JP4644012B2 - transmission - Google Patents

Description

  The present invention relates to a vehicle transmission, and more particularly to an oil leak prevention structure for an air breather in a gear transmission.

  A vehicle driven by an engine or the like includes a transmission to obtain speed and driving force according to road conditions. In a transmission, a plurality of transmission gears provided on an input shaft and an output shaft are selected and meshed to operate, and power is transmitted at a predetermined gear ratio. Then, in order to smooth the operation of the rotating part and suppress the deterioration of the function due to wear, it is generally performed that lubricating oil is enclosed in the case of the transmission, and is scraped up and lubricated by a rotating transmission gear. Further, when the transmission is operated, the temperature rises due to heat generated by friction. In order to avoid the internal pressure increase accompanying this, it is common to provide an air breather for breathing.

The air breather is usually provided in the upper part of the case in order to prevent leakage of the lubricating oil. However, the provision at the top is not sufficient to prevent leakage of lubricating oil that is scraped up and scattered. As a countermeasure, the applicant of the present application, for example, in Patent Document 1, discloses a gear transmission having a partition that partitions a case and a guide wall that blocks a part of the opening of the partition. The partition wall defines a communication chamber that communicates the inside and the outside of the case, narrows the opening through which air flows, and prevents the lubricating oil from directly splashing into the air breather. The guide wall further narrows the opening and forms an oil film to prevent leakage of the lubricating oil. Not only the guide wall of patent document 1, but the shielding board which blocks most of an opening part and prevents oil leakage is used abundantly.
JP 2001-65669 A

  Incidentally, conventional shielding plates and guide walls have been assembled by caulking, bolting, or the like. Therefore, the number of parts is large in spite of a simple structure, and it takes time to work with tools in a limited space. On the other hand, there was no case in which a gap was generated between the shielding plate and the partition wall, and some lubricating oil reached the air breather through the communication chamber.

The present invention has been made in view of the above-described background, and does not require assembly parts such as bolts, and there is no risk of the shielding plate falling off during assembly work that is simply fitted without using an assembly tool. Provided is a transmission having an oil leakage prevention structure capable of reliably preventing leakage of lubricating oil and having excellent overall economic efficiency including material costs and assembly work costs.

A transmission according to the present invention includes a case in which lubricating oil for lubricating a rotating portion is sealed, a transmission mechanism including a power transmission shaft and a transmission gear housed in the case, and an upper portion of the case. A communication chamber that communicates with the outside, an air breather that is provided between the communication chamber and the outside, and breathes in accordance with a change in the internal pressure of the case, and the transmission gear that is provided at the opening of the communication chamber is scraped up And a shielding plate for preventing leakage of lubricating oil, wherein the case has an arc-shaped groove along an inner wall surface defining the communication chamber, and the shielding plate is an arc-shaped outer arc portion. And is inserted from one end side of the arc-shaped groove and rotated and fitted.

  The present invention improves the shielding plate provided at the opening of the communication chamber and the assembly structure thereof.

  The case can be formed by a manufacturing method such as molding using a hard material such as metal. The enclosed lubricating oil stays in the lower part in the case. The power transmission shaft is, for example, an input shaft or an output shaft, and may have a counter shaft or other shafts depending on the structure of the transmission. These shafts can be rotatably held through the case wall and provided with a plurality of transmission gears. Also, the upper part of the case can be partitioned by a partition wall to form a communication chamber. Then, an air breather can be provided so as to penetrate a part of the case wall forming the upper side of the communication chamber and open to the outside. The air breather may be unidirectional to release an increase in internal pressure, or may be bidirectional to perform both intake and exhaust. Moreover, you may provide the strainer which collects mist-like lubricating oil, the filter which removes the dust in the air, etc. Further, the lubricating oil inlet may also be used, or may be provided separately.

  The communication chamber has an opening that opens into the internal space of the case where the speed change mechanism is disposed. A groove can be provided in the case wall or the inner wall surface of the partition wall forming the opening. Furthermore, a shielding plate fitted in the groove can be provided.

The arc-shaped groove preferably has a central angle exceeding 180 °. In order to realize this, it is preferable that the case wall or the partition wall forming the opening is a part of a cylinder having a central angle exceeding 180 °. And if the groove | channel of the circumferential direction is provided in the inner wall surface of an opening part, a groove | channel will become circular arc shape. The cross-sectional shape of the groove may be a rectangular groove, and there is no restriction.

  The shielding plate is preferably formed of a flexible material. The flexible material may be a nylon resin. The shielding plate is preferably formed by a manufacturing method such as molding using a material that can be bent, such as nylon resin. The shielding plate fitted in the arc-shaped groove may have a fan shape or an arc shape corresponding to the diameter of the groove bottom at the same central angle. Further, it can be appropriately cut out or bent according to restrictions such as irregularities and obstacles on the case side.

  When assembling a shielding plate made of a flexible material into the above-described arc-shaped groove exceeding 180 °, the shielding plate can be bent while being rotated from one end side of the groove. And since the outer diameter of a shielding board is larger than the separation distance of the both ends of a groove | channel, the shielding board once inserted does not jump out of a groove | channel. Therefore, stable assembly can be performed without using assembly parts such as bolts.

  It is preferable that the shielding plate has a locking member that prevents dropping. Although the shielding plate fitted in the arc-shaped groove exceeding 180 ° does not jump out, it can be rotated, and is preferably locked. Moreover, the arbitrary-shaped shielding board will not be stably assembled only by fitting. Therefore, it is preferable to have a locking member that prevents dropping. The locking member may be formed in a convex shape, for example, so as to be inserted into a concave portion provided in the case wall or the partition wall. At this time, it is preferable that the shielding plate be flexible because the insertion work is easy. Further, if the locking member is manufactured integrally by molding when the shielding plate is manufactured, sufficient strength can be obtained and the manufacturing cost can be reduced.

  The shielding plate is preferably formed so as to leave a part of the opening so that the gas can flow without completely covering the entire opening. Further, the shielding plate may have an oil drain port through which a small amount of lubricating oil reaching the communication chamber from the case internal space is recirculated.

  In the transmission of the present invention configured as described above, the shielding plate covers most of the opening. Therefore, when the transmission gear scoops up and disperses the lubricating oil to lubricate the rotating part, the amount of lubricating oil passing through the shielding plate is very small. Further, even if the lubricating oil passes through the shielding plate and reaches the communication chamber, the inside of the air breather provided on the upper case wall hardly leaks against gravity. Eventually, the lubricating oil recirculates from the oil vent to the case internal space, and leakage is reliably prevented. In addition, the case internal space and the outside communicate with each other through the remaining opening through the communication chamber and the air breather, and there is no problem in the respiratory function.

The assembly of the shielding plate provided in the transmission of the present invention does not require mounting parts such as bolts, and there is no risk of dropping or dropping by simply fitting into the groove without using an assembly tool. . By providing the shielding plate and the arc-shaped groove, leakage of the lubricating oil can be reliably prevented. In addition, the material cost was reduced by reducing the number of parts, and the labor cost was reduced by simplifying the assembly work, resulting in an oil leakage prevention structure with excellent overall economy.

  The best mode for carrying out the present invention will be described in detail with reference to FIGS. FIG. 1 is a diagram illustrating a transmission 1 according to an embodiment of the present invention, and is a partial cross-sectional view showing an enlarged upper portion of a case 2. On the upper part of the side wall 21 of the case 2, a substantially cylindrical shaft support wall 22 that protrudes substantially horizontally toward the internal space of the case 2 is provided. A shift and select shaft 90 that controls the meshing of a transmission gear (not shown) passes through the shaft support wall 22. The shift-and-select shaft 90 is pivotally supported by a bearing portion 91 provided on the inner surface of the shaft support wall 22 so that it can move in the axial direction and rotate around the shaft.

  An upper wall 23 of the case 2 is provided so as to surround the shaft support wall 22 from the side of the outer peripheral side of the shaft support wall 22 upward and with a gap. FIG. 2 is an enlarged cross-sectional view of the upper part of the case 2 as seen from the XX direction of FIG. As shown in FIG. 2, the upper wall 23 has an arc-shaped cross section that opens downward, and its central angle is larger than 180 °. Partition walls 24, 25 are provided between the both sides of the shaft support wall 22 and the facing portion of the upper wall 23. The shaft support wall 22 and the partition walls 24 and 25 are integrated to define an internal space of the case 2 and form the communication chamber 3 with the upper wall 23. A part of the upper wall 23 forming the communication chamber 3 is perforated as shown in FIG. 1, and an air breather 4 is provided. Further, a gap between the end portion of the shaft support wall 22 protruding toward the internal space of the case 2 and the upper wall 23 is an opening 31 of the communication chamber 3.

  The air breather 4 includes a main body portion 41, a cap portion 42, a packing portion 43, and a pressing spring portion 44. The main body 41 is a substantially vertical cylindrical member fixed to the upper wall 23, and the lower side is open to the communication chamber 3. The cap part 42 is an upper closed cylindrical member disposed with a gap provided on the outer peripheral side of the main body part 41. The packing part 43 is a disk-shaped member that is placed on the upper surface of the main body part 41 and has a diameter similar to that of the main body part, and is made of synthetic rubber. The pressing spring portion 44 is formed of a coiled spring, and is disposed between the packing portion 43 in the cap portion 42. When the internal pressure of the case 2 is balanced with the outside air, the pressing spring portion 44 pushes down the packing portion 43 to seal the upper opening of the main body portion 41 so that airtightness is maintained. When the internal pressure of the case 2 increases, an internal pressure larger than the pressing force of the pressing spring portion 44 pushes up the packing portion 43 so that the gas in the case 2 is released from the upper opening of the main body portion 41 through the gap with the cap portion 42. It has become. Thereby, the rise in internal pressure is suppressed.

  A groove 26 having a rectangular cross section is provided on the inner wall surface of the upper wall 23 forming the opening 31 over the entire arc direction. The shielding plate 5 is fitted into the groove 26.

  The shielding plate 5 has an arcuate outer arc member 51 having an outer diameter substantially equal to the diameter of the bottom surface of the groove 26 and a central angle substantially equal to that of the upper wall 23, and an outer diameter of the outer arc member 51. A circular arc-shaped inner arc member 52 having a center angle substantially equal to that of the upper wall 23, and a coupling member 53 that couples the outer arc member 51 and the inner arc member 52 while being displaced in the axial direction. Are integrally formed. 3A is an explanatory view of the shielding plate 5 viewed from the axial direction, and FIG. 3B is a cross-sectional view taken along the line YY. An inner diameter of the inner arc member 52 is slightly larger than an outer diameter of the support wall 22, and a gap is left between the two so as to allow gas to flow therethrough. In addition, a contact protrusion 54 that protrudes toward the communication chamber 3 is provided at one end of the inner arc member 52, and a wedge-shaped locking protrusion 55 that protrudes toward the communication chamber 3 and has a large lower protrusion dimension at the other end. Is provided. 3C is a cross-sectional view of the contact protrusion 54, and FIG. 3D is a cross-sectional view of the lock protrusion 55, which corresponds to a lock member. The shielding plate 5 is manufactured by molding using a flexible nylon resin.

  Next, an assembly work method for fitting the shielding plate 5 into the groove 26 will be described. First, the shield plate 5 is inserted from one end side of the groove 26 with the end on the contact projection 54 side as the head. At this time, by bending the shielding plate 5, the contact protrusion 54 can pass through without passing through the end of the one partition wall 25. Next, it inserts in order, rotating the shielding board 5. FIG. FIG. 4A shows a state in which the shielding plate 5 is fitted to the middle of the groove 26. Further, when the shielding plate 5 is rotated and fitted, the locking projection 55 comes into contact with the one partition wall 25. Here, if a little large force is applied, the wedge-shaped locking projection 55 passes through the partition wall 25 while being bent and escaping. Finally, the leading contact protrusion 54 contacts the other partition wall 24, and the assembling work is completed in the state shown in FIG.

  Since the external force does not act on the shielding plate 5 once fitted and it does not bend, the contact protrusion 54 and the locking protrusion 55 contact the partition walls 24 and 25 to prevent rotation. Thereby, it will be in the state assembled stably. Since the outer diameter of the outer arc member 51 of the shielding plate 5 is larger than the separation distance between both ends of the groove 26, the shielding plate 5 falls even if the contact projection 54 and the locking projection 55 are not provided. There is nothing. The contact protrusions 54 and the locking protrusions 55 prevent the shield plate 5 from dropping off and can be replaced with other means.

  According to the transmission 1 of the embodiment, by fitting the shielding plate 5 into the groove 26, most of the opening 31 is covered, and a slight gap remains between the shielding plate 5 and the shaft support wall 22. It is only done. Therefore, most of the lubricating oil scattered from the internal space of the case 2 is blocked by the shielding plate 5. Further, even if a small amount of lubricating oil reaches the communication chamber 3, the momentum of scattering is lost, so that it does not leak from the air breather 4 against gravity. On the other hand, if a gap is left even a little, the gas can flow, so there is no obstacle to the respiratory function. In addition, assembling parts such as bolts are not necessary for assembling the shielding plate 5 into the groove 26, and the shielding plate 5 may be fitted while being rotated manually. As a result, the number of parts can be reduced and the assembling work can be simplified.

  The present invention can be widely applied regardless of the structure of the transmission gear and the transmission control system as long as the transmission has a lubricating mechanism of a system in which lubricating oil is enclosed in a case and scooped up.

It is a figure explaining the transmission of the Example of this invention, and is the fragmentary sectional view which expanded and showed the upper part of the case. It is the upper part expanded sectional view of the case seen from another direction in the Example of FIG. 1, and has shown the state before attaching a shielding board. It is explanatory drawing explaining the shielding board used for the Example of FIG. 1, (a) is the figure seen from the axial direction, (b) is sectional drawing from an arrow, (c) is sectional drawing of a contact protrusion, (d ) Shows a sectional view of the locking projection. FIG. 2 is a diagram for explaining an assembly work method for fitting the shielding plate into the groove in the embodiment of FIG. 1, (a) is a state in which the shielding plate is fitted to the middle of the groove, and (b) is a completion of the assembly work. Each state is shown.

Explanation of symbols

1: Transmission 2: Case 21: Side wall 22: Shaft support wall 23: Upper wall 24, 25: Partition wall 26: Groove 3: Communication chamber 31: Opening part 4: Air breather 41: Main body part 42: Cap part 43: Packing part 44: Pressing spring portion 5: Shielding plate 51: Outer arc member 52: Inner arc member 53: Connecting member 54: Abutting projection 55: Locking projection 90: Shift and select shaft 91: Bearing portion

Claims (5)

A case enclosing lubricating oil for lubricating the rotating part, a speed change mechanism comprising a power transmission shaft and a transmission gear housed in the case, and a communication formed between the case and the outside formed at the top of the case An air breather that is provided between the communication chamber and the outside of the communication chamber and breathes in response to a change in the internal pressure of the case; A transmission comprising a shielding plate,
The case has an arc-shaped groove along an inner wall surface defining the communication chamber, and the shielding plate has an arc-shaped outer arc portion and is inserted from one end side of the arc-shaped groove and rotated to fit. A transmission characterized by being worn. The transmission according to claim 1, wherein a center angle of the arc-shaped groove exceeds 180 °.   The transmission according to claim 1, wherein the shield plate has a locking member that prevents the shield plate from falling off.   The transmission according to claim 1, wherein the shielding plate is made of a flexible material.   The transmission according to claim 4, wherein the flexible material is nylon resin.

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