JP3757765B2 - Transmission case structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention accommodates a gear transmission mechanism having a transmission gear and a lubricating oil that lubricates the gear transmission mechanism, and allows the power to be taken out from the gear transmission mechanism, so that a power take-out shaft can be inserted. The present invention relates to a case structure for a transmission.
[0002]
[Prior art]
In recent years, as the speed of vehicles has been increased, the rotational speed of the output shaft can be increased depending on the selected gear position of the transmission, and the synchronization device used in the transmission can be improved to improve the operability of the manual transmission. Corning is progressing. Therefore, in a transmission that does not have a forced cooling device for lubricating oil housed inside the transmission, the internal lubricating oil is agitated at high speed by the rotation of the transmission gear and the multi-cone, It is forced to be very hot and harsh.
[0003]
At present, as a countermeasure against the high temperature of the lubricating oil, generally, the amount of the lubricating oil to be used is reduced as much as possible, or the rib formed on the outer side of the transmission case is increased to move from the case to the outside air. Measures such as increasing the amount of heat released are taken. In some commercial vehicles, an aluminum die-cast lid with a heat-dissipating rib on the outside is used as a lid for the power take-off shaft (PTO shaft) set on the side of the transmission case. Some are doing it.
[0004]
As a cooling device for the lubricating oil in the differential case, a cooling fin formed in a row in parallel with the outer surface of the differential case is disclosed in, for example, Japanese Utility Model Laid-Open No. 60-12091. . According to this cooling device, at least two rows of cooling fins are arranged in the front-rear direction, and the cooling fins are alternately arranged in adjacent cooling fin rows, so that the cooling air flowing between the cooling fins is adjacent to the cooling fin row. The cooling fin row collides with the end of the cooling fin to improve the cooling efficiency.
[0005]
In addition, in order to obtain a rotational coupling between the vehicle transmission and the power take-off device (PTO device), what has already been proposed by the present applicant as a lid structure for closing an opening formed in the case of the transmission is particularly This is disclosed in Kaihei 11-159601. This lid structure is composed of a flange in which a lid for closing the opening is overlapped and joined to the outer surface of the side wall, and a box-shaped closure portion protruding from the flange through the opening to the inside of the case. A reinforcing rib is provided on the top and the height of the reinforcing rib is changed to display characters or symbols so that the vertical relationship can be visually recognized on the outer surface of the lid.
[0006]
In the structure of the case of the transmission, the inner surface of the case is formed in a curved surface corresponding to the outer diameter of the gear disposed inside the case, and the lid that closes the opening for taking out the power is also included in the case. The inner surface is formed on the curved surface so as to be smoothly connected to the curved surface. Therefore, the mounting posture of the lid is limited so that the inner surface smoothly connects with the curved inner surface of the case. An operator can prevent erroneous attachment by attaching the lid to the case in accordance with a display in which the vertical relationship provided on the outer surface of the lid is visible.
[0007]
[Problems to be solved by the invention]
By the way, the high temperature oil environment in which the temperature of the lubricating oil in the case of the transmission becomes high has an adverse effect such as deteriorating the lubricating oil. This will significantly shorten the tooth surface fatigue life. The current cooling measures for lubricating oil are still insufficient for cooling the lubricating oil in the case, and further measures for reducing the lubricating oil temperature are desired. Conventionally, a plate press product is generally used as the lid for closing the opening for power take-off. The lid of the pressed plate product is molded with low rigidity and thin plate thickness, so the lid itself generates membrane vibration and transmitted sound, and as a result, radiated sound (noise) from the transmission is generated. easy.
[0008]
Therefore, in order to release the heat of the lubricating oil in the case of the transmission to the outside of the case and promote the cooling of the lubricating oil, the opening for the power take-off shaft of the transmission case already proposed by the present applicant is closed. There is a problem to be solved in that the lid has a heat dissipation function to further reduce the lubricating oil temperature.
[0009]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and a lid that closes an opening for a power take-off shaft formed in a transmission case is provided with a heat dissipation function that dissipates heat received from lubricating oil to the outside. This allows the heat of the lubricating oil in the case of the transmission to escape to the outside of the case and further accelerates the cooling of the lubricating oil, preventing deterioration of the lubricating oil due to high temperatures and avoiding tooth surface fatigue of the gear. It is to provide a transmission case structure that can be used.
[0010]
As a basic structure of the case structure of the transmission according to the present invention, a gear transmission mechanism having a gear for shifting and a lubricating oil for lubricating the gear transmission mechanism are accommodated and power for taking out power from the gear transmission mechanism is accommodated. A case in which an opening through which the take-out shaft can be inserted is formed in the side wall; and a lid that is attached to the side wall and closes the opening in a state in which the power from the gear transmission mechanism is not taken out, on the inner surface of the lid is formed heat rib for receiving the heat of the lubricating oil, the outer surface of the lid that has been formed is heat radiation ribs for dissipating heat to the outside air.
[0011]
According to this case structure of the transmission, when power is taken out from the gear transmission mechanism, the power take-out shaft is inserted into the opening formed in the side wall, and the opening and the power take-out shaft are sealed by appropriate means. . When power is not extracted from the gear transmission mechanism, the opening is closed by a lid attached to the side wall. When the temperature of the lubricating oil becomes high because the rotating gear agitates the lubricating oil as the gear transmission mechanism operates in the case, the agitated lubricating oil flows in contact with the lid. The heat of the oil is transmitted from the heat receiving rib of the lid that closes the opening to the heat radiating rib, and is finally dissipated to the outside air. Accordingly, the temperature of the lubricating oil is efficiently lowered by heat conduction through the lid.
[0012]
In the case structure of the transmission, the heat receiving ribs are formed in a plurality of substantially parallel rows, and the heat dissipating ribs are formed in a plurality of substantially parallel rows. By forming both ribs side by side in multiple rows, the heat receiving rib contacts the lubricating oil to increase the heat receiving area to receive heat and receive the heat of the lubricating oil uniformly, and the heat radiating rib contacts the outside air As a result, the heat dissipating area for dissipating heat is increased, and the heat transferred from the heat receiving rib is efficiently dissipated to the outside air.
[0013]
According to the case structure of the transmission according to the present invention, the direction in which the rows of the heat receiving ribs extend and the direction in which the rows of the heat radiating ribs extend are substantially orthogonal to each other. By making the extending directions of the heat receiving ribs and the heat radiating ribs substantially orthogonal to each other, the heat received by each heat receiving rib is transmitted to the plurality of heat radiating ribs, so that heat is efficiently transmitted and dissipated. In addition, the transmission case has ribs whose directions are almost perpendicular to each other on the outside and inside, thereby improving the rigidity of the lid and improving the rigidity of the lowered case, and reducing the sound emitted from the case. To do.
[0014]
In the transmission according to the present invention, the longitudinal direction of the transmission is arranged in the vehicle in the longitudinal direction of the vehicle, and the heat radiating rib is provided in a horizontal direction along the longitudinal direction of the transmission, The heat receiving rib is provided substantially perpendicular to the longitudinal direction of the transmission. By providing the heat dissipating ribs in the horizontal direction along the longitudinal direction of the transmission, the flow of outside air around the side wall of the transmission when the vehicle travels is the longitudinal direction of the transmission, that is, the longitudinal direction in which the vehicle travels. Thus, the heat dissipating ribs are in efficient contact with the outside air, and the heat is efficiently dissipated into the outside air. By providing the heat receiving rib substantially at right angles to the longitudinal direction of the transmission, the extending direction of the heat receiving rib is substantially along the flow of the lubricating oil stirred by the rotation of the gear in the case. Agitation resistance is reduced.
[0015]
Said heat receiving ribs, the ridges, with respect to the running direction of the tip of the transmission gear for running nearby to the lid by rotation of the front Symbol transmission gear, are formed with inclined obliquely. Lubricating oil that the transmission gear scrapes up by inclining the heat receiving rib with respect to the rotation direction of the transmission gear, that is, the traveling direction of the gear tip of the transmission gear that travels close to the lid by the rotation of the transmission gear. Is guided by the heat receiving ribs and repelled to the side, and the repelled lubricating oil is guided by grooves and wrinkles formed on the inner surface of the case, and supplied to the necessary parts.
[0016]
The heat receiving rib is provided in a direction substantially perpendicular to the longitudinal direction of the transmission, that is, in a vertical direction along the flow of the lubricating oil stirred by the rotation of the gear in the case. Lubrication agitated by the gears by arranging the direction of the heat receiving rib substantially along the rotation direction of the gears of the gear transmission mechanism of the transmission and along the flow of the lubricating oil agitated by the rotation of the gears. Oil agitation resistance is reduced and power loss in the transmission is reduced. The flow of the lubricating oil in the transmission substantially follows the heat receiving rib, and the heat receiving rib efficiently contacts the lubricating oil, and the heat of the lubricating oil is efficiently absorbed by the outside air heat receiving rib. In addition, by slightly considering the direction of the heat receiving ribs, the flow direction of the lubricating oil in the transmission is corrected, and the supply of the lubricating oil to disadvantageous parts around the oil is improved.
[0017]
The lid is formed integrally with an annular flange portion attached to the side wall, and an inner peripheral side of the flange portion, and is recessed toward the inside of the case when attached to the side wall, and the heat receiving rib A profile formed integrally with a concave portion protruding toward the inside of the case, and a bottom surface of the concave portion facing the inside of the case is smoothly connected to an inner surface of the case in the vicinity of the opening. The front end portion of the heat receiving rib facing the case is formed in a front end profile facing the outer diameter of the transmission gear with a slight gap. By attaching the annular flange portion to the side wall of the case, the concave portion integrally formed on the inner peripheral side of the flange portion enters a state of being recessed toward the inside of the case. By making the inner structure of the lid, especially the profile on the bottom of the recess, smoothly connect to the inner surface of the case, the flow of lubricating oil in the case is continuously smooth without being disturbed by the lid. Therefore, the power loss in the transmission is further reduced, and the amount of necessary lubricating oil stored in the case is reduced. In addition, the tip of the heat receiving rib formed integrally with the concave portion of the lid is formed in a tip profile facing the case with a slight gap between the outer diameters of the gears accommodated in the case. By doing so, the flow of the lubricating oil stirred by the gear is guided more efficiently by the heat receiving rib.
[0018]
The heat-dissipating rib includes a concave-integrated rib formed integrally with the concave portion, and the concave-integrated rib is a plate-like shape that integrally extends outward from the flange portion from the inner bottom surface and the inner side surface of the concave portion. It is formed into a shape. The heat dissipating rib may be integrally formed in the flange portion, but includes at least a recessed portion integrated rib formed integrally with the recessed portion in which the heat receiving rib is formed, and heat is directly transmitted from the recessed portion. It is configured to be. The heat received from the recess-integrated rib to the recess of the lid is transmitted to the heat-dissipating rib integrally extending from the inner bottom surface and the inner side surface formed in the recess of the lid. Since the heat radiating rib is formed in a plate shape extending outward from the flange portion, the heat radiating rib comes into contact with the outside air flowing along the side wall of the transmission and efficiently dissipates heat to the outside air.
[0019]
The case and the lid are made of aluminum die casting. By making the case and lid made of aluminum die-casting, the weight of the transmission is reduced, while the rigidity and strength are reduced, so a reinforcement measure is necessary. The heat receiving rib and the heat radiating rib provided on the lid increase the strength and rigidity of the lid, and in a state where the lid is attached to the side wall of the case, the case is reinforced.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a transmission case structure according to the present invention will be described below with reference to the accompanying drawings. 1 is a front view showing a case outer side of a lid for closing an opening formed in a transmission case, which is an embodiment of a case structure of a transmission according to the present invention, and FIG. 2 is a sectional view of the lid shown in FIG. 3 is a rear view showing the inside of the case of the lid shown in FIG. 1, FIG. 4 is a front view showing another example of the case structure of the transmission according to the present invention, and FIG. 5 shows the entire case structure of the transmission according to the present invention. FIG.
[0021]
As shown in FIG. 5, the case structure of the transmission according to the present invention has an opening 4 which is a window for a power take-off shaft (PTO shaft 9) formed in the case 2 of the transmission 1 and the side wall 3 of the case 2. And a lid 10 for closing. Conventionally, the case 2 is often made of an iron plate press, but is made of an aluminum die cast for weight reduction. The transmission 1 is configured as a transmission, and includes an input shaft 5 to which driving force from the engine is input, a gear transmission mechanism (not shown) that changes the rotation input to the input shaft 5, and a gear transmission mechanism. An output shaft 6 is provided for outputting the rotated rotation. The longitudinal direction of the transmission 1 is a direction indicated by an arrow AA parallel to the paper surface.
[0022]
As shown in FIGS. 1 to 3, the lid 10 is integrated with the flange portion 11 from the inner peripheral side of the flange portion 11 and the annular flange portion 11 that is superimposed on the side wall 3 around the opening 4 of the transmission case 2. It is comprised from the recessed part 12 formed in the state dented in box shape. A plurality (eight) of attachment holes 13 are formed in the flange portion 11 of the lid 10 at substantially equal intervals. When the lid 10 is attached to the side wall 3 of the case 2 by screwing the mounting screw 21 inserted through the mounting hole 13 into the case 2, the concave portion 12 of the lid 10 is recessed from the opening 4 of the side wall 3 toward the inside of the case 2. It enters the state.
[0023]
The bottom surface 14 of the recess 12 of the lid 10 is formed in a profile that smoothly connects to an inner wall surface 19 (shown by an imaginary line in FIG. 2) formed in the vicinity of the opening 4 of the case 2. Since the inner wall surface 19 below the opening 4 is curved, a part of the bottom surface 14 of the recess 12 is also formed into a curved surface profile according to the curved inner wall surface 19. By forming the bottom surface 14 of the recess 12 in a profile that smoothly connects with the inner wall surface 19, the volume of the case 2 becomes as small as possible, and the amount of lubricating oil accommodated in the case 2 is reduced. The agitation resistance of the lubricating oil by the gear rotating within 2 is also reduced.
[0024]
On the front side of the lid 10, a plurality of rows of heat dissipating ribs 15 (partially denoted by reference numeral 15) extending in the horizontal direction are also formed integrally with the lid 10 to serve as reinforcement for the lid 10. The heat radiating rib 15 includes flange-integrated ribs 15 a and 15 b that are integrally formed with the flange portion 11, and recess-integrated ribs 15 c and d that are integrally formed with the recess 12. The flange-integrated rib includes a rib 15a that extends over the entire width of the lid 10, and a rib 15b that is formed by being divided over a range excluding the mounting hole 13 and the vicinity thereof when intersecting the mounting hole 13. The recess-integrated rib includes a rib 15c extending to the flange portion 11 and extending over the entire width of the lid 10, and a rib 15d having a length extending substantially only to the width of the recess 12. Other forms can of course be employed. In the recess 12, the recess-integrated ribs 15 c and 15 d extend integrally from the inner bottom surface 16 and the inner side surface 17 of the recess 12, and serve as heat transfer from the recess 12 and reinforcement of the recess 12. However, the rows of the heat radiating ribs 15 are arranged in parallel to each other, and are formed so as to extend to the same height with respect to all types of the heat radiating ribs 15.
[0025]
On the front side of the lid 10, the heat radiating ribs 15 are installed along the longitudinal direction (A-A) of the transmission 1, that is, the vehicle front-rear direction. When the vehicle travels, the air flow around the transmission 1 is in the vehicle direction, that is, the longitudinal direction of the transmission. Accordingly, on the front side of the lid 10, the outside air flows along the direction in which the heat dissipating ribs 15 extend, so that heat is efficiently radiated from the heat dissipating ribs 15 to the air.
[0026]
On the back side of the lid 10, that is, the side facing the inside of the case 2, a plurality of rows of heat receiving ribs 18 extending in the vertical direction perpendicular to the heat radiating ribs 15 are formed integrally with the lid 10. By providing a plurality of rows of heat receiving ribs 18 inside the case 2 of the recess 12, the heat receiving area that receives heat from the lubricating oil of the lid 10 increases. The heat receiving ribs 18 are formed in parallel rows. Further, the direction in which the heat receiving rib 18 extends is set at a substantially right angle to the longitudinal direction of the transmission 1, and therefore coincides with the direction in which the gear tip of the speed change gear travels close by the rotation of the speed change gear. Direction. Since this direction is a direction along the flow of the lubricating oil generated in the case 2 when being agitated by the rotation of the transmission gear or the like, the agitating resistance of the lubricating oil is reduced.
[0027]
Furthermore, in consideration of the oil circulation property in the transmission 1, the extending direction of the heat receiving rib 18 can be set so that the lubricating oil is scattered toward the portion where the lubricating oil tends to be insufficient. 4 is a rear view showing the inside of the case corresponding to FIG. 3 showing another example of the lid for closing the opening 4 formed in the case 2 in the case structure of the transmission according to the present invention. 30 consists of the annular flange part 31 and the recessed part extended integrally from the inner peripheral side. Heat receiving ribs 38 extending integrally from the outer bottom surface of the recess of the lid 30 is a substantially vertical direction addendum of the transmission gear coincides with the direction of travel in close proximity by the rotation of the transmission gear, its ridge The upper part is formed to be slightly inclined with respect to the vertical direction. When the gear is rotated by the operation of the gear transmission mechanism and the lubricating oil is scraped up, the direction of the lubricating oil scraping is changed in the lubricating oil guide feed passage formed between the inclined heat receiving rib 38 and the outer bottom surface 34. As indicated by the arrow J in FIG. 4, the supply direction of the lubricating oil can be determined toward the portion where the lubricating oil tends to be insufficient. In FIG. 4, reference numeral 33 denotes a mounting hole.
[0028]
Since the heat-dissipating rib 15 and the heat-receiving rib 18 have a reinforcing action, the rigidity of the lid 10 itself is improved and the rigidity of the side wall 3 of the case 2 when the lid 10 is attached to the case 2 is also increased. Can do. In particular, since the extending direction of the heat-dissipating rib 15 and the heat-receiving rib 18 is perpendicular to the vehicle front-rear direction and the direction intersecting with each other, any axial extension and compression, and any axis bending Therefore, the lid 10 has a small deformation amount regardless of the axial force in any axial direction and the bending around any axis. When the opening 4 is formed in the side wall 3 of the case 2 of the transmission 1, the rigidity of the case 2 is reduced due to the presence of the opening 4 itself. By closing the opening 4 with 10, the rigidity of the side wall 3 of the case 2 can be increased.
[0029]
As can be seen from the description of FIG. 5, the heat dissipation rib 15 of the lid 10 is along the longitudinal direction of the transmission 1, that is, the front-rear direction of the vehicle to which the transmission 1 is attached. When the vehicle travels, outside air around the transmission 1 flows along the longitudinal direction of the transmission 1, and also flows equally along all the heat dissipating ribs 15 provided on the lid 10 in the lid 10. Accordingly, heat is radiated on average from the lid 10, which has received heat from the lubricating oil that has become high temperature, without increasing the amount of heat radiated from the specific heat radiating rib 15.
[0030]
FIG. 6 shows a partial cross-sectional view of the transmission 1 shown in FIG. The gear transmission mechanism 7 is provided on the main shaft 8A, a plurality of gears 8 provided on the main shaft 8A, a counter shaft 9A that is disposed in parallel with the main shaft 8A and rotatably supported by the case 2, and the counter shaft 9A. The gears 9 are arranged so as to mesh with the gears 8, and the rotation of the input shaft is changed at a predetermined gear ratio by selecting a gear train with the gears 9 meshed with the gears 8. And output to the output shaft.
[0031]
As already shown in FIG. 2, the outer bottom surface 14 of the recess 12 of the lid 10 is smoothly connected to the inner wall surface 19 of the case 2 around the opening 4 for disposing the power take-off shaft (PTO shaft). The stirring resistance of the lubricating oil is reduced, and the amount of lubricating oil stored in the case 2 is reduced. Further, the heat receiving rib 18 has a rib end surface 20 that becomes a smooth tip profile along a tooth tip circle around which a tooth tip of a transmission gear (in this example, a gear 9 provided on the counter shaft 9A) rotates. ing. Therefore, the lubricating oil scraped up by the gear 9 is efficiently guided by the outer bottom surface 14 of the recess 12 and the heat receiving rib 18, the stirring resistance of the lubricating oil is reduced, and the heat from the lubricating oil that has reached a high temperature is reduced. It is efficiently transmitted to the heat receiving rib 18 through a wide contact area. Any of the heat receiving ribs 18 transfers heat to the plurality of heat radiating ribs 15 via the recesses 12, and the heat transferred to the heat radiating ribs 15 forms a plurality of rows along the longitudinal direction of the transmission. Heat is efficiently radiated from the heat radiating ribs 15 to the outside air. As a result, the heat of the lubricating oil may of course be directly cooled through the wall portion of the case 2, but the lid 10 can be easily transmitted from the heat receiving ribs 18 to the heat radiating ribs 15 to improve the efficiency of the lubricating oil. It can cool well.
[0032]
【The invention's effect】
Since the case structure of the transmission according to the present invention is configured as described above, the following effects can be obtained. That is, in the case structure of this transmission, the lid for closing the power extraction opening of the case has a heat receiving rib for receiving the heat of the lubricating oil formed on the inner surface of the cover, and on the outer surface of the cover. A heat dissipating rib is formed to dissipate heat to the outside air, and it has a heat dissipating function to dissipate heat received from the lubricating oil to the outside, so that the rotating gear receives lubricating oil as the gear transmission mechanism operates in the case. When the temperature of the lubricating oil is increased by stirring, the heat received efficiently from the lubricating oil by the heat receiving rib having an increased contact area with the lubricating oil is transferred to the outside of the case, that is, outside air through the heat radiating rib. Escaped. Accordingly, the cooling of the lubricating oil is further promoted, the deterioration of the lubricating oil due to the high temperature can be prevented, and the tooth surface fatigue of the gear can be avoided. In addition, the case of the transmission has conventionally been generally used as a plate press, but due to the relationship between rigidity and plate thickness, for the radiated sound (noise) from the transmission such as membrane vibration and transmitted sound, Although the contribution was great, according to the case structure of this transmission, even if the case is made of aluminum die-casting, it has both a heat-receiving rib and a heat-dissipating rib on the inner and outer sides, so both ribs As a result of the substantially orthogonal arrangement, the rigidity of the cover confidence is improved, and the radiated sound can be reduced.
[0033]
In addition, by slightly considering the direction of the heat receiving ribs formed in the vertical direction inside the lid, it is possible to correct the direction of the lubricating oil scooping up inside the transmission, and to the place where oil supply is difficult Therefore, it is possible to improve the lubrication of disadvantageous parts around the oil. Furthermore, by setting the inner wall shape of the lid along the inner wall surface of the case near the opening for the power take-off shaft (TPO shaft), or by setting it to a position close to the tooth tip diameter of the gear for shifting, it is necessary in the case. Lubricating oil amount is reduced. Still further, the rigidity of the case is lowered by providing a take-out opening for the power take-off shaft formed on the side wall of the case. However, for closing the take-out opening, the case is, for example, substantially orthogonal between the outside and the inside. By attaching a highly rigid lid with ribs to the opening, the reduced case stiffness can be improved.
[Brief description of the drawings]
FIG. 1 is a front view showing an outer side of a case of a lid that closes an opening formed in a transmission case, which is an embodiment of a case structure of a transmission according to the present invention.
FIG. 2 is a cross-sectional view of the lid shown in FIG.
3 is a rear view showing the inside of the case of the lid shown in FIG. 1. FIG.
4 is a rear view showing the inside of the case corresponding to FIG. 3 showing another example of a lid for closing an opening formed in the case in the case structure of the transmission according to the present invention. FIG.
FIG. 5 is a side view showing the entire case structure of the transmission according to the present invention.
6 is a partial cross-sectional view showing a cross section of the transmission 1 shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Transmission 2 Case 3 Side wall 4 Opening 10, 30 Lid 11, 31 Flange part 12 Recessed part 14, 34 Outer bottom face 15 Radiation rib 16 Inner bottom face 17 Inner side face 18, 38 Heat receiving rib 19 Inner wall face 20 Rib end face

Claims (5)

A case in which an opening is formed in the side wall that accommodates a gear transmission mechanism having a gear for transmission and a lubricating oil that lubricates the gear transmission mechanism and through which a power take-out shaft for taking out power from the gear transmission mechanism can be inserted; And a lid that is attached to the side wall and closes the opening in a state where power from the gear transmission mechanism is not taken out, and a heat receiving rib that receives the heat of the lubricating oil is formed on the inner surface of the lid, In the case structure of the transmission in which a heat-dissipating rib for radiating heat to the outside air is formed on the outer surface of the lid ,
The direction in which the rows of the heat receiving ribs extend and the direction in which the rows of the heat dissipating ribs extend are substantially orthogonal to each other,
The transmission is disposed in the vehicle with its longitudinal direction facing the vehicle front-rear direction, the heat dissipating rib is provided in a horizontal direction along the longitudinal direction of the transmission, and the heat receiving rib is A case structure of a transmission comprising being provided substantially perpendicular to the longitudinal direction of the transmission. The ridge line of the heat receiving rib is formed so as to be inclined with respect to the traveling direction of the tooth tip of the transmission gear that travels close to the lid by the rotation of the transmission gear. The case structure of the transmission as described in 2. The lid is formed integrally with an annular flange portion attached to the side wall, and an inner peripheral side of the flange portion, and is recessed toward the inside of the case when attached to the side wall, and the heat receiving rib A profile formed integrally with a concave portion protruding toward the inside of the case, and a bottom surface of the concave portion facing the inside of the case is smoothly connected to an inner surface of the case in the vicinity of the opening. And a tip portion of the heat receiving rib facing the case is formed in a tip profile facing the outer diameter of the speed change gear with a slight gap therebetween. case structure for a transmission according to claim 1 or 2. The heat-dissipating rib includes a concave-integrated rib formed integrally with the concave portion, and the concave-integrated rib is a plate-like shape that integrally extends from the inner bottom surface and inner side surface of the concave portion to the external force of the flange portion. The transmission case structure according to claim 3 , wherein the transmission case structure is formed. The case structure of the transmission according to any one of claims 1 to 4 , wherein the case and the lid are made of aluminum die casting .

Images