Abstract:
A vehicle power transmission device including an accumulation portion which accumulates lubricating oil, a pressure pump driven to pump the lubricating oil accumulated in the accumulation portion to the transmission as hydraulic oil, a scooping gear which scoops up the lubricating oil accumulated in the accumulation portion while rotating, a reception and guide portion receiving the lubricating oil scooped up by the scooping gear and guiding it to a predetermined lubrication target, and a leaked hydraulic oil guide portion guiding leaked hydraulic oil, leaked when the hydraulic oil is pumped from the pressure pump, to the reception and guide portion.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The disclosure of Japanese Patent Application No. 2010-082491 filed on Mar. 31, 2010, including the specification, drawings and abstract thereof, is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a power transmission device. 
         [0004]    2. Description of the Related Art 
         [0005]    Heretofore, as this kind of power transmission device, one which includes a differential ring gear which rotates and thereby scoops up lubricating oil accumulated in a bottom portion in a transmission case, a catch tank which, as well as temporarily accumulating the lubricating oil, causes it to flow downward and supplies it to a counter drive gear and the like, a fluid introduction passage which introduces the lubricating oil scooped up by a differential ring gear disposed on an upper side in the case and supplies it to a lubrication and cooling pathway and the catch tank in the case, and an oil pump which is driven by a drive motor to supply the lubricating oil to each sliding and rolling portion in the case, has been proposed (for example, refer to JP-A-2009-250422). With this device, a lubrication of each lubrication target is carried out using the lubricating oil scooped up by the differential ring gear and the lubricating oil supplied by the oil pump. 
         [0006]    Also, a power transmission device which includes an oil pump which, being mounted between a pump housing and a pump cover which demarcates a first housing chamber housing a torque converter and a second housing chamber housing a planetary gear train of a transmission, supplies lubricating oil to the torque converter and the like as hydraulic oil, wherein a lubricating oil passage is formed in the pump housing, a lubricating oil supply port passing through the cover is formed in a position in the pump cover aligned with the lubricating oil passage, and a communication groove, which allows communication between the lubricating oil supply port and the clutch plate side of brakes which selectively fix rotational elements of the planetary gear train, is formed on a perimeter of the lubricating oil supply port, has also been proposed (for example, refer to JP-A-2007-85409). With the device, most of the oil is introduced into an oil passage connecting with the torque converter side, but one portion of the oil is drained to the lubricating oil passage and flows to the clutch plate side via the lubricating oil passage, lubricating oil supply port, and communication groove, thereby carrying out a lubrication of this clutch plate and the like. 
       SUMMARY OF THE INVENTION 
       [0007]    With the former power transmission device and a configuration that, as well as including a hydraulic transmission in addition to the former power transmission device, includes the oil pump of the latter device (an oil pump which, as well as pumping the hydraulic oil (lubricating oil) for operating the transmission, drains one portion of the lubricating oil and supplies it for lubrication) in place of the oil pump of the former device (an oil pump which pumps the lubricating oil for lubrication), when the lubricating oil pumped by the oil pump is large in amount, the lubricating oil scooped up by the differential ring gear decreases because the amount of lubricating oil accumulated in the case bottom portion decreases, and when the lubricating oil pumped by the oil pump is small in amount, the lubricating oil supplied from the oil pump for lubrication decreases. For this reason, a case in which a sufficient lubrication cannot be carried out with only the lubricating oil from one of these occurs depending on a member (a lubrication target). 
         [0008]    The power transmission device of the invention has a main object of preventing lubricating oil supplied to a predetermined lubrication target from running short. 
         [0009]    The power transmission device of the invention adopts the following mechanism in order to achieve the heretofore described main object. 
         [0010]    The gist of the power transmission device of the invention, being a power transmission device which, as well as being mounted in a vehicle, is housed in a casing, and includes a hydraulic transmission which transmits power from a motor to an axle, is that it includes: 
         [0011]    an accumulation portion which accumulates lubricating oil; 
         [0012]    a pressure pump which is driven by the motor to pump the lubricating oil accumulated in the accumulation portion to the transmission as hydraulic oil of the transmission; 
         [0013]    a scooping gear which scoops up the lubricating oil accumulated in the accumulation portion while rotating; 
         [0014]    a reception and guide portion which receives the lubricating oil scooped up by the scooping gear and guides it to a predetermined lubrication target; and 
         [0015]    a leaked hydraulic oil guide portion which guides leaked hydraulic oil, leaking when the hydraulic oil is pumped from the pressure pump, to the reception and guide portion. 
         [0016]    The power transmission device of the invention includes the scooping gear which scoops up the lubricating oil accumulated in the accumulation portion while rotating, the reception and guide portion which receives the lubricating oil scooped up by the scooping gear and guides it to the predetermined lubrication target, and the leaked hydraulic oil guide portion which guides the leaked hydraulic oil, leaking when the hydraulic oil is pumped from the pressure pump, to the reception and guide portion. Consequently, the lubricating oil scooped up by the scooping gear and the lubricating oil discharged from the pressure pump and guided by the leaked hydraulic oil guide portion are once gathered in the reception and guide portion, and guided to the predetermined lubrication target, meaning that it is possible to prevent the lubricating oil supplied to the predetermined lubrication target from running short even when either the lubricating oil scooped up by the scooping gear or the lubricating oil discharged from the pressure pump and guided by the leaked hydraulic oil guide portion is small in amount. Also, it is also possible to simplify the reception and guide portion in comparison with an arrangement wherein guide portions which guide the lubricating oil to the predetermined lubrication target are provided one for each of the lubricating oil scooped up by the scooping gear and the lubricating oil discharged from the pressure pump and guided by the leaked hydraulic oil guide portion. 
         [0017]    With the thus configured power transmission device of the invention, an arrangement can be such that a place of the reception and guide portion differing from a place which guides the leaked hydraulic oil to the predetermined target opens into the atmosphere. By so doing, when the lubricating oil gathered in the reception and guide portion is large in amount, one portion of the lubricating oil spills from the place opening into the atmosphere, meaning that it is possible to prevent excess lubricating oil from being supplied to the predetermined lubrication target. 
         [0018]    Also, with the power transmission device of the invention, an arrangement can be such that the reception and guide portion has a main body which temporarily accumulates the lubricating oil, an introduction portion which introduces the lubricating oil scooped up by the scooping gear to the main body, and a lubrication guide portion which guides the lubricating oil of the main body to the predetermined lubrication target. In this case, it is possible to achieve a further reduction in size of the main body. 
         [0019]    With the power transmission device of the aspect of the invention wherein the reception and guide portion has the main body, introduction portion, and lubricating guide portion, an arrangement can also be such that the introduction portion is formed in such a way as to decline toward the main body side. 
         [0020]    Also, with the power transmission device of the aspect of the invention wherein the reception and guide portion has the main body, introduction portion, and lubricating guide portion, an arrangement can be such that a shield is disposed between the scooping gear and predetermined lubrication target. In this case, it is difficult to directly supply the lubricating oil scooped up by the scooping gear to the predetermined lubrication target, meaning that it is significant to provide the reception and guide portion. With the power transmission device of the aspect of the invention, an arrangement can be such that the shield is a counter driven gear which, being attached to a counter shaft, meshes with a counter drive gear attached to an output shaft of the transmission, the scooping gear is a differential ring gear which, as well as meshing with a differential pinion gear attached to the counter shaft, is linked to a differential mechanism connected to the axle, and the predetermined lubrication target is a bearing which rotatably supports the counter shaft. With the power transmission device of the aspect of the invention, an arrangement can also be such that the main body is disposed on the side opposite to the differential ring gear across the counter driven gear, and the lubrication guide portion is formed along an inner wall surface of the casing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a configuration diagram showing an outline of a configuration of a power transmission device  20  as one embodiment of the invention; 
           [0022]      FIG. 2  is an illustration showing a condition of a disposition in a casing  21 ; 
           [0023]      FIG. 3  is a fragmentary sectional view showing an A-A partial cross-section of  FIG. 2 ; 
           [0024]      FIG. 4  is a fragmentary sectional view showing a B-B partial cross-section of  FIG. 2 ; and 
           [0025]      FIG. 5  is an illustration showing one example of a catch tank  180  of a modification example. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0026]    Next, a description will be given, using an embodiment, of a best mode for carrying out the invention. 
         [0027]      FIG. 1  is a configuration diagram showing an outline of a configuration of a power transmission device  20  as one embodiment of the invention. The power transmission device  20  of the embodiment is configured as a transaxle device which, being mounted on an automobile  10 , changes the speed of power from an engine  12  and transmits the power to left and right front wheels  18   a  and  18   b , and as shown in the drawing, includes a lockup clutch equipped torque converter  22  which has an input side pump impeller  23  connected to a crankshaft  14  of the engine  12  and an output side turbine runner  24 , an oil pump  30  which, being disposed in the subsequent stage of the torque converter  22 , is driven by the engine  12  to pump hydraulic oil (lubricating oil), a hydraulic multistage automatic transmission  40  which, having an input shaft  41  connected to the turbine runner  24  of the torque converter  22  and an output shaft  42 , changes the speed of the power input into the input shaft  41  and outputs the power to the output shaft  42 , a hydraulic circuit  50  which receives a supply of the hydraulic oil from the oil pump  30  and supplies the hydraulic oil to the torque converter  22  (lockup clutch) or the automatic transmission  40  (clutches and brakes) as necessary, a gear mechanism  60  which, as well as being connected to the output shaft  42  of the automatic transmission  40 , is connected via a differential mechanism (a differential gear)  70  to axles  19   a  and  19   b  linked to the front wheels  18   a  and  18   b , and a casing (refer to  FIG. 2 ) which houses these. 
         [0028]    The oil pump  30  is configured as a so-called gear pump having a pump assembly  31  formed of a pump body  32  fixed to the casing  21  (refer to  FIG. 2 ) and a pump cover  34 , and an externally toothed gear  35  disposed in the pump assembly  31 . Herein, the externally toothed gear  35 , being connected to the pump impeller  23  via a hub  25 , forms a crescent together with unshown internal teeth formed on the pump body  32 . Also, a discharge oil passage  33  (refer to  FIGS. 2 and 4 ) which discharges the lubricating oil is formed in the pump body  32 . The outer periphery of the hub  25  and the inner periphery of the pump body  32  are sealed with an oil seal  36 , preventing a leakage of the lubricating oil (a discharge of the lubricating oil from other than the discharge oil passage  33 ). The thus configured oil pump  30 , on the externally toothed gear  35  rotating with the power from the engine  12 , suctions the lubricating oil accumulated in the bottom portion (hereafter referred to as an accumulation portion  21   a ) of the casing  21  and, as well as pumping most of the lubricating oil to an oil passage (not shown) connecting with the hydraulic circuit  50  as the hydraulic oil of the hydraulic circuit  50 , discharges one portion (leaked hydraulic oil leaking from the oil passage connecting with the hydraulic circuit  50 ) of the lubricating oil through the discharge oil passage  33  via the lubrication of the oil seal  36 . In the examples of  FIGS. 2 and 4 , the discharge oil passage  33  is formed in such a way that the lubricating oil moves obliquely upward and is discharged, but as the lubricating oil is pumped by the externally toothed gear  35  rotating, it is possible to discharge the leaked hydraulic oil through the discharge oil passage  33 . 
         [0029]    The automatic transmission  40  is configured as a four-staged transmission which can switch between forward first to fourth speeds, reverse, and neutral by changing an engagement condition (the activation or deactivation) of the plurality of clutches and brakes. Herein, the activation or deactivation of the clutches and brakes is carried out by an oil pressure caused to act on the clutches and brakes being adjusted by the operation of the hydraulic circuit  50 . 
         [0030]    The gear mechanism  60  includes a counter drive gear  61  attached to the output shaft  42  of the automatic transmission  40 , a counter driven gear  63  which, being attached to a counter shaft  62  disposed parallel to the output shaft  42 , meshes with the counter drive gear  61 , a differential pinion gear (a final drive gear)  64  attached to the same counter shaft  62 , and a differential ring gear (a final driven gear)  65  which, as well as meshing with the differential pinion gear  64 , is linked to the differential mechanism (differential gear)  70 . 
         [0031]    The differential mechanism  70 , being configured as a known differential gear, includes a differential case  71  which, being rotatably supported in the casing  21 , is linked to the differential ring gear  65 , an unshown pair of pinion mate gears (bevel gears) fixed to a shaft rotatably supported on the differential case  71 , and an unshown pair of side gears meshing one with either pinion mate gear, and the axles  19   a  and  19   b  linked to the front wheels  18   a  and  18   b  are connected one to either side gear. 
         [0032]      FIG. 2  is an illustration showing a condition of a disposition in the casing  21 ,  FIG. 3  is a fragmentary sectional view showing an A-A partial cross-section of  FIG. 2 , and  FIG. 4  is a fragmentary sectional view showing a B-B partial cross-section of  FIG. 2 . In  FIG. 2 , the solid arrows show the rotation directions of the counter driven gear  63  and differential ring gear  65  when travelling forward, and in  FIGS. 2 to 4 , the dashed arrows show the flows of the lubricating oil. The differential ring gear  65  is disposed in a position in the casing  21  on the lower left side in the drawing in such a way that some of the external teeth thereof are immersed in the lubricating oil accumulated in the accumulation portion  21   a  (hereafter, this lubricating oil will be referred to as the accumulated oil), as shown in  FIG. 2 , and rotates clockwise in the drawing when travelling forward. Consequently, when travelling forward, the accumulated oil is scooped upward along the inner wall surface of the casing  21  by the rotation of the differential ring gear  65  (refer to the dashed arrows in the drawing). The inner wall surface of the casing  21  is formed to be approximately smooth in such a way that the accumulated oil is easily scooped upward by the differential ring gear  65 . Also, in the example of  FIG. 2 , the lubricating oil around the counter driven gear  63  is also scooped upward by the rotation of the counter driven gear  63  rotating counterclockwise. 
         [0033]    As shown in  FIG. 3 , a catch tank  80  which, being formed on the upper left side in the drawing (the upper right side in  FIG. 2 ) of the counter driven gear  63  in such a way that a bottom portion  80   a  declines toward the inner wall surface side (the left side in the drawing) of the casing  21 , can temporarily accumulate the lubricating oil, is provided in the casing  21 , and on the lower left side in the drawing of the catch tank  80 , a clearance (hereafter referred to as an oil passage)  82  which guides the lubricating oil by gravity from the catch tank  80  to a bearing  62   a  which rotatably supports the counter shaft  62  is formed along the inner wall surface of the casing  21 . Consequently, the lubricating oil of the catch tank  80  flows to the left side in  FIG. 3 , moves by gravity down the oil passage  82 , and is supplied to the bearing  62   a . The lubricating oil supplied to the bearing  62   a  further moves downward by gravity, and returns to the accumulation portion  21   a  (refer to  FIG. 2 ). Also, the catch tank  80  is arranged so that the top, which is a place differing from the oil passage  82  side, opens into the atmosphere. Consequently, when the lubricating oil supplied to the catch tank  80  is large in amount, it happens that one portion of the lubricating oil overspills from the catch tank  80 . Furthermore, a portion (hereafter referred to as a ceiling portion)  21   b  of the casing  21  positioned above the differential ring gear  65  is formed in such a way as to decline toward the catch tank  80  side (the left side in the drawing). Consequently, the lubricating oil which has arrived at the ceiling portion  21   b  by being scooped up by the differential ring gear  65  and counter driven gear  63 , is supplied to the catch tank  80  by moving down the ceiling portion  21   b  to the catch tank  80  side and dropping by gravity. In addition, as shown in  FIGS. 3 and 4 , an oil passage  84  which allows communication between a position aligned with the discharge oil passage  33  of the oil pump  30  and a position above the catch tank  80  is formed in the casing  21 . Consequently, the leaked hydraulic oil (lubricating oil) discharged through the discharge oil passage  33  is supplied to the catch tank  80  through the oil passage  84 . The higher the rotational speed of the externally toothed gear  35  is (the larger the amount of hydraulic oil pumped is), the more the leaked hydraulic oil passing through the oil passage  84 . 
         [0034]    With the thus configured power transmission device  20  of the embodiment, as the hydraulic oil (lubricating oil) pumped by the oil pump  30  increases when the rotational speed of the engine  12  is high, the lubricating oil accumulated in the accumulation portion  21   a  decreases (the oil level lowers), and the lubricating oil scooped up by the differential ring gear  65  is likely to decrease, but the leaked hydraulic oil (hereafter referred to as the discharged and supplied oil) discharged through the discharge oil passage  33  of the oil pump  30  and supplied to the catch tank  80  via the oil passage  84  increases. Meanwhile, when the rotational speed of the engine  12  is low, the discharged and supplied oil decreases by an amount by which the hydraulic oil pumped by the oil pump  30  decreases, but the lubricating oil accumulated in the accumulation portion  21   a  increases (the oil level rises), and the lubricating oil (hereafter referred to as the differential gear scooped arriving oil) arriving at the catch tank  80  via the ceiling portion  21   b  by being scooped up by the differential ring gear  65  is likely to increase. Consequently, even when either the discharged and supplied oil or the differential gear scooped arriving oil is small in amount, a certain amount of lubricating oil is supplied to the catch tank  80  as a total amount of the discharged and supplied oil, the differential gear scooped arriving oil, and the lubricating oil arriving at the catch tank  80  via the ceiling portion  21   b  by being scooped up by the counter drive gear  63 , meaning that it is possible to prevent the lubricating oil supplied to the bearing  62   a  from running short. Moreover, as the leaked hydraulic oil (lubricating oil) discharged from the oil pump  30  and guided by the oil passage  84  and the lubricating oil scooped up by the differential ring gear  65  and counter driven gear  63  are once gathered in the catch tank  80 , and supplied to the bearing  62   a  via the oil passage  82 , it is possible to simplify the oil passage  82  in comparison with an arrangement wherein oil passages which guide these lubricating oils to the bearing  62   a  are formed one for each oil. Furthermore, as an arrangement is such that the top of the catch tank  80  opens into the atmosphere, one portion of the lubricating oil overspills from the catch tank  80  when the discharged and supplied oil or scooped arriving oil is large in amount, meaning that it is possible to prevent the lubricating oil from being excessively supplied to the bearing  62   a . Moreover, as the leaked hydraulic oil (lubricating oil) discharged from the oil pump  30  is once supplied to the catch tank  80  (whose top opens into the atmosphere) via the oil passage  84 , it is possible to prevent the leaked hydraulic oil from being excessively accumulated in the oil passage  84 , and it is possible to prevent a large pressure from acting on the oil seal  82  and oil passage  84 . In addition, with the configuration of the power transmission device  20  of the embodiment, as the counter driven gear  63  is disposed between the differential ring gear  65  and bearing  62   a , it is difficult to directly supply the bearing  62   a  with the lubricating oil scooped up by the differential ring gear  65 , but owing to the existence of the ceiling portion  21   b , catch tank  80 , and oil passage  82 , it is possible to supply the lubricating oil scooped up by the differential ring gear  65  to the bearing  62   a  via the ceiling portion  21   b , catch tank  80 , and oil passage  82 . 
         [0035]    According to the heretofore described power transmission device  20  of the embodiment, as there is provided the catch tank  80 , the oil passage  82  which supplies the lubricating oil of the catch tank  80  to the bearing  62   a , the ceiling portion  21   b  which receives the lubricating oil scooped up by the differential ring gear  65  and guides it to the catch tank  80 , and the oil passage  84  which guides the leaked hydraulic oil (lubricating oil), discharged from the oil pump  30 , to the catch tank  80 , it is possible to prevent the lubricating oil supplied to the bearing  62   a  from running short even when either the lubricating oil arriving at the catch tank  80  via the ceiling portion  21   b  by being scooped up by the differential ring gear  65 , or the leaked hydraulic oil (lubricating oil) discharged from the oil pump  30  and guided to the catch tank  80  by the oil passage  84 , is small in amount. Moreover, as the lubricating oil discharged from the oil pump  30  and guided by the oil passage  84  and the lubricating oil scooped up by the differential ring gear  65  are once gathered in the catch tank  80  and then supplied to the bearing  62   a  via the oil passage  82 , it is possible to simplify the oil passage  84  in comparison with an arrangement wherein oil passages are formed one for each of the two oils in such a way that the two oils are guided to the bearing  62   a.    
         [0036]    With the power transmission device  20  of the embodiment, an arrangement is such that the ceiling portion  21   b  of the casing  21  is formed in such a way as to decline toward the catch tank  80  side, but an arrangement may be such that, in addition to or in place of this, a catch tank is formed in such a way as to be able to receive the lubricating oil scooped up by the differential ring gear  65 . In this case, an arrangement may be such that a bottom portion  180   a  of a catch tank  180  is formed to have a width such as to be able to receive the lubricating oil scooped up by the differential ring gear  65 , as illustrated in  FIG. 5 . 
         [0037]    With the power transmission device  20  of the embodiment, an arrangement is such that the leaked hydraulic oil (lubricating oil) discharged from the oil pump  30  and guided by the oil passage  84  and the lubricating oil scooped up by the differential ring gear  65  and counter driven gear  63  are once gathered in the catch tank  80 , but an arrangement may be such that the lubricating oil scooped up by the counter driven gear  63  is not gathered in the catch tank  80 . 
         [0038]    With the power transmission device  20  of the embodiment, an arrangement is such that the catch tank  80  and the oil passage  82  (the clearance formed along the inner wall surface of the casing  21 ) are formed separately, but an arrangement may be such that they are integrally formed. 
         [0039]    With the power transmission device  20  of the embodiment, an arrangement is such that the lubricating oil of the catch tank  80  is supplied to the bearing  62   a  via the oil passage  82 , but an arrangement may be such that the lubricating oil is supplied to not only the bearing  62   a , but any member (lubrication target) such as a bearing other than the bearing  62   a , any gear, or any shaft. 
         [0040]    With the power transmission device  20  of the embodiment, an arrangement is such that it includes the four-speed automatic transmission  40  which can switch between the forward first speed to fourth speed, reverse, and neutral, but it being sufficient to include a hydraulic transmission, an arrangement may be such as to include a transmission with any number of speeds such as five speeds, six speeds, or eight speeds, and an arrangement may be such as to include a continuously variable transmission. 
         [0041]    A description will be given of a correspondence relationship between the main elements of the embodiment and the main elements of the invention described in the section of the disclosure of the invention. In the embodiment, the automatic transmission  40  corresponds to a “transmission”, the accumulation portion  21   a  of the casing  21  to an “accumulation portion”, the oil pump  30  to a “pressure pump”, the gear mechanism  60  having the differential ring gear  65   a  to a “gear mechanism”, the ceiling portion  21   b  of the casing  21 , the catch tank  80 , and the oil passage  82  to a “reception and guide portion”, and the oil passage  84  to a “leaked hydraulic oil guide portion”. 
         [0042]    As the correspondence relationship between the main elements of the embodiment and the main elements of the invention described in the section of the disclosure of the invention is one example for the embodiment to specifically describe the mode for carrying out the invention described in the section of the disclosure of the invention, it does not limit the elements of the invention described in the section of the disclosure of the invention. That is, the interpretation of the invention described in the section of the disclosure of the invention should be made based on the description of the section, and the embodiment is only one specific example of the invention described in the section of the disclosure of the invention. 
         [0043]    A description has heretofore been given, using the embodiment, of the mode for carrying out the invention but, the invention not being limited to this kind of embodiment in any way, it goes without saying that the invention can be carried out in various modes without departing from the scope thereof. 
         [0044]    The invention can be utilized by a power transmission device manufacturing industry and the like.