JP5095192B2 - Lubricating structure for vehicle transmission - Google Patents

Description

  The present invention relates to a lubrication structure for a vehicle transmission, and more particularly to a lubrication structure for a vehicle transmission that can reduce agitation resistance of lubricating oil as much as possible and ensure good lubrication.

  Vehicle transmissions are, for example, belt-type continuously variable transmissions, forward / reverse switching mechanisms for forward / reverse switching, differential devices that transmit power to the left and right drive wheels, and the output of the continuously variable transmission is decelerated and transmitted to the differential device The reduction mechanism and the like are housed in a common transmission case and unitized to achieve compactness. An oil pan for storing lubricating oil is attached to the lower part of the transmission case.

  The lubrication of the continuously variable transmission, the forward / reverse switching mechanism, the speed reduction mechanism, the differential device, etc. arranged in the transmission case is a forced lubrication in which the lubricating oil in the oil pan is pumped to the lubricated part by an oil pump and lubricated. This is performed by oil bath lubrication in which the lower end portion of the final gear of the rotating differential device is immersed in and lubricated with lubricating oil stored in a lubricating oil reservoir formed at the bottom of the transmission case. Lubricating oil is used as hydraulic oil for controlling the continuously variable transmission and the forward / reverse switching mechanism.

  In this forced lubrication and hydraulic control, a valve body that constitutes a hydraulic circuit is provided inside the transmission case, and the lubricating oil in the oil pan is supplied to the hydraulic servo, valve and other elements in the valve body by an oil pump. The transmission and forward / reverse switching mechanism are controlled, and lubricating oil from the oil pump is supplied for cooling or lubrication of each part. Thus, the lubricating oil used for lubrication and control of each part flows down along the inner wall surface of the transmission case, or is collected in the oil pan by a return pipe or the like and recirculated.

  On the other hand, the differential device includes a hollow differential case that extends in the vehicle width direction at the rear of the vehicle body of the forward / reverse switching mechanism and is rotatably supported by the transmission case, and a reduction mechanism that is integrally attached to the differential case. And a final gear that is rotationally driven through the gear mechanism, and is configured to transmit power to the left and right wheels from the gear mechanism in the differential case.

  The predetermined lubricating oil is stored in the lubricating oil reservoir so that the lower end portion of the final gear is always immersed in the lubricating oil even when the vehicle is traveling on a slope or a turning circuit.

  Such a vehicle transmission incorporates a differential device in the transmission case and immerses and lubricates the lower end portion of the final gear in the lubricating oil. There is a concern that the weight increases and the amount of the lubricating oil swung by the final gear increases due to the viscosity of the lubricating oil during high-speed rotation, and the agitation resistance increases, leading to deterioration of fuel consumption and deterioration of the lubricating oil. This increase in the agitation resistance is caused by the fact that the lubricating oil stored in the oil pan or transmission moves to the differential device side and the part where the final gear etc. is immersed in the lubricating oil becomes relatively large when the vehicle is climbing or accelerating. Also occurs.

  As a countermeasure, if the lubricating oil in the oil pan is reduced, the lubricating oil may move forward in the transmission case when the vehicle travels on a downhill or when the vehicle is decelerated, resulting in insufficient lubrication of the final gear or the like. In addition, when climbing or accelerating, the lubricating oil in the oil pan decreases and the oil pump does not sufficiently suck the lubricating oil, which causes a lack of control hydraulic pressure or insufficient forced lubrication. In addition, there is a concern that the lubricating oil may move in the transmission case due to the lateral acceleration, that is, the so-called lateral G, during turning, and the same problem may occur.

  As countermeasures, various lubricating structures for securing lubricating oil and suppressing stirring resistance have been proposed. For example, in Patent Document 1 and Patent Document 2, a small hole is formed in the lower surface of a transmission case in which a lubricating oil reservoir for storing lubricating oil is formed, close to the lower end portion of a gear that is rotatably stored. There is disclosed a lubrication structure in which a cover plate or a baffle plate is provided and the amount of lubricating oil immersed in the gear during high rotation is limited to suppress stirring resistance and increase in temperature of the lubricating oil.

  In Patent Document 3 and Patent Document 4, a tank member that opens opposite to the gear immersed in the lubricating oil in the transmission case is disposed, and the lubricating oil in the transmission case is rotated by the gear when the oil temperature is high. Thus, it is disclosed that the oil level in the transmission case is adjusted by letting it escape into the tank and returning the lubricating oil in the tank member to the transmission case or the oil pan during low temperature oil.

Japanese Utility Model Publication No. 58-6042 Japanese Utility Model Publication No. 61-1771 Japanese Utility Model Publication No. 3-125941 Japanese Utility Model Publication No. 4-62950

  According to Patent Document 1 and Patent Document 2, a cover plate or baffle plate is provided in the vicinity of the lower end portion of a gear that is rotatably accommodated to limit the amount of lubricating oil that the gear is immersed in. Stirring resistance and temperature rise of lubricating oil can be suppressed.

However, the lubricating oil of the vehicle moves the lubricating oil in front of the plates and the baffle plate covering the or deceleration when traveling downhill, also uphill time and acceleration Kutsugaesara or baffle within the plate during moves backward There is a risk that the amount of lubricating oil in which the gear is immersed will be reduced, resulting in insufficient lubrication. Further, since the cover plate and the baffle plate are provided, the structure becomes complicated, and there is a concern about an increase in the size and weight of the transmission.

  On the other hand, according to Patent Document 3 and Patent Document 4, when the oil temperature is high, the lubricating oil in the transmission case is released into the tank, and when the oil temperature is low, the lubricating oil in the tank member is returned to the transmission case or the oil pan to adjust the oil level. can do.

  However, when the vehicle travels downhill or when the vehicle is decelerated, the oil in the transmission case whose oil level has been adjusted moves forward. There is a possibility that the amount of lubricating oil to be soaked changes greatly, resulting in an increase in stirring resistance and insufficient lubrication.

  Accordingly, an object of the present invention made in view of such a point is to provide a lubricating structure for a vehicle transmission that is excellent in lubricity, can reduce the stirring resistance by the gear mechanism, and can reduce the amount of stored lubricating oil. There is to do.

The invention of the lubricating structure for a vehicle transmission according to claim 1 that achieves the above-described object is a transmission case in which a lubricating oil reservoir portion in which lubricating oil is stored is formed in an inner lower portion, and the lubricating oil reservoir portion. In a lubricating structure for a vehicle transmission provided with a gear that is rotatably immersed in a transmission case with a lower end portion immersed in the lubricating oil, the desired oil surface height of the lubricating oil stored in the lubricating oil reservoir a suction port opened to the transmission case in communication with the lubricant reservoir in position, the lubricating oil tank and a lubricating oil suction circuit for communicating the suction port and the lubricating oil tank, lubricating oil tank and the above transmission case Doo and the lubricating oil return circuit lubricating oil in the lubricating oil tank is communicated to be falling within the transmission case, and the Jun by the intake pipe negative pressure of the engine And the lubricating oil tank pressure reducing means repeating the atmosphere opening of reduced pressure and the lubricating oil tank in the oil tank, further comprising a characterized.

According to this invention, the lubricant stored in the lubricant reservoir in the transmission is passed through the lubricant intake circuit from the suction port by repeatedly reducing the pressure in the lubricant tank and releasing to the atmosphere by the lubricant tank decompression means. The lubricating oil that is sucked into the lubricating oil tank and stored, and the lubricating oil in the lubricating oil tank is returned to the transmission case via the lubricating oil return circuit, and stored in the lubricating oil reservoir in the transmission case. The oil level is maintained at the height of the suction port so that there is no excess or deficiency in the lubricating oil reservoir under various conditions such as changes in the body posture, acceleration and deceleration, and changes in the temperature of the lubricating oil. Stirring loss is suppressed by the stirring resistance of the gear without increasing the amount of immersion in which the lower end portion of the gear is immersed in the lubricating oil while maintaining the desired oil level position. In addition, since the amount of lubricating oil in the lubricating oil reservoir is optimally maintained and the lack of lubrication due to the lack of lubricating oil can be avoided, it is possible to reduce the amount of lubricating oil that has been stored in advance in order to cope with the lack of lubrication. become.

  Further, the lubricating oil stored in the lubricating oil reservoir is stored by sucking the lubricating oil in the lubricating oil reservoir into the lubricating oil tank by the negative pressure of the intake pipe of the engine and returning the lubricating oil stored in the lubricating oil tank to the transmission case. Since the oil level is controlled, new driving means such as an electric motor is not required, and an increase in the size of the transmission, simplification of the configuration, and increase in manufacturing cost can be suppressed.

According to another aspect of the invention of the lubricating structure for a vehicle transmission that achieves the above object, the transmission case includes a transmission chamber that houses the transmission, and a lubricating oil reservoir that stores the lubricating oil in the lower portion. A vehicle transmission that is partitioned by a partition wall into a power transmission mechanism chamber that houses a differential device having a final gear immersed in a lubricating oil stored in a lubricating oil reservoir at a lower end portion connected to the machine so that power can be transmitted In the lubricating structure, a suction port that opens to the transmission case in communication with the lubricating oil reservoir at a desired oil level of the lubricating oil stored in the lubricating oil reservoir, a lubricating oil tank, and the suction and the lubricating oil suction circuit that communicates the mouth and lubricating oil tank, and a lubricating oil tank and the power transmission mechanism compartment falling capable to lubricating oil power transmission mechanism chamber in the lubricating oil tank And the lubricating oil return circuit for passing, characterized in that and a lubricating oil tank pressure reducing means repeating the atmosphere opening of reduced pressure and the lubricating oil tank in the lubricating oil tank by the intake pipe negative pressure of the engine.

According to the present invention, the lubricant stored in the lubricating oil reservoir in the power transmission mechanism chamber is supplied from the suction port to the lubricating oil suction circuit by repeatedly reducing the pressure in the lubricating oil tank and releasing to the atmosphere by the lubricating oil tank pressure reducing means. The level of the lubricating oil that is sucked and stored in the lubricating oil tank, and the lubricating oil in the lubricating oil tank is returned to the power transmission mechanism chamber via the lubricating oil return circuit and stored in the lubricating oil reservoir. Is held at the desired height of the suction port, and the stirring loss is suppressed by the stirring resistance of the final gear. In addition, since the lubrication amount in the lubrication oil reservoir is optimally maintained and the lack of lubrication due to the lack of lubrication oil can be avoided, it has been possible to reduce the lubrication oil that has been stored in advance with sufficient margin to cope with the lack of lubrication oil. It becomes possible.

  According to a third aspect of the present invention, in the lubricating structure for a vehicle transmission according to the first or second aspect, the reverse of allowing the lubricating oil return circuit to flow the lubricating oil from the lubricating oil tank side to the transmission case side. A stop valve is provided.

  According to the present invention, when the inside of the lubricating oil tank is depressurized and the lubricating oil in the lubricating oil reservoir is sucked into the lubricating oil tank from the suction port via the lubricating oil suction circuit, the check valve is closed and the inside of the transmission case is closed. The lubricating oil and air are prevented from being introduced into the lubricating oil tank through the lubricating oil return circuit.

  According to a fourth aspect of the present invention, in the lubricating structure for a vehicle transmission according to any one of the first to third aspects, the lubricating oil tank pressure-reducing means includes a negative pressure source circuit having one end communicating with the engine intake pipe. An outside air introduction circuit with one end opened to the atmosphere, a lubricant tank negative pressure circuit with one end communicating with the lubricant tank, the other end of the negative pressure source circuit, the other end of the outside air introduction circuit, and a lubricant tank negative pressure circuit The negative pressure introduction position that connects the negative pressure source circuit and the lubricating oil tank negative pressure circuit and the open air position that communicates the outside air introduction circuit and the lubricating oil tank negative pressure circuit are selectively interposed between the negative pressure source circuit and the lubricating oil tank negative pressure circuit. And a negative pressure circuit switching valve that switches repeatedly.

  According to the present invention, the lubricating oil tank pressure reducing means can be simply configured by the negative pressure source circuit, the outside air introduction circuit, the lubricating oil tank negative pressure circuit, and the negative pressure circuit switching valve. The lubricating oil tank pressure reducing means is formed when a lubricating oil tank pressure reducing circuit is formed in which the negative pressure source circuit and the lubricating oil tank negative pressure circuit communicate with each other while the negative pressure circuit switching valve is switched to the negative pressure introducing position. The pressure in the lubricating oil tank is reduced by the negative pressure of the intake pipe, the lubricating oil in the lubricating oil reservoir is sucked into the lubricating oil tank from the suction port through the lubricating oil suction circuit, and the negative pressure circuit switching valve is open to the atmosphere. When the lubricating oil tank atmosphere release circuit is formed in which the outside air introduction circuit and the lubricating oil tank negative pressure circuit communicate with each other, the inside of the lubricating oil tank is opened to the atmosphere, and the lubricating oil in the lubricating oil tank passes through the lubricating oil return circuit. Through the transmission case.

According to a fifth aspect of the present invention, in the lubricating structure for a vehicle transmission according to the fourth aspect, an atmospheric pressure sensor is provided, and the negative pressure circuit disconnection is detected when the atmospheric pressure sensor detects a low atmospheric pressure equal to or lower than a predetermined value. The valve is held in the open position to the atmosphere.

  According to the present invention, when the atmospheric pressure sensor detects an atmospheric pressure below a predetermined value at which the intake air negative pressure by the engine cannot be secured in a high altitude where the atmospheric pressure is relatively low, the operation of the negative pressure circuit switching valve is stopped. The unstable operation of the level adjusting device can be stopped and the influence on the engine performance can be avoided.

According to a sixth aspect of the present invention, there is provided a lubricating structure for a vehicle transmission according to the fourth or fifth aspect, further comprising a lubricating oil temperature sensor for detecting an oil temperature of the lubricating oil in the transmission case, wherein the lubricating oil temperature sensor is a predetermined value. The negative pressure circuit switching valve is held in the atmosphere open position when a low oil temperature below a value is detected.

  According to this invention, when the lubricating oil temperature sensor detects a low oil temperature below a predetermined value, the operation of the negative pressure circuit switching valve is stopped. Therefore, it is possible to avoid the noise that is generated when suctioning high lubricating oil from the suction port.

According to a seventh aspect of the present invention, in the lubricating structure for a vehicle transmission according to any one of the fourth to sixth aspects, the suction port is formed at a rear portion of the transmission case, and the vehicle body tilt is detected. A sensor is provided, and the negative pressure circuit switching valve is held in the atmosphere open position when the vehicle body tilt sensor detects a lean angle of the vehicle body lowering forward than a predetermined value.

  According to the present invention, when the vehicle body inclination sensor detects a forward downward inclination angle of the vehicle body greater than a predetermined value, the operation of the negative pressure circuit switching valve is stopped, so that air is sucked from the intake port during downhill traveling or the like. The generation of sound associated with can be avoided.

According to an eighth aspect of the present invention, in the lubricating structure for a vehicle transmission according to any one of the fourth to seventh aspects, an oil level sensor that detects an oil level of the lubricating oil stored in the lubricating oil reservoir is provided. And the negative pressure circuit switching valve is held in the atmosphere open position when the oil level sensor detects a low oil level position lower than the suction port.

  According to this invention, since the lubricating oil in the lubricating oil reservoir stops sucking from the suction port when the level of the lubricating oil in the lubricating oil reservoir is lower than the suction port, the oil level of the lubricating oil is maintained. It is done with high accuracy and speed. Further, when the oil level of the lubricating oil in the lubricating oil reservoir is lower than the suction port, air is not sucked from the suction port, and the sound generated by the suction of air can be suppressed.

  According to the present invention, there is provided a lubricating structure for a transmission for a vehicle including a transmission case in which a lubricating oil reservoir is formed and a gear having a rotatable lower end portion immersed in the lubricating oil stored in the lubricating oil reservoir. A suction port that opens to the transmission case in communication with the lubricating oil reservoir at a desired oil level of the lubricating oil stored in the lubricating oil reservoir, a lubricating oil tank, and a suction port and a lubricating oil tank; The lubricating oil suction circuit that communicates with each other, the lubricating oil return circuit that communicates between the lubricating oil tank and the transmission case, and the pressure reduction in the lubricating oil tank due to the negative pressure of the intake pipe of the engine and the opening of the lubricating oil tank to the atmosphere are repeated. Lubricating oil tank pressure reducing means, and the lubricant stored in the lubricating oil reservoir by repeatedly depressurizing the inside of the lubricating oil tank and releasing to the atmosphere by the lubricating oil tank pressure reducing means. Oil is sucked and stored in the lubricating oil tank from the suction port via the lubricating oil suction circuit, and the lubricating oil in the lubricating oil tank is returned to the transmission case via the lubricating oil return circuit. The oil level of the lubricating oil stored in the lubricating oil reservoir is maintained at the height of the suction port, so that the amount of immersion in which the lower end of the gear is immersed in the lubricating oil does not increase, and the stirring loss due to the stirring resistance of the gear Is suppressed.

  Hereinafter, an embodiment of a lubricating structure for a vehicle transmission according to the present invention will be described by taking a belt type continuously variable transmission as an example.

(First embodiment)
The first embodiment will be described with reference to FIGS. In each figure, an arrow F indicates the vehicle body front direction in the vehicle-mounted state, and an arrow W indicates the vehicle width direction.

  The transmission case 2 of the transmission 1 has a main case 10, a converter case 20 disposed on a side surface of the main case 10, and a side case (not shown), as schematically shown in FIG. An oil pan 30 made of sheet metal is attached to the lower surfaces of the main case 10 and the converter case 20.

  FIG. 2 is a cross-sectional view taken along the line II of FIG. 1 showing a side view of the main case 10. The main case 10 is integrally formed with a substantially cylindrical outer peripheral wall 11 that is continuous in the circumferential direction, and a partition wall 14 that divides the outer peripheral wall 11 into the transmission chamber 3 side and the power transmission mechanism chamber 4 side. That is, the cylindrical outer peripheral wall 11 is formed by the peripheral wall 12 protruding to one side along the outer periphery of the partition wall 14 and the peripheral wall 13 protruding to the other side. On the other hand, the converter case 20 has a cylindrical outer peripheral wall 23 that is continuous in the circumferential direction, and a side wall 24 that closes an end of the outer peripheral wall 23.

  A hollow transmission chamber 3 that accommodates the belt-type continuously variable transmission 31 by the main case 10 and the side case is formed by abutting and coupling the outer peripheral end of the side case to the top end surface of the peripheral wall 12 of the main case 10. It is formed. On the other hand, the power transmission mechanism chamber 4 is formed by abutting and joining the top end surface of the outer peripheral wall 23 of the converter case 20 to the peripheral wall 13.

  The power transmission mechanism chamber 4 is formed behind and below the forward / reverse switching mechanism chamber 5 that houses the forward / reverse switching mechanism 37, the speed reduction mechanism 45, and the like, and behind the forward / backward switching mechanism chamber 5, and accommodates the differential device 41. A bottom differential chamber 6 is integrally formed continuously.

  The belt-type continuously variable transmission 31 housed in the transmission chamber 3 is disposed in parallel in the front range and the upper range in the transmission chamber 3 as schematically shown by phantom lines in FIG. A primary shaft 32 that serves as an input shaft from the engine side and a secondary shaft 33 that serves as an output shaft, and a primary shaft 32 and a secondary shaft 33 that are rotatably spanned between the partition wall 14 and the side case of the main case 10. A primary pulley 34 and a secondary pulley 35 provided, and a drive belt 36 wound between the primary pulley 34 and the secondary pulley 35, and the pulley groove widths of the primary pulley 34 and the second pulley 35 are changed. By changing the ratio of the effective winding diameter of the drive belt 36 to the primary pulley 34 and the secondary pulley 35, the primer By shifting the input from the shaft 32 in a stepless and is configured to output to the secondary shaft 33.

  The forward / reverse switching mechanism 37 includes, for example, a planetary gear, a forward clutch, a reverse brake, and other frictional engagement elements arranged coaxially with the primary shaft 32, and is selectively operated by the forward clutch and the reverse brake. By controlling the operation of the planetary gear, the input rotational direction from the engine side is switched between forward and reverse, and transmitted to the primary shaft 32 of the continuously variable transmission 31. Since the forward / reverse switching mechanism 37 is not directly related to the present invention, detailed description thereof is omitted.

  The differential device 41 is disposed on the rear side of the vehicle body and below the forward / reverse switching mechanism 37, extends in the vehicle width direction, spans the partition wall 14 of the main case 10 and the side wall 24 of the converter case 20, and is freely rotatable. A hollow differential case 42 supported by the differential case 42, a final gear 43 integrally attached to the differential case 42, a pair of pinion gears rotatably supported on a pinion shaft (not shown) supported in the differential case 42, And a gear mechanism such as left and right side gears meshing with both pinion gears, and configured to transmit power from each side gear to the left and right wheels. In addition, the arrow attached | subjected to the differential case 42 has shown the rotation direction of the differential case 42 at the time of advance.

  The reduction mechanism 45 includes a drive gear 46 provided on the secondary shaft 33, a driven gear 47 that meshes with the drive gear 46, and a pinion gear 48 that meshes with the final gear 43 of the differential device 41. The driven gear 47 and the pinion gear 48 are reduced. The gear shaft 49 is integrally coupled, and is spanned between the partition wall 14 of the main case 10 and the side wall 24 of the converter case 20, and is rotatably supported.

  The peripheral wall 13 that protrudes from the outer periphery of the partition wall 14 of the main case 10 and forms the power transmission mechanism chamber 4 has a bottom surface portion 13A that continues in an arc along the lower portion of the differential device 51, and a differential that continues to the bottom surface portion 13A. A rear surface portion 13B that continues along the rear of the device 41 and the speed reduction mechanism 45, an upper surface portion 13C that continues to the rear surface portion 13B and continues along the upper side of the speed reduction mechanism 45 and the forward / reverse switching mechanism 37, and an upper surface portion 13C. The front surface portion 13D continuously extending downward along the front of the forward / reverse switching mechanism 37 and the weir forming portion that inclines so as to gradually rise as it moves forward continuously to the front end of the bottom surface portion 13A. 13E is continuously formed. A dam portion 13F protruding into the differential chamber 6 is formed in the vicinity of the upper end of the dam forming portion 13E.

  On the other hand, the cylindrical outer peripheral wall 16 continuously protruding in the circumferential direction from the side wall 24 of the converter case 20 includes a bottom surface portion 13A, a rear surface portion 13B, an upper surface portion 13C, a front surface portion 13D, which form the peripheral wall 13 of the main case 10. A bottom surface portion, a rear surface portion, an upper surface portion, a front surface portion, a dam formation portion, and a dam portion having respective top end portions that are abutted against the respective top end portions of the dam formation portion 13E and the dam portion 13F are continuously formed.

  The top end portions of the bottom surface portion 13A, the rear surface portion 13B, the top surface portion 13C, the front surface portion 13D, the weir forming portion 13E and the weir portion 13F that form the peripheral wall 13 of the main case 10 and the outer peripheral wall 16 of the converter case 15 are formed. The bottom surface portion, the rear surface portion, the top surface portion, the front surface portion, the weir forming portion, and the top end portions of the weir portion serve as mating surfaces that are brought into contact with each other when the main case 10 and the converter case 20 are coupled. In FIG. 2, a region that becomes a mating surface between the main case 10 and the converter case 20 is hatched.

  And the corresponding mating surface of the main case 10 and the mating surface of the converter case 20, that is, the bottom surface portion 13A, the rear surface portion 13B, the upper surface portion 13C, the front surface portion 13D, the weir forming portion 13E, and the peripheral wall 13 of the main case 10 Each top end portion of the weir portion 13F and the bottom end portion, the rear surface portion, the upper surface portion, the front surface portion, the weir formation portion, and the top end portions of the weir portion that form the outer peripheral wall 23 of the converter case 20 are brought into contact with each other, and fastening bolts (not shown) Thus, the forward / reverse switching mechanism chamber 5 that mainly accommodates the forward / reverse switching mechanism 37 and the speed reduction mechanism 45 and the differential chamber 6 that accommodates the differential mechanism 41 are continuously formed. A lubricating oil reservoir 7 is formed in the lower portion of the differential chamber 6.

  The lower end edge of the front surface portion 13D of the main case 10 serving as the lower end of the forward / reverse switching mechanism chamber 5, the upper end edge of the weir forming portion 13E, the lower end edge of the front portion of the converter case 20, the upper end edge of the weir forming portion, the converter case 20 A continuous oil pan alignment surface is formed by the lower end edge of the side wall part 24 and the lower end edge of the side wall part of the side case.

  In the transmission case 2 formed in this way, the power transmission mechanism chamber 4 and the oil pan 30 formed in a hollow shape continuous between the partition wall 14 of the main case 10 and the side wall 24 of the converter case 20 are moved forward and backward. Communication is performed below the switching chamber 5 through an opening 25 formed in a substantially rectangular shape.

  Further, an oil level adjusting device 50 is provided for adjusting the oil level L1 of the lubricating oil in the transmission case 2, particularly the lubricating oil in the lubricating oil reservoir 7.

  The oil level adjusting device 50 includes a suction port 51 that opens to a rear portion of the power transmission mechanism chamber 4 of the main case 10, for example, a rear portion of the bottom surface portion 13 </ b> A, and communicates with the lubricating oil reservoir portion 7. A lubricating oil tank 53 for storing lubricating oil supplied via 52, and a power transmission mechanism from an introduction hole that opens the lubricating oil stored in the lubricating oil tank 53 to an upper portion of the main case 10, for example, an upper surface portion 13C (not shown). A lubricating oil return circuit 54 to be introduced into the chamber 4 and a lubricating oil tank decompression means 60 for decompressing the inside of the lubricating oil tank 53 are provided.

Inlet 51 is bored in communication with the lubricating oil reservoir 7 to the transmission case 2 to the desired oil level height of lubricating oil stored in the lubricant reservoir 7 and one end to the suction port 51 connected The other end of the lubricating oil suction circuit 52 is connected to the upper portion 53 a of the lubricating oil tank 53. One end of the lubricating oil return circuit 54 is connected to the bottom 53 b of the lubricating oil tank 53, and the other end is connected to an inlet opening in the upper surface portion 13 </ b> C of the main case 10. In this lubricating oil return circuit 54, a filter 55 that removes impurities such as contaminants mixed in the lubricating oil in order from the lubricating oil tank 53 side and a check that allows the lubricating oil to flow from the lubricating oil tank 53 side to the main case 10 side. A valve 56 is interposed. In particular, the lubricating oil tank 53 is arranged at a higher position than the main case 10, and the lubricating oil in the lubricating oil tank 53 is configured to be able to flow from the inlet to the power transmission mechanism chamber 4 via the lubricating oil return circuit 54. .

  The lubrication tank pressure reducing means 60 has a negative pressure source circuit 62 connected at one end to the suction pipe of the engine E / G and connected at the other end to a negative pressure circuit switching valve 67 constituted by an electromagnetic three-way valve, and external air at one end. An outside air introduction circuit 64 in which the introduction port 64a is opened and opened to the atmosphere and the other end is connected to the negative pressure circuit switching valve 67, and one end is connected to the upper portion 53a of the lubricating oil tank 53 and the other end is a negative pressure circuit switching valve. A negative pressure circuit 61 having a lubricating oil tank negative pressure circuit 65 connected to 67 is provided. The outside air introduction port 64a of the outside air introduction circuit 64 is installed in an engine room or the like outside the transmission case 2 that is not wetted.

  A check valve 63 that allows air to flow from the negative pressure circuit switching valve 67 to the intake pipe side of the engine E / G is interposed in the negative pressure source circuit 62, and the lubricating oil is separated into the lubricating oil tank negative pressure circuit 65. A filter 66 having a gas permeable membrane 66a through which only air passes is interposed. The negative pressure circuit switching valve 67 is disposed higher than the upper portion 53 a of the lubricating oil tank 53, and is formed so that the lubricating oil adhering to the lubricating oil tank negative pressure circuit 65 flows down into the lubricating oil tank 53. ing.

  The negative pressure circuit switching valve 67 selectively switches between a negative pressure introduction position and an atmospheric release position. With the negative pressure circuit switching valve 67 switched to the negative pressure introduction position, the negative pressure source circuit 62 and the lubricating oil tank negative pressure circuit 65 communicate with each other and the inside of the lubricating oil tank 53 is caused by the intake pipe negative pressure of the engine E / G. A depressurizing lubricating oil tank pressure reducing circuit 61A is formed, and an open air introducing circuit 64 and a lubricating oil tank negative pressure circuit 65 communicate with each other at an open air position to form a lubricating oil tank open air circuit 61B that opens the inside of the lubricating oil tank 53 to the air. Is done.

  When the lubricating oil tank pressure reducing circuit 61A in which the negative pressure source circuit 62 and the lubricating oil tank negative pressure circuit 65 communicate with each other with the negative pressure circuit switching valve 67 switched to the negative pressure introducing position is formed, the engine E / G The inside of the lubricating oil tank 53 is depressurized by the negative pressure of the intake pipe, and the lubricating oil in the lubricating oil pool portion 7 is sucked into the lubricating oil tank 53 from the suction port 51 via the lubricating oil suction circuit 52, and then inside the lubricating oil tank 53. It is stored in. At this time, the check valve 56 interposed in the lubricating oil return circuit 54 is maintained in a closed state, and the lubricating oil and air in the power transmission mechanism chamber 4 are supplied to the lubricating oil tank 53 via the lubricating oil return circuit 54. Will not be introduced in.

  On the other hand, when the negative pressure circuit switching valve 67 is switched to the atmospheric release position to form the lubricating oil tank atmospheric release circuit 61B in which the outside air introduction circuit 64 and the lubricating oil tank negative pressure circuit 65 communicate with each other, the inside of the lubricating oil tank 53 is outside air. The introduction circuit 64 and the lubricating oil tank negative pressure circuit 65 release the air, and the lubricating oil in the lubricating oil tank 53 flows into the power transmission mechanism chamber 4 via the lubricating oil return circuit 54.

  FIG. 3 is a schematic explanatory diagram of a control device 70 for switching the negative pressure circuit switching valve 67 between a negative pressure introduction position and an atmospheric release position.

  The control device 70 includes a control unit 71, a pressure sensor 72 that detects negative pressure in the negative pressure source circuit 62, an atmospheric pressure sensor 73 that detects external air pressure, and a lubricating oil that detects the temperature of the lubricating oil in the transmission case 2. A temperature sensor 74, a vehicle body inclination sensor 75 for detecting the vehicle body inclination posture, an abnormality warning means, and a warning lamp 76 in the present embodiment are provided.

  When the pressure sensor 72 detects a negative pressure greater than or equal to a predetermined value in the negative pressure source circuit 62, that is, an operating state of the engine E / G in which the intake pipe of the engine E / G has a negative pressure, a negative pressure is detected by the control unit 71 according to the detection. The switching operation of the pressure circuit switching valve 67 between the negative pressure introduction position and the atmospheric release position is repeated.

  However, in the switching operation of the negative pressure circuit switching valve 67, the atmospheric pressure sensor 73 detects the atmospheric pressure below a predetermined value, for example, the low atmospheric pressure below the atmospheric pressure where the intake negative pressure by the engine E / G cannot be secured at high altitude or the like. Stops when detected. Similarly, when the lubricating oil temperature sensor 74 detects an oil temperature below a predetermined value, for example, a low oil temperature below a predetermined temperature with a high lubricating oil viscosity at the time of engine start or warm-up operation, and the vehicle body inclination sensor 75 The vehicle also stops when it detects a front-falling inclination angle of the vehicle body that is equal to or greater than a predetermined value, for example, a front-falling inclination angle of the vehicle body in a downhill traveling state that is greater than or equal to a predetermined inclination angle.

  Furthermore, when the so-called negative pressure circuit switching valve 67 does not switch regardless of an instruction from the control unit 71, when the so-called negative pressure circuit switching valve 67 is stuck and malfunctioned, the alarm lamp 76 is operated by the control unit 71 to inform the vehicle user or the like. Inform. For example, when the negative pressure circuit switching valve 67 is stuck between the negative pressure introduction position and the atmospheric release position, the external air introduction circuit 62 and the negative pressure source circuit 62 are not completely closed by the negative pressure circuit switching valve 67. The external communication state is maintained, the outside air is introduced from the outside air introduction circuit 62 to the negative pressure source circuit 62, and the negative pressure in the negative pressure source circuit 62 cannot be sufficiently obtained. Detected to detect a sticking failure of the negative pressure circuit switching valve 67. At this time, the check valve 63 interposed in the negative pressure source circuit 62 restricts the flow of air and functions as a so-called throttle to prevent excessive outside air from being introduced to the intake pipe side of the engine E / G. The effect on G performance is avoided.

  In the transmission 1 configured as described above, a control valve constituting a hydraulic circuit (not shown) is provided in the oil pan 30, and the control valve is provided with an oil pump from the oil pump to the oil pan 30 according to preset operation conditions. Lubricating oil is supplied and used as operating oil for various actuators such as actuator control of the continuously variable transmission 31 and forward clutch and reverse brake of the forward / reverse mechanism 37. The lubricating oil from the oil pump is supplied for lubricating each member. Thus, the lubricating oil used for lubrication and control of each part flows down along the inner wall surfaces of the main case 10 and the converter case 20, or is collected and recirculated in the oil pan 30 by a return pipe (not shown).

  Here, the engine E / G in the state where the rotation of the final gear 53 integrally coupled to the differential case 52 is stopped or the rotation speed is slow, such as when the vehicle stops on an almost horizontal road surface at an altitude of a predetermined value or less. In the operating state, the pressure sensor 72 of the control device 70 detects a negative pressure greater than or equal to a predetermined value, the atmospheric pressure detected by the atmospheric pressure sensor 73 is greater than or equal to a predetermined value, and the lubricant temperature detected by the lubricant temperature sensor 74 is When the vehicle body inclination sensor 75 detects the forward downward inclination angle detected by the vehicle body inclination sensor 75 is less than the predetermined value, the control unit 71 causes the negative pressure circuit switching valve 67 of the pressure reducing means 60 to move to the negative pressure introduction position and the atmospheric release position. Are continuously switched.

  When the negative pressure circuit switching valve 67 is at a negative pressure introduction position, a lubricating oil tank pressure reducing circuit 61A is formed in which the negative pressure source circuit 62 and the lubricating oil tank negative pressure circuit 65 communicate with each other, and lubrication is performed by the intake pipe negative pressure of the engine E / G. Lubricating oil stored in the lubricating oil reservoir 7 is decompressed and sucked into the lubricating oil tank 53 through the lubricating oil suction circuit 52 from the suction port 51 and stored therein. On the other hand, a lubricating oil tank atmosphere releasing circuit 61B in which the outside air introducing circuit 64 and the lubricating oil tank negative pressure circuit 65 communicate with each other is formed in the atmosphere releasing position of the negative pressure circuit switching valve 67, and the inside of the lubricating oil tank 53 is opened to the atmosphere and lubricated. The lubricating oil in the oil tank 53 is returned to the power transmission mechanism chamber 4 via the lubricating oil return circuit 54.

  Therefore, as shown in FIG. 2, the liquid level L1 of the lubricating oil stored in the lubricating oil reservoir 7 in the power transmission mechanism chamber 4 is held at the height of the suction port 51, that is, the desired oil level. The As a result, the desired amount of lubricating oil is ensured in the differential chamber 6 without excess or deficiency, and is scraped up by the final gear 43 and scraped off and scattered to the forward / reverse switching mechanism chamber 5 side. The switching mechanism 37 is lubricated without excess and deficiency, and the lubricating oil in the forward / reverse switching mechanism chamber 5 is returned to the oil pan 30 through the opening 25. Further, the lower end portion of the final gear 43 immersed in the lubricating oil, that is, the amount of stirring caused by the stirring resistance of the lubricating oil without increasing the amount of the lubricating oil swirled by the final gear 43 due to the viscosity of the lubricating oil being regulated. Is suppressed.

  And even if the amount of lubricating oil scraped up by the final gear 43 increases as the rotational speed of the final gear 43 increases, the liquid level L1 of the lubricating oil in the lubricating oil pool portion 7 is held at the height position of the suction port 51. Thus, lubrication of the speed reduction mechanism 45 and the forward / reverse switching mechanism 37 can be ensured. The lower end portion of the final gear 43 immersed in the lubricating oil, that is, the amount of immersion is regulated, and the amount of stirring of the lubricating oil by the final gear 43 due to the viscosity of the lubricating oil does not increase, and the stirring loss due to the stirring resistance of the lubricating oil increases. It is suppressed and fuel consumption improves.

  In addition, the lubricating oil stored in the lubricating oil reservoir 7 in the power transmission mechanism chamber 4 is also sucked in even during sudden acceleration or climbing when the lubricating oil in the transmission case 2 moves backward due to inertia or a change in the posture of the vehicle body. The oil level L1 of the lubricating oil in the lubricating oil reservoir 7 is prevented from rising by being drawn into the lubricating oil tank 53 from 51 through the lubricating oil suction circuit 52. Thereby, the immersion amount in which the lower end portion of the final gear 43 is immersed in the lubricating oil does not increase, the increase in the amount of the lubricating oil swung by the final gear 43 is prevented, and the loss due to the stirring resistance is suppressed.

  On the other hand, the load acting on the transmission changes according to the running state of the vehicle, and when the load during high speed driving is large, the amount of heat generated in the gear, bearing, shaft, etc. of the transmission 1 increases, Although the amount of lubricating oil increases as the temperature of the lubricating oil rises, the lubricating oil in the power transmission mechanism chamber 4 also enters the lubricating oil tank 53 from the suction port 51 via the lubricating oil suction circuit 52 in this case. As a result, the oil level L1 of the lubricating oil in the lubricating oil reservoir 7 is prevented from rising, the amount of immersion of the lower end portion of the final gear 43 in the lubricating oil does not increase, and the loss due to stirring resistance is suppressed.

  Further, even during downhill traveling in which the lubricating oil moves forward due to a change in the posture of the vehicle body, the movement of the lubricating oil from the differential chamber 6 side to the oil pan 30 side is restricted by the weir portion 13F as shown in FIG. At the same time, the oil surface L1 is regulated by the weir portion 13F to secure the lubricating oil stored in the lubricating oil reservoir portion 7, and the amount of immersion in which the lower end portion of the final gear 43 is immersed in the lubricating oil is ensured. Insufficient lubrication can be effectively avoided. Further, an increase in the amount of lubricating oil swung by the final gear 43 is prevented, and loss due to stirring resistance is suppressed.

  Here, in a downhill traveling state with a predetermined inclination angle or more, the suction port 51 may be positioned above the lubricating oil level L1 and air may be sucked from the suction port 51. However, the vehicle body tilt sensor 75 has a predetermined value. When the above-described leaning angle of the vehicle body is detected, the operation of the negative pressure circuit switching valve 67 is stopped and held in the atmospheric release position, thereby avoiding the intake noise generated when air is sucked from the suction port 51. can do.

  Similarly, at the time of deceleration in which the lubricating oil moves forward, the weir portion 13F restricts the movement of the lubricating oil from the differential chamber 6 side to the oil pan 30 side, and the oil surface L1 is restricted by the weir portion 13F to lubricate. Lubricating oil in the oil sump 7 is ensured, and a dipping amount in which the lower end portion of the final gear 43 is immersed in the lubricating oil is ensured, so that insufficient lubrication of the final gear 43 and the like can be effectively avoided, and the lubricating oil by the final gear 43 An increase in the amount of swirling is prevented, and loss due to stirring resistance is suppressed.

  On the other hand, when the rotation of the final gear 43 stopped from the running state is stopped or the rotation speed is extremely slow, the lubrication scattered or dropped from the forward / reverse switching mechanism 37, the differential device 41, and the speed reduction mechanism 45. Oil or lubricating oil that has flowed down along the inner wall surface such as the peripheral wall 13 of the main case 10, the partition wall 14, the outer peripheral wall 23 of the converter case 20, and the side wall 24 is accumulated in the lubricating oil reservoir 7 formed at the bottom of the differential chamber 6. Is done. The lubricating oil accumulated in the lubricating oil reservoir 7 retains the liquid level L1 at the height of the suction port 51, so that the final gear 43 and the like can be lubricated even when the vehicle is stopped or the final gear 43 rotates very slowly. It can be secured.

  Further, when the atmospheric pressure sensor 73 detects an atmospheric pressure below a predetermined value at which an intake negative pressure by the engine E / G cannot be ensured in a high altitude or the like where the atmospheric pressure is relatively low, the operation of the negative pressure circuit switching valve 67 is stopped to By holding in the open position, the unstable operation of the oil level adjusting device 50 is stopped, and generation of sound when the lubricating oil in the lubricating oil pool 7 is sucked from the suction port 51 is avoided. Moreover, the influence on engine E / G performance is avoided.

  When the lubricating oil temperature sensor 74 detects a low oil temperature below a predetermined value, the operation of the negative pressure circuit switching valve 67 is stopped. Thereby, generation | occurrence | production of the sound at the time of attracting | sucking from the inlet 51 lubricating oil with high viscosity at the time of low temperature, such as the time of start-up and a warming-up operation, can be avoided.

  Therefore, the lubricating oil in the power transmission mechanism chamber 4 is optimally maintained without excess or deficiency even in various operating conditions such as changes in the vehicle body posture, acceleration and deceleration, and changes in the temperature of the lubricating oil. Without increasing the amount of immersion of the lower end portion in the lubricating oil, an increase in the amount of lubricating oil swung by the final gear 43 is prevented, and the stirring loss is suppressed by the stirring resistance.

  Further, the lubricating oil is sucked into the lubricating oil tank 53 and the lubricating oil stored in the lubricating oil tank 53 is returned to the power transmitting chamber 4 by the intake pipe negative pressure of the engine E / G. Since the liquid level L1 of the lubricating oil stored in the lubricating oil reservoir 7 is controlled, a new driving means such as an electric motor is unnecessary, and the transmission 1 is increased in size, simplified in configuration, and increased in manufacturing cost. Can be suppressed.

(Second Embodiment)
A second embodiment will be described with reference to FIGS. FIG. 5 is a cross-sectional view of the transmission case corresponding to FIG. 2 of the first embodiment, and FIG. 6 is a schematic explanatory diagram of the control device. 5 and 6 are denoted by the same reference numerals as those in FIG. 1 to FIG. 4, and detailed description thereof is omitted.

  In the present embodiment, an oil level sensor 78 that detects the oil level L1 of the lubricating oil stored in the lubricating oil reservoir 7 of the power transmission mechanism chamber 4 is provided, and the oil level sensor 78 opens to the main case 2. In the state where the oil level L1 at the high oil level position exceeding the above is detected, the switching operation of the negative pressure circuit switching valve 67 between the negative pressure introduction position and the atmospheric release position is repeated, and the oil level L1 at the low oil level position is detected from the suction port 51. In this state, the negative pressure circuit switching valve 67 is configured to be held in the atmospheric release position.

  As shown in FIG. 6, the control device 70 includes a control unit 71, a pressure sensor 72, an atmospheric pressure sensor 73, a lubricant temperature sensor 74, a vehicle body inclination sensor 75, and a warning lamp 76, as in the first embodiment. Further, an oil level sensor 78 is provided.

  The pressure sensor 72 detects a negative pressure greater than or equal to a predetermined value in the negative pressure source 62, that is, the engine E / G in which the intake pipe of the engine E / G has a negative pressure, and the oil level sensor 78 detects the main case 2. In the state in which the oil level L1 at a high position exceeding the suction port 51 opened at the position is detected, the controller unit 71 repeatedly switches the negative pressure circuit switching valve 67 between the negative pressure introduction position and the atmospheric release position in accordance with the detection. .

  On the other hand, when the pressure sensor 72 detects a negative pressure of a predetermined value or more in the negative pressure source 62 and the oil level sensor 78 detects the oil level L1 at a lower oil level than the suction port 51, the controller unit 71 switches the pressure level. The operation is stopped, and the negative pressure circuit switching valve 67 is held at the atmospheric release position.

That is, the lubricating oil stored in the lubricating oil reservoir 7 when the liquid level L1 of the lubricating oil in the lubricating oil reservoir 7 is at a higher oil level than the suction port 51 passes through the lubricating oil suction circuit 52 from the suction port 51. Lubricating oil that is sucked and stored in the lubricating oil tank 53 and that the lubricating oil in the lubricating oil tank 53 returns to the power transmission mechanism chamber 4 via the lubricating oil return circuit 54 and is stored in the lubricating oil reservoir 7. lubricant oil level L1 is held at the height position of the suction port 51, the liquid level L1 of the lubricating oil of the power transmission mechanism chamber 4 is stored in the lubricant reservoir 7 when the lower position than the suction port 51 Stops the suction from the suction port 51 into the lubricating oil tank 53, and holds the liquid level L <b> 1 of the lubricating oil at the height position of the suction port 51.

  The switching operation of the negative pressure circuit switching valve 67 is performed when the atmospheric pressure sensor 73 detects an atmospheric pressure below a predetermined value, when the lubricating oil temperature sensor 74 detects an oil temperature below a predetermined value, and when the vehicle body tilts. The operation also stops when the sensor 75 detects a leaning angle of the vehicle body that is lower than the predetermined value.

  Therefore, as in the first embodiment, the lubricating oil in the lubricating oil pool portion 7 is optimal without any excess or deficiency even in various operating conditions such as changes in the body posture, acceleration and deceleration, and changes in the lubricating oil temperature. Thus, without increasing the amount of immersion of the lower end portion of the final gear 43 in the lubricating oil, an increase in the amount of the lubricating oil swung by the final gear 43 is prevented, and the stirring loss is suppressed by the stirring resistance.

  Furthermore, when the liquid level L1 of the lubricating oil in the lubricating oil pool portion 7 is lower than the suction port 51, the lubricating oil in the lubricating oil pool portion 7 stops suction from the suction port 51 into the lubricating oil tank 53. For this reason, the oil surface L1 of the lubricating oil is held with higher accuracy and speed.

  Furthermore, when the liquid level L1 of the lubricating oil in the lubricating oil pool portion 7 is at a lower oil level position than the suction port 51, air is not sucked from the suction port 51, and the sound generated by the suction of air is suppressed. it can.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. For example, although the lubricating oil tank 53 is formed separately from the transmission case 2 in the above embodiment, it can be formed integrally with the transmission case 2 or disposed in the transmission case 2. In addition, a check valve that allows the lubricant to flow from the lubricant reservoir 7 side to the lubricant tank 53 side may be interposed in the lubricant intake circuit 52. Further, in each of the above-described embodiments, a transmission having a belt-type continuously variable transmission has been described as an example. However, a lubricating structure for other transmissions such as a multi-stage automatic transmission using a planetary gear or a manual transmission is used. It can also be changed.

1 is a front view schematically showing a transmission case of a transmission showing an outline of a first embodiment of a lubricating structure for a vehicle transmission according to the present invention. It is the II sectional view taken on the line of FIG. 1 which shows the side view of a transmission case. It is a schematic explanatory drawing of a control apparatus. It is a side view of the transmission case at the time of downhill driving. It is sectional drawing of the transmission case which shows the outline | summary of 2nd Embodiment of the lubrication structure of the transmission for vehicles by this invention. It is a schematic explanatory drawing of a control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission 2 Transmission case 3 Transmission chamber 4 Power transmission mechanism chamber 5 Forward / reverse switching mechanism chamber 6 Differential chamber 7 Lubricating oil reservoir part 14 Partition 20 Converter case 23 Outer peripheral wall 24 Side wall 25 Opening part 30 Oil pan 31 Belt type continuously variable Transmission 37 Forward / reverse switching mechanism 41 Differential device 43 Final gear (gear)
50 Oil level adjusting device 51 Suction port 52 Lubricating oil suction circuit 53 Lubricating oil tank 53a Upper part 53b Lower part 54 Lubricating oil return circuit 56 Check valve 60 Lubricating oil tank pressure reducing means 61 Negative pressure circuit 61A Lubricating oil tank pressure reducing circuit 61B Lubricating oil tank Atmospheric release circuit 62 Negative pressure source circuit 63 Check valve 64 Outside air introduction circuit 65 Lubricating oil tank negative pressure circuit 67 Negative pressure circuit switching valve 70 Controller 71 Control unit 72 Pressure sensor 73 Atmospheric pressure sensor 74 Lubricating oil temperature sensor 75 Car body inclination Sensor 76 Warning lamp (Abnormal warning means)

Claims (8)

A transmission case in which a lubricating oil reservoir portion in which lubricating oil is stored is formed in the lower part of the interior, and a gear that is rotatably stored in the transmission case with its lower end portion immersed in the lubricating oil stored in the lubricating oil reservoir portion In a lubricating structure for a vehicle transmission provided with
A suction port that opens to the transmission case in communication with the lubricating oil reservoir at a desired oil level height position of the lubricating oil stored in the lubricating oil reservoir;
A lubricant tank,
A lubricating oil suction circuit communicating the suction port and the lubricating oil tank;
And the lubricating oil tank and the transmission case and the lubricating oil return circuit lubricating oil in the lubricating oil tank is communicated to be falling within the transmission case,
A lubricating structure for a vehicular transmission, comprising: a lubricating oil tank pressure reducing unit that repeatedly depressurizes the lubricating oil tank and releases the lubricating oil tank to the atmosphere by negative pressure of the intake pipe of the engine. A transmission chamber in the transmission case accommodates a transmission and a lubricating oil reservoir portion in which lubricating oil is stored in the lower portion is formed, and a lower end portion connected to the transmission so as to be able to transmit power is stored in the lubricating oil reservoir portion. In a lubricating structure for a vehicle transmission that is partitioned by a partition wall into a power transmission mechanism chamber that houses a differential device having a final gear immersed in lubricating oil,
A suction port that opens to the transmission case in communication with the lubricating oil reservoir at a desired oil level height position of the lubricating oil stored in the lubricating oil reservoir;
A lubricant tank,
A lubricating oil suction circuit communicating the suction port and the lubricating oil tank;
A lubricating oil return circuit that communicates between the lubricating oil tank and the power transmission mechanism chamber so that the lubricating oil in the lubricating oil tank can flow into the power transmission mechanism chamber ;
A lubricating structure for a vehicular transmission, comprising: a lubricating oil tank pressure reducing unit that repeatedly depressurizes the lubricating oil tank and releases the lubricating oil tank to the atmosphere by negative pressure of the intake pipe of the engine.   3. The lubricating of a vehicle transmission according to claim 1, wherein a check valve is provided in the lubricating oil return circuit to allow the lubricating oil to flow from the lubricating oil tank side to the transmission case side. Construction. The lubricating oil tank pressure reducing means is:
A negative pressure source circuit with one end communicating with the engine intake pipe,
An outside air introduction circuit having one end opened to the atmosphere;
A lubricating oil tank negative pressure circuit with one end communicating with the lubricating oil tank;
A negative pressure that is interposed between the other end of the negative pressure source circuit, the other end of the outside air introduction circuit, and the other end of the lubricating oil tank negative pressure circuit to communicate the negative pressure source circuit and the lubricating oil tank negative pressure circuit. 4. A negative pressure circuit switching valve that selectively and repeatedly switches to an atmosphere open position that communicates the introduction position and the outside air introduction circuit and the lubricating oil tank negative pressure circuit. 4. A lubricating structure for a vehicle transmission according to the item. 5. The vehicle gear shift according to claim 4, further comprising an atmospheric pressure sensor, wherein when the atmospheric pressure sensor detects a low atmospheric pressure that is equal to or lower than a predetermined value, the negative pressure circuit switching valve is held in an atmospheric release position. Machine lubrication structure. A lubricating oil temperature sensor for detecting the temperature of the lubricating oil in the transmission case is provided, and the negative pressure circuit switching valve is held in the open air position when the lubricating oil temperature sensor detects a low oil temperature below a predetermined value. The lubricating structure for a vehicle transmission according to claim 4 or 5, wherein The suction port is formed in the rear part of the transmission case,
A vehicle body inclination sensor for detecting a vehicle body inclination posture is provided, and the negative pressure circuit switching valve is held in the atmosphere open position when the vehicle body inclination sensor detects an inclination angle of the vehicle body lowering forward than a predetermined value. The lubricating structure for a vehicle transmission according to any one of claims 4 to 6. An oil level sensor for detecting an oil level of the lubricating oil stored in the lubricating oil reservoir, and when the oil level sensor detects a low oil level position lower than the suction port, the negative pressure circuit switching valve is opened to the atmosphere. The lubricating structure for a vehicle transmission according to any one of claims 4 to 7, wherein the lubricating structure is held in an open position.

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