member and the shaft member are made of synthetic resin and the sleeve is made of metal, particularly copper alloy such as brass, the galling prevention effect is great. Further, the sliding bearing device of the present invention has a small gap, so that the inclination of the shaft center is particularly suppressed when the diameter of the sliding surface is three times or more as large as the axial length. Great effect.

[0010]

Embodiments of the sliding bearing device of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the apparatus of the present invention, FIGS. 2 and 3 are enlarged sectional views of essential parts showing the states of the apparatus of FIG. 1 at high temperature and low temperature, respectively, and FIG. 4 is the apparatus of the present invention. FIG. 5 is a graph showing the relationship between the temperature change and the clearance change in FIG. 5, and FIG.

A plain bearing device A shown in FIG. 1 includes a disk-shaped shaft member 1 which rotates around an axis S, and a ring-shaped bush or sleeve 2 which is rotatably provided on the outer periphery of the shaft member 1. , A cup-shaped or ring-shaped bearing member 3 rotatably provided on the outer circumference of the sleeve 2. The term "rotatable" as used herein means that it becomes rotatable when a predetermined temperature condition is reached, as described later. In this embodiment, the bearing member 3 is fixed and the shaft member 1 side is rotatable, but it may be reversed, or both may be rotated around the common axis S.

The outer peripheral surface 4 of the shaft member 1 and the sleeve 2
The inner peripheral surface 5 of each is a cylindrical rotary sliding surface (hereinafter, simply referred to as a sliding surface). The outer peripheral surface 6 of the sleeve 2 and the inner peripheral surface 7 of the bearing member 3 are also cylindrical sliding surfaces. A step portion 8 is provided on the left side of the shaft member 1 in the drawing, and a step portion 9 is also provided on the right side of the bearing member 3.

The shaft member 1 and the bearing member 3 are made of a high-strength engineering plastic such as polyacetal, polycarbonate or polyamide. The thermal expansion coefficients α1 and α2 are usually about 4 to 6 × 10 ⁻⁵ / ° C. When a lubricating oil is used, those synthetic resin materials having oil resistance are preferable, and particularly when used at high temperature, those having heat resistance are preferable. On the other hand, the sleeve 2 has a high thermal conductivity of a copper alloy such as brass or an aluminum alloy (22 to 71 kcal / mh ° C.) and a thermal expansion coefficient of about 16 to 20 × 10 ^−6. The bearing member 3 is made of a metal smaller than the synthetic resin. Further, the clearance C1 between the shaft member 1 and the sleeve 2 is +0.
The clearance C2 between the sleeve 2 and the bearing member 3 is +0.1 to 0.2 with respect to the diameter D2 of the sleeve at room temperature.
It is a slip fit at about%.

Therefore, the device A of FIG. 1 slides between the shaft member 1 and the sleeve 2 or the sleeve 2 at normal temperature.
Whether it slides between the bearing member 3 and the bearing member 3 depends on conditions such as the coefficient of friction, the state of lubrication, and the magnitude of the tangential force applied to the sliding surface, in addition to the temperature. This state is the neutral area indicated by the symbol N in FIG. The horizontal axis of FIG. 4 represents the temperature and the vertical axis represents the displacement due to the temperature. The diagonal lines P1 and P2
And P3 schematically show changes of the shaft member 1, the sleeve 2, and the bearing member 3 based on the temperature.

Next, the bearing device A constructed as described above.
When the ambient temperature of 100 ° C. rises to about 100 ° C., the diameters of the shaft member 1 and the bearing member 3 having a high coefficient of thermal expansion increase considerably, as shown on the right side of FIG. Therefore, the clearance C2 between the bearing member 3 and the sleeve 2 increases, but the clearance C1 between the sleeve 2 and the shaft member 1 exceeds zero and becomes negative, so to speak, tight fit is achieved. This is the high temperature region indicated by the symbol H in FIG. Therefore, as shown in FIG. 2, the sleeve 2 has a shaft member 1
And the outer peripheral surface of the sleeve 2 and the bearing member 3 rotate relative to each other. In this state, when the absolute value of the clearance C1 between the shaft member 1 and the sleeve 2 increases, the sleeve 2 is stretched to some extent and the diameter increases. Therefore, the clearance C2 does not increase linearly and has a smaller value.

Next, when the environmental temperature drops to about -20 to 40 ° C., that is, in the low temperature region indicated by the reference symbol L on the left side in FIG. 4, the shaft member 1 and the bearing member 3 contract on the contrary,
The sleeve 2 does not shrink so much. Therefore, as shown in FIG. 3, the sleeve 2 is fixed to the bearing member 3 with a negative clearance C2, and the clearance C1 between the shaft member 1 and the sleeve 2 increases. Therefore, the shaft member 1 rotates relative to the sleeve 2. In the apparatus of FIG. 1, a gap C3 is provided between the sleeve 2 and the stepped portion 8 of the shaft member 1 so that the end surface of the sleeve 2 is not strongly pinched by the stepped portions 8 and 9 on both sides when the environmental temperature decreases. I have to.

Next, an actual application example of the plain bearing device of the present invention will be described with reference to FIG. FIG. 5 shows an actuator B used for electrically and remotely controlling the engine output of a construction machine such as a power shovel. In FIG. 5, reference numeral 11 is a base, and an L-shaped bracket 12 is attached to the base 11. The bracket 12 has a flange 13 together with a synthetic resin housing 14 and screws 1
The motor M is attached to the flange 13. The pinion 1 is attached to the shaft 16 of the motor M.
7, the planetary gear 19 and the ring gear 18 fixed to the inner surface of the hollow portion of the housing 14 on the left side in the drawing and the planetary gear 19 interposed between the pinion 17 and the ring gear 18, and the first reduction gear 20 of the planetary gear type. I am configuring. Planetary gear 1
9 is rotatably supported by a pin 21 on a carrier 22 serving as an output member.

In the space on the right side of the housing 14 in the drawing,
A cup-shaped first ring gear 25 and a cup-shaped second ring gear 26 are fixed so as to face each other. The number of teeth of the pair of ring gears 25 and 26 is somewhat different (for example, about three). Further, a first carrier 27 and a second carrier 28 are rotatably supported in the center holes of the ring gears 25 and 26, respectively, and both carriers 27 and 28 support a pin 30 for supporting a planet gear 29 and a fastening member. It is connected by the pin 31 of.

Both ends of the shaft of the sun gear 32 are supported in the center holes of the first and second carriers 27 and 28, and one end 33 of the shaft of the sun gear 32 is an output member of the first speed reducer 20. It is coupled so as to rotate together with the carrier 22. The sun gear 32, the planetary gear 29, the first and second ring gears 25 and 26, and the carriers 27 and 28 constitute a second Ferguson's paradox type speed reducer 34 having the second carrier 28 as an output member as a whole. There is.

A cup-shaped synthetic resin pulley housing 36 is provided on the right side of the housing 14, and the pulley housing 36 is fixed to the base by a cable pull-out portion 37. The inner peripheral surfaces 38, 39 of the open end of the housing 14 and the open end of the pulley housing 36 are
Are each a cylindrical sliding surface, and a ring-shaped first sleeve 40 made of a copper alloy having a rectangular cross section is fitted therein. The outer peripheral surface and the inner peripheral surface of the first sleeve 40 are rotational sliding surfaces.

On the other hand, the inner peripheral surface 41 of the opening at the right end of the pulley housing 34 is also a rotary sliding surface, and the second sleeve 42 made of a thin ring-shaped copper alloy is rotatably fitted to the inner peripheral surface 41. Has been done. Inside the pulley housing 36, a cylindrical protrusion 43 rotatably supported by the second sleeve 42 is provided at one end thereof, and a disc-shaped protrusion 44 rotatably supported by the first sleeve 40 is provided at the other end. A pulley 45 made of a synthetic resin for winding the cable is housed on the side surface of the shaft, and its central shaft 46 is connected to the second carrier 28 which is an output member of the second speed reducer 34.

The plain bearing device of the present invention is the pulley 45.
It is used in two places to support. That is, the inner peripheral surfaces 38 and 39 at the open ends of the housing 14 and the pulley housing 36 that serve as bearing members, the protruding portion 44 of the pulley 45 that serves as a shaft member, and the first sleeve 4 interposed therebetween.
0 constitutes the first plain bearing device A1. And an opening at the tip of the pulley housing 34 that serves as a bearing member,
A second plain bearing device A2 is composed of the cylindrical protrusion 43 of the pulley 44 that serves as a shaft member and the second sleeve 42 between them. Reference numeral P in FIG. 5 is a potentiometer fixed to a bracket 48 which is erected on the base 11, and a detection shaft 49 of the potentiometer P is fixedly connected to a pulley 45. An inner cable 51 of a control cable guided to the engine side is wound around the groove 50 on the outer periphery of the pulley 45, and one end of the inner cable 51 is locked to the pulley 45.

Actuator B constructed as described above
Is the same as the conventional one, and a drive current for forward rotation, stop, and reverse rotation is applied to the motor M from the outside, and the rotation speed is reduced by the first speed reducer 20 and the second speed reducer 34 accordingly. The driving force causes the pulley 45 to perform normal rotation, stoppage, and reverse rotation, and the inner cable 51 is wound on and fed out from the pulley 45 to control a fuel adjusting device such as a governor or throttle of the engine. In the first plain bearing device A1 and the second bearing device 2, the first sleeve 40 and the second sleeve 42 are fixed to the shaft member side or the bearing member side according to the temperature change of the external environment, as in the case of FIG. In this state, the shaft member is rotatably supported. Therefore, in both cases of high temperature and low temperature, the protrusion 44 which is the shaft member
And the clearance between the cylindrical protrusion 44 and the inner surfaces of the first sleeve 40 and the second sleeve 42, and the inner peripheral surfaces of the housing 14 and the pulley housing 36, which are bearing members, and the outer peripheral surfaces of the first and second sleeves 40 and 42. The clearances between them are properly maintained, and proper rotation can be maintained while preventing misalignment and galling.

[0024]

EFFECTS OF THE INVENTION The ambient temperature is 100 ° C. or −40.
Even at a low temperature of ℃, the clearance between the bearing member, the sleeve and the shaft member is appropriately maintained, and the sliding rotation is normally maintained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a plain bearing device of the present invention.

FIG. 2 is an enlarged cross-sectional view of essential parts showing a state of the apparatus of FIG. 1 at a high temperature.

FIG. 3 is an enlarged cross-sectional view of an essential part showing a state of the apparatus of FIG. 1 at a low temperature.

FIG. 4 is a graph showing the relationship between temperature changes and clearance changes in the device of the present invention.

FIG. 5 is a sectional view showing an embodiment of an actuator equipped with the device of the present invention.

[Description of Reference Signs] 1 shaft member 2 sleeve 3 bearing member A sliding bearing device B actuator 20 first speed reducer 34 second speed reducer 38 inner peripheral surface 39 inner peripheral surface 40 first sleeve 42 second sleeve 43 cylindrical protrusion 44 Protruding portion 45 Pulley A1 First sliding bearing device A2 Second sliding bearing device

Claims (8)

[Claims] 1. A bearing member, the inner peripheral surface of which is a cylindrical rotary sliding surface, and a rotary roller which is disposed on the inner periphery of the bearing member and has both an outer peripheral surface and an inner peripheral surface. The sleeve that is the moving surface and the inner circumference of the sleeve,
A sliding member made of a shaft member having an outer peripheral surface which is a cylindrical rotary sliding surface, the sleeve having a high thermal conductivity and a thermal expansion coefficient lower than those of the shaft member and the bearing member. Bearing device. 2. The apparatus of claim 1, wherein the coefficient of thermal expansion of the bearing member and the shaft member are approximately equal to each other as compared to the difference in coefficient of thermal expansion of the sleeve. 3. The device according to claim 2, wherein the bearing member and the shaft member are made of synthetic resin, and the sleeve is made of metal. 4. The sleeve is made of a copper alloy.
The described device. 5. The device according to claim 1, wherein each of the rotary sliding surfaces has a diameter three times or more larger than the axial length thereof. 6. The apparatus according to claim 1, wherein the bearing member is fixed and the shaft member is rotatable. 7. The apparatus according to claim 1, wherein the shaft member is fixed and the bearing member is rotatable. 8. The apparatus of claim 1, wherein both the shaft member and the bearing member are each rotatable.