JP2003172434A - Breather device for gear case - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a breather device for a gear case which prevents the blow-out of an oil mist to an air breather by separating the oil mist generated by the rotation of a gear internally mounted in a gear case (a differential case). <P>SOLUTION: A breather pipe 3 is erected on the upper face of the gear case (the differential case) 1 storing a lubricating oil 56, and an oil buffer 13 is continuously provided at the end of the breather pipe 3 and the air breather 26 is provided on the upstream side thereof. The oil buffer 13 contains a chamber (a first chamber) 53 for accommodating the oil mist and an air chamber (a second chamber) 54 located on the upstream side thereof in communication with the air breather 26 via a buffer plate 19. The buffer plate 19 has a gap 55 via which air separated from the oil mist flows into the air breather 26 and is provided adjacent the upper end of the oil buffer 13. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breather device for a gear case, for example, a breather device for a differential case, which incorporates a gear for transmitting power of a work vehicle or the like.

[0002]

2. Description of the Related Art Conventionally, as a breather device for a differential case of a work vehicle or the like, an internal space 101 of a differential case 100 as shown in FIG. 4 has an air breather 103 communicating with the outside through a breather pipe 102 and a breather pipe 102.
The structure provided on the upstream side is used.

That is, as shown in FIG. 4, a specified amount of lubricating oil (oil) 10 is supplied to the bottom of the differential case 100.
Reference numeral 4 lubricates the rotational friction portion by the rotation of the ring gear 105 or the like installed in the differential case 100. When the ring gear 105 and the like continuously rotate at high speed, the oil is agitated (splashed) in the internal space 101 of the differential case 100 by the ring gear 105 and the like, and is scattered in a splash state. These oils include mist-like oils and oils that do not result in mist-like oils (hereinafter, these oils are referred to as oil mist). A breather pipe 102 is provided in the differential case 100 to prevent the oil mist from being blown out from the air breather 103.
An air breather 103 that communicates with the atmosphere is provided on the upstream side of the breather pipe 102.

[0004]

However, since the ring gear 105 and the like continuously rotate at high speed,
When the oil mist travels along the inner wall surface (including the upper surface and the side surface) 106 of the differential case 100, or the vicinity of the inlet 102b of the breather pipe 102a inserted into the differential case 100 or the inside of the breather pipe 102a is blocked, the differential case 100 The internal space 101 may not communicate with the atmosphere. Therefore, as the temperature of the oil rises, the temperature of the internal air of the differential case 100 rises and expands. The expansion of the internal air becomes a force for pushing up the oil mist near the inlet 102b of the breather pipe or the inside of the breather pipe 102a, and the oil mist is ejected to the outside of the air breather 103.

In order to prevent the oil mist from being blown out from the air breather, the inlet 102b of the breather pipe inserted inside the differential case 100 is
As a means for reducing the rise of the oil mist due to the scattering of the oil mist away from the ring gear 105, the length of the breather pipe inserted inside the differential case 100 is shortened so that the breather pipe 102c is provided only on the upper part of the differential case 100. It is conceivable that the air breather 103, which is provided and communicates with the breather pipe 102c, is provided on the upstream side. However, even in the case of this structure, it is not possible to prevent the oil mist from spouting from the air breather to the outside.

By the way, as disclosed in, for example, Japanese Unexamined Patent Publication No. 5-26329, a reservoir tank is fixed to an upper part of a gear case, and an opening for allowing hydraulic oil in the gear case to flow into the reservoir tank is provided in this tank. Installed on the bottom of
There is known a structure in which a breather device that connects the inside of the tank to the atmosphere is connected to the upper end of the tank.

With this structure, the HST hydraulic transmission is operated by the hydraulic oil in the gear case, and it is necessary to secure a space for separately fixing the reservoir tank in the upper part of the gear case. Therefore, the shape of the gear case becomes large and the weight also increases. Furthermore, there is a possibility that an oil mist generated by stirring the operating oil (oil that also serves as lubricating oil) by the rotation of the gear installed in the gear case may be ejected from the reservoir tank to the outside of the breather device.

The present invention has been made in view of the above points, and a breather device for a gear case capable of separating oil mist generated by the rotation of a gear installed in a gear case and preventing the oil mist from being blown out to an air breather. The purpose is to provide.

[0009]

According to a first aspect of the present invention, there is provided a breather device in which an internal space of a gear case storing lubricating oil communicates with an air breather through a breather pipe. An oil buffer that prevents the oil mist generated inside the gear case from being blown out to the air breather is connected in series, and the air breather is provided on the upstream side of the oil buffer.

With this configuration, when a specified amount of oil is supplied to the bottom of the gear case containing the gear and the like and the gear and the like are rotated, the rotational friction portion is lubricated. When the rotation of the gear etc. is increased to continuously rotate at high speed, the oil stirs inside the gear case by the gear etc. and is scattered in a splash state to become an oil mist. These oil mists travel along the inner wall surface of the gear case. Further, if the vicinity of the inlet of the breather pipe or the inside of the breather pipe is blocked with oil mist, the internal space of the gear case will not communicate with the atmosphere. Therefore, as the temperature of the oil mist rises, the temperature of the air inside the gear case rises, and when it expands, it acts as a force that pushes up the oil mist blocked at the inlet of the breather pipe and the inside of the breather pipe, and the oil mist inside the breather pipe. Is sprayed into an oil buffer communicating with the breather pipe and separated by the oil buffer. The separated oil descends inside the breather pipe by gravity and returns to the inside of the gear case. Therefore, the ejection of oil mist to the air breather is prevented. Further, the air separated by the oil buffer is purified by an air breather communicating with the oil buffer, and is discharged to the outside as clean air.

After the oil mist is separated and returned to the inside of the gear case, the air inside the gear case does not expand because it communicates with the atmosphere. Therefore, the oil mist generated inside the gear case does not block the vicinity of the inlet of the breather pipe or the inside of the breather pipe.
However, if the high speed rotation is further continued, it may be blocked again. When it is blocked, the oil mist blows up again due to the expansion of the air inside the gear case, and this is repeated.

When the temperature of the oil mist rises to a certain temperature and the temperature difference from the outer surface temperature of the gear case stops changing, a so-called temperature heat balance (described later) occurs, and the oil mist blows up. repeat. After the heat balance occurs, the expansion of the air inside the gear case decreases, and the rise of oil mist also decreases.

Further, according to the invention of claim 1, the air breather is not contaminated by the oil mist, so that the frequency of cleaning the air breather or replacing the element is reduced, which is advantageous for maintenance. Since the oil buffer is provided outside the gear case, it is not necessary to increase the size of the gear case, and it can be easily retrofitted to a gear case equipped in an existing work vehicle or the like.

As described in claim 2, it is preferable that the oil buffer includes a chamber for accommodating the oil mist and an air chamber communicating with the air breather through a buffer plate on an upstream side thereof.

In this way, even if the oil mist generated inside the gear case blows up inside the breather pipe, it is blown up into the chamber containing the oil mist of the oil buffer communicating with the breather pipe, The separated air hits the buffer plate provided on the upstream side, and the separated air flows through the upstream air chamber and flows into the air breather. Since the air chamber is provided on the upstream side of the buffer plate, even if oil mist overflows from the buffer plate, it is blocked by the upstream chamber and does not flow into the air breather.

According to a third aspect of the present invention, the buffer plate has a gap for allowing the air separated from the oil mist to flow into the air breather, and is preferably provided close to the upper end of the oil buffer. .

In this way, the air separated from the oil mist flows into the air breather communicating with the oil buffer through the gap of the buffer plate. Further, since the buffer plate is provided close to the upper end of the oil buffer, the volume of the chamber that houses the oil mist is ensured to be larger than the volume of the upstream air chamber. The volume of the chamber that houses this oil mist is
The maximum amount of oil mist ejected when the temperature of the oil mist inside the gear case reaches the upper limit can be accommodated. Therefore, the oil mist is prevented from overflowing the chamber. The volume of the upstream air chamber is set so that the oil mist does not reach the inner upper surface of the air chamber even when the work vehicle or the like is steeply inclined. Therefore, it is necessary to ensure that the volume of the chamber that houses the oil mist is larger than the volume of the upstream air chamber.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view showing a breather device for a gear case according to the present invention, for example, a breather device for a differential case. FIG. 1 is a sectional view taken along the line I--I of FIG. 3, and FIG.
2B is a sectional view taken along the line III-III of FIG. 2A, and FIG. 3 is a schematic plan view of the differential case.

As shown in FIGS. 1 to 3, the breather device 2 of the differential case 1 according to the present invention has a breather pipe 3 standing on the upper surface of the differential case 1 which stores a prescribed amount of lubricating oil (oil) 56. A first nipple 6 is provided for installation.
The first nipple 6 includes a parallel screw portion 4 and a tapered screw portion 5.
Have. The upper surface of the differential case 1 is provided with a screw hole 7 that is screwed into the parallel screw portion 4. The O-ring 8 is attached to the parallel thread portion 4.
And the first nipple 6 is oil-tightly attached to the differential case 1 by screwing. The internal lower end portion of the breather pipe 3 is provided with a tapered screw hole 9 that is screwed into the tapered screw portion 5 of the first nipple 6, and the first nipple 6 and the lower end portion of the breather pipe 3 are screwed together to form the breather pipe. 3 is erected on the differential case 1. The first nipple 6 is provided with a through hole 12 that connects the internal space 10 of the differential case 1 and the internal portion 11 of the breather pipe 3.

Next, the oil buffer 13 connected to the tip of the breather pipe 3 has a cylindrical body portion 18.
A band-shaped buffer plate 19 is fixed to the inner surface 20 of the body portion 18 by welding on the upper portion of the body portion 18. Further, in order to surround the body portion 18, upper and lower end portions of the body portion 18 are respectively oil-tightly welded by circular welding of a circular upper plate 21 and a lower plate 22 having a diameter slightly larger than that of the body portion 18. It is configured by fixing.

Further, the second nipple 15 provided at the tip of the breather pipe 3 is provided with a tapered screw portion 14 and a flange portion 17, and a through hole 24 communicating with the inside 11 of the breather pipe 3 is formed in the central portion. Set up. The through hole 24 has the same diameter as the through hole 12 of the first nipple 6. Further, a through hole 25 communicating with the through hole 24 of the second nipple 15 is provided in the central portion of the lower plate 22 of the oil buffer 13. The through hole 25 has the same diameter as the through hole 24.

In order to connect the tip of the breather pipe 3 and the oil buffer 13 in series, the oil buffer 13
The flange portion 17 of the second nipple 15 is oil-tightly fixed to the outer surface portion 23 of the lower plate 22 by welding all around. The tapered screw portion 14 of the second nipple 15 is screwed into the tapered screw hole 16 of the breather pipe 3 to be continuously provided.

The breather pipe 3 described in this embodiment is
For example, outer diameter 22mm, inner diameter 14mm, length 200mm
It is a steel pipe.

Next, the structure of the air breather 26 provided on the upstream side of the oil buffer 13 will be described.

A tubular support member 27 is provided at the center of the air breather 26 to support the element 33, the cover 37, etc., and a taper-shaped screw portion 28 is formed at the lower end of the support member 27 to provide a central portion. In this case, a circular cylindrical hole 30 communicating with the inside 29 of the oil buffer 13 is bored except for the upper end 40. The diameter of this hole 30 is equal to that of the oil buffer 13.
Of the lower plate 22 having the same diameter as the through hole 25 provided in the central portion of the lower plate 22, and two long holes 42 communicating with the space (gap) 32 provided on the outer periphery of the support member 27 facing each other. There is.

A tapered screw hole 31 that is screwed into the tapered screw portion 28 at the lower end of the support member 27 is provided at the center of the upper plate 21 of the oil buffer 13. Support member 2
A gap 32 is provided on the outer circumference of the element 7 to form an element 33 (for example, filter paper) that is concentric with the support member 27, and the lower end portion of the element is provided with a flange portion 34 below the support member 27 via a packing 35. Lay in The flange portion 34 of the support member 27 is further provided with a cylindrical protrusion 4 in the vertical direction.
3 is integrally formed. A gap 36 is provided on the outer circumference of the element 33, and a cover 37 concentric with the support member 27 is provided.
And a step portion 38 capable of accommodating the upper end portion of the element 33 is integrally formed on the upper portion of the cover 37.
The cover 37 has a packing 39 on the upper end of the element 33.
To the upper end 40 of the support member 27 through the element 33
Tighten with the screw member 41 so as to surround the.

In order to provide the air breather 26 on the upstream side of the oil buffer 13, the taper-shaped screw portion 28 of the support member 27 is screwed into the taper-shaped screw hole 31 of the upper plate 21 of the oil buffer 13 so as to be continuously provided. To do.

With the above structure, the breather pipe 3 is erected on the upper surface of the differential case 1, the oil buffer 13 is connected to the tip of the breather pipe 3, and further,
An air breather 26 is provided on the upstream side.

The breather pipe 3 erected on the upper surface of the differential case 1 has a band 44 as a support member formed at an intermediate portion thereof, as shown in FIG. 1, to form a frame (not shown) of a work vehicle or the like. To support.

The position where the breather pipe 3 is attached to the differential case 1 (that is, the position of the mounting screw hole 7 (breather hole) for the first nipple 6 provided on the upper surface of the differential case 1) is the side view in this embodiment. 2 is near the rear wall 45 of the differential case 1 shown in FIG. 1, and near the ring gear 48 shown in FIG. 3 in a plan view. However, as described above, since the oil mist travels and scatters on the inner wall surface (top surface and side surface) 46 of the differential case 1, where the breather hole (screw hole 7) is provided on the upper surface of the differential case. However, there is not much difference in clogging due to oil mist.

Next, the outline of the gears and the like incorporated in the differential case 1 will be described with reference to FIG.

Inside the differential case 1, rotation from a drive shaft of a power transmission system of a work vehicle (not shown) is transmitted from the drive pinion 47 to the ring gear 48,
The drive shaft 51 for the left and right wheels (not shown) is converted to a right angle.
A pinion 49 that transmits power to the L and 51R, a side gear 50, and the like are installed.

Such a gear is incorporated in the differential case 1, and a prescribed amount of oil 56 is supplied to the bottom of the differential case 1. The specified amount of the oil 56 (the upper surface of the oil) varies depending on the magnitude of the stirring resistance of the oil by the gear or the like and the characteristics of the oil, but generally, the oil is supplied to a position slightly lower than the center of the shaft of the ring gear 48 or the like. . In the present embodiment, for example, 2 from the center of the axis of the ring gear 48 downward.
It is refueling up to a position that is lowered by 7 mm.

This specified amount of oil 56 is a lubricating oil for gears, which becomes an oil mist by continuous high speed rotation of the ring gear 48 and the like, and propagates through the inner wall surface 46 of the gear case 1. Further, when the oil mist blocks the vicinity of the breather hole (screw hole 7) provided on the upper surface of the differential case 1 which is a passage to the atmosphere, or the inside 11 of the breather pipe 3, etc., the internal space of the differential case 1 The air of 10 expands as the temperature of the oil mist rises. By this expansion, the oil mist flows in the inside 11 of the breather pipe in the direction from arrow A to B and is jetted up into the oil buffer 13, and the oil mist hits the buffer plate 19 and separates as shown by arrow C.

The separated oil descends inside the breather pipe 11 and returns to the inside of the differential case 1. The air separated by the buffer plate 19 flows out in the arrow D direction and flows into the circular tubular hole 30 of the air breather 26 in the arrow E direction. Further, the air that has flowed out of the elongated hole 42 in the F direction and passed through the element 33 to be purified is
7 The inside flows out as clean air from the arrow G direction to the outside H direction.

As a result, the air breather 26 is not contaminated with oil mist, so the frequency of cleaning the air breather 26 and replacing the element 33 is reduced, and maintenance is advantageous.

Now, the temperature rise of the oil mist generated inside the differential case 1 and the spouting state of the oil mist are measured by experiments, and will be considered next. (1) Temperature rise of oil mist When the outside air temperature is 25 ° C to 30 ° C, when the ring gear 48 and the like are continuously rotated at high speed for about 1 hour, the temperature of the oil mist is from room temperature to 70 ° C. The temperature rises to the range of 80 ° C to 80 ° C. The temperature of the oil mist does not rise even if the high speed rotation is continued. This is because the outer surface temperature of the differential case 1 temporarily rises as the temperature of the oil mist rises, but the outer surface of the differential case 1 is dissipated by the outside air. Therefore, the temperature difference between the internal temperature of the differential case 1 (the temperature of the oil mist) and the external surface temperature of the differential case 1 does not fluctuate about 1 hour after the operation is continued (the internal and external temperature differences fluctuate with the passage of time). Will not). So-called temperature heat balance occurs.

Therefore, the amount of oil mist blown up by the expansion of the internal air of the differential case 1 increases until the heat balance occurs. (2) State of spraying oil mist In the case of the prior art shown in FIG. 4, one open lower end of a vinyl tube having an inner diameter of 14 mm is inserted to the lower inside of the differential case 100 (102
The same as the lower end of a), and the other is extended in the vertical direction of the differential case 100. The upper end of the vinyl tube is not sealed and is open to the atmosphere. When heat balance occurs when the ring gear 105 and the like are continuously rotated at high speed, the oil mist blows up from the top surface of the differential case 100 by one.
190 mm was measured. In the case of the present invention shown in FIG. 1, one open end of a vinyl tube having an inner diameter of 14 mm is made the same as the inner wall surface 46 of the differential case 1, and the other is extended in the vertical direction of the differential case 1. The upper end of the vinyl tube is not sealed and opened to the atmosphere as in (1) above. Rotate the ring gear 48 etc. continuously at high speed,
At the time when heat balance occurred, the ejection of oil mist was measured at 590 mm from the upper surface of the differential case 1.

The oil mist is blown up by the rotation of the ring gear or the like, and the oil mist closes the inlet of the vinyl tube or the inside of the vinyl tube, the internal air of the differential case 1 is expanded, and the expansion is caused. It is a thing.

The measured value of 590 mm obtained above is
Compared to the above, it is reduced by about 50%. This is because the lower part of the vinyl tube was not inserted into the differential case, and the oil mist rising into the vinyl tube due to the scattering of the oil mist was reduced.

Next, inside the oil buffer 13, there is provided a first chamber 53 for accommodating the oil mist in the lower portion and a second chamber 54 located upstream from the buffer plate 19.

In this way, the oil mist blown up in the first chamber 53 hits the buffer plate 19 and is separated as shown by the arrow C. The separated air enters the second chamber 54 as shown by arrow D and flows into the air breather 26 in the direction of arrow E. Further, since the second chamber 54 is provided on the upstream side, even if the oil mist should overflow from the buffer plate 19, the oil mist hits the inner surface 52 of the upper plate 21 of the second chamber 54 and is separated, so that the oil mist is separated from the air breather. It does not flow into 26.

Further, as described above, the oil buffer 13
Is a simple structure and is effective for separating oil mist. Further, the buffer plate 19 abuts the inner surface 20 of the body portion 18 of the oil buffer 13 at both end edges in the longitudinal (diameter) direction, and the width ( It is a strip-shaped plate having a gap 55 on both sides in the (radius) direction. The width of this plate is
The gap 55 may be wider than the diameter of the through hole 25 formed in the central portion of the above, and the gap 55 may be a gap through which the air separated from the oil mist can flow out. Furthermore, the buffer plate 19
Close to the upper plate 21 of the oil buffer 13,
The inner surface 20 is fixed by welding.

In this way, the separated air flows out in the direction of arrow D through the gap 55 of the buffer plate 19.

Further, the buffer plate 19 is the upper plate 2
By approaching 1, the volume of the first chamber 53 becomes
Increase from the second chamber 54. The volume of the first chamber 53 is a volume capable of accommodating the maximum amount of oil mist, and the volume of the second chamber 54 is such that when the work vehicle or the like steeply tilts, the oil mist overflows from the gap 55. The volume does not reach the inner surface 52 of the upper plate 21. According to the present embodiment, when the work vehicle or the like inclines with respect to the ground by, for example, 30 °, the first volume of
The volume ratio of the chamber 53 is 60%, and the volume ratio of the second chamber 54 is 40%.

In addition to the above, the breather device for a gear case according to the present invention can be configured as follows. (1) The material of the breather pipe 3 is not limited to the steel pipe, and may be a pipe made of non-ferrous metal or resin. (2) The position of the breather hole (screw hole 7) provided on the upper surface of the differential case 1 may be provided on the side surface of the differential case 1. (3) The breather pipe 3 is the differential case 1 in this embodiment.
Although a straight pipe is erected vertically on the upper surface of the above, it may be a bent pipe. (4) The material of the oil buffer is not limited to a steel plate, and may be any material that can be surrounded in an oil-tight manner.

[0048]

The present invention is implemented as described above and has the following effects.

According to the first aspect of the invention, the oil buffer for preventing the oil mist from blowing into the air breather is connected to the tip of the breather pipe, and the air breather is provided on the upstream side of the oil buffer. It can be separated by a buffer. Therefore, the air breather is not contaminated with oil mist,
Maintenance is advantageous because the frequency of cleaning the air breather and replacing the element is reduced.

Further, since the oil buffer is provided outside the gear case, it is not necessary to enlarge the gear case, and it can be easily retrofitted to a gear case of an existing work vehicle or the like.

As described in claim 2, if the oil buffer is provided with a chamber for accommodating the oil mist and an air chamber communicating with the air breather via a buffer plate on the upstream side thereof, the oil mist can be provided. When it is blown up, it is blown up into the chamber containing the oil mist, but it hits the buffer plate to separate the oil mist, and the separated air flows through the air chamber on the upstream side and flows into the air breather. With this, the oil mist can be separated accurately. Even if the oil mist overflows from the buffer plate, it will not be blocked by the air chamber on the upstream side and will not flow into the air breather.

According to a third aspect of the present invention, the buffer plate has a gap for allowing the air separated from the oil mist to flow into the air breather, and is provided near the upper end of the oil buffer. The volume of the chamber that houses the oil mist can be ensured to be larger than the volume of the upstream air chamber.

The volume of the chamber for accommodating this oil mist is such that the maximum amount of oil mist ejected when the temperature of the oil mist inside the gear case reaches the upper limit,
Since it can be stored, the oil mist can be prevented from overflowing from the chamber. Also, the volume of the upstream air chamber is set so that the oil mist does not reach the upper surface inside the air chamber even when the work vehicle or the like is steeply inclined. Does not flow.

[Brief description of drawings]

1 is a side sectional view of a breather device for a gear case according to the present invention, for example, a breather device for a differential case, and is a sectional view taken along the line I-I in FIG.

2 (a) is a sectional view showing a breather device of the present invention, which is a sectional view taken along line II-II in FIG. 2B is a sectional view taken along the line III-III in FIG.

FIG. 3 is a schematic plan view of a differential case, in which gears and the like are schematically shown by a chain double-dashed line.

FIG. 4 is a view similar to FIG. 1 for a conventional example.

[Explanation of symbols]

1 differential case (gear case) 2 breather device 3 Breather Pipe 7 Screw hole (breather hole) 10 internal space 13 oil buffer 19 buffer plate 26 Air Breather 53 First chamber 54 Second Chamber 55 Gap 56 Lubricating oil

Claims (3)

[Claims] 1. A breather device in which an internal space of a gear case that stores lubricating oil communicates with an air breather through a breather pipe, wherein a tip of the breather pipe has an oil mist generated inside the gear case. A breather device for a gear case, characterized in that an oil buffer for preventing spouting to the air breather is connected in series, and the air breather is provided on the upstream side of the oil buffer. 2. The gear case according to claim 1, wherein the oil buffer includes a chamber that accommodates the oil mist and an air chamber that communicates with the air breather via a buffer plate on an upstream side thereof. Breather device. 3. The buffer plate has a gap for allowing the air separated from the oil mist to flow into the air breather, and is provided in the vicinity of the upper end of the oil buffer. Breather device for gear case.