Abstract:
In an oil cooler installation structure for a vehicular transmission, an oil coolerby means of which oil is cooled is provided, oil being delivered between the oil cooler and an internal of a transmission housing, and an oil cooler installation portion is provided in the internal of the transmission housing and in which a first oil passage for supplying oil in the internal of the transmission housing to the oil cooler via a first opening portion opened at an external of the transmission housing and a second oil passage for supplying oil from the oil cooler to the internal of the transmission housing via a second opening portionpened at the external of the transmission housing are formed, the oil cooler being attached onto the oil cooler installation portion to enable a delivery of oil via the first opening portion and the second opening portion.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to an installation structure of an oil cooler of a vehicular transmission which carries out a delivery of an oil between the transmission and the oil cooler.  
         [0002]     Such a kind of technique as described above is disclosed in a Japanese Patent Application First Publication No. Heisei 6-108845 published on Apr. 19, 1994. In the above-described Japanese Patent Application First Publication No. Heisei 6-108845, the oil cooler is installed in a proximity to a radiator which is remote from the transmission, an oil feed pipe is interlinked between the transmission and the oil cooler, and an oil cooling is carried out with a coolant supplied from the radiator to an engine, and the cooled oil is supplied to the transmission via the oil feed pipe.  
       SUMMARY OF THE INVENTION  
       [0003]     However, since, in the above-described technique, the oil feed pipe is installed between the oil cooler and the transmission housing, it is necessary to secure a piping space within a narrow engine compartment. In addition, at least four of connecting portions among the oil feed pipe, the oil cooler, and a transmission housing are needed. Furthermore, a secured linkage to prevent an oil leakage from linkage portions of the oil feed pipe and its confirmation are needed. Consequently, problems of a worsening of the workability during the assembly of the oil cooler and an introduction of an increase in a working labor hour are raised.  
         [0004]     It is, therefore, an object of the present invention to provide an installation structure of an oil cooler of a vehicular transmission which is capable of reducing the piping space to deliver the oil, reducing the oil cooler installation labor hour, and improving a workability.  
         [0005]     According to one aspect of the present invention, there is provided with an oil cooler installation structure for a vehicular transmission, comprising: an oil cooler by means of which oil is cooled; an internal of a transmission housing in which a gear shift mechanism is housed, oil being delivered between the oil cooler and the internal of the transmission housing; and an oil cooler installation portion provided in the internal of the transmission housing and in which a first oil passage for supplying oil in the internal of the transmission housing to the oil cooler via a first opening portion opened at an external of the transmission housing and a second oil passage for supplying oil from the oil cooler to the internal of the transmission housing via a second opening portion opened at the external of the transmission housing are formed, the oil cooler being attached onto the oil cooler installation portion to enable a delivery of oil via the first opening portion and the second opening portion.  
         [0006]     This summary of the invention does not necessarily describe all necessary features so that the present invention may also be a sub-combination of these described features.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a schematic cross sectional view of an automatic transmission to which an installation structure of an oil cooler of a vehicular transmission in a preferred embodiment according to the present invention is applicable.  
         [0008]      FIG. 2  is a schematic view of a second housing of a transmission housing viewed from a first housing thereof for explaining the installation structure of the oil cooler in the preferred embodiment according to the present invention.  
         [0009]      FIG. 3  is a schematic view of the second housing viewed from a third housing for explaining the installation structure of the oil cooler in the preferred embodiment according to the present invention.  
         [0010]      FIG. 4  is a schematic view of the second housing viewed from a vehicular forward side when it is actually mounted in the vehicle for explaining the installation structure of the oil cooler in the preferred embodiment according to the present invention.  
         [0011]      FIG. 5  is an expanded view of an oil cooler installation portion for explaining the installation structure of the oil cooler in the preferred embodiment according to the present invention.  
         [0012]      FIG. 6  is a cross sectional view of the oil cooler installation portion for explaining the installation structure of the oil cooler in the preferred embodiment according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     Reference will hereinafter be made to the drawings in order to facilitate a better understanding of the present invention.  
         [0014]      FIG. 1  shows a rough cross sectional view of an automatic transmission to which an oil cooler installation structure of in a preferred embodiment according to the present invention is applicable. A transmission housing  100  includes a first housing  110 , a second housing  120 , and a third housing  130 . Within transmission housing  100 , a torque converter  200  to amplify a torque from an engine, a forward-and-backward (run) switching mechanism  300  having a start (forward) clutch, a belt type continuously variable transmission  400  which continuously variably transmits the input torque to output torque between input and output thereof, an idler gear  500 , and a differential gear  600 . In addition, a mechanism to supply a pressurized oil and a lubricating oil to each device includes: an oil strainer  710 , a control valve unit  720 , and an oil cooler  730  (refer to  FIG. 2 ). It is noted that torque converter  200 , forward-and-backward switching mechanism  300 , belt type continuously variable transmission  400 , idler gear  500 , and a differential gear  600  correspond to a gear shift mechanism according to the present invention.  
         [0015]     Torque converter  200  is constituted by a pump impeller connected to an engine output axle  10 , a turbine runner connected to a transmission input axle  20 , a stator to arrange a flow of an internal working oil, and a lock-up clutch to directly transmit a power to driven wheels during a high speed travel of the vehicle.  
         [0016]     Forward-and-backward switching mechanism  300  is constituted by a planetary gear mechanism having a sun gear linked to the engine and having the forward clutch, a carrier linked to a backward brake, a ring gear linked to a primary pulley  410  and having a forward clutch. It is noted that planetary gear mechanism may be a single pinion type or double pinion type planetary gear or any arbitrary planetary gear.  
         [0017]     Belt type continuously variable transmission  400  is constituted by a primary pulley  410  which is revolved in a unit with a revolution inputted from forward-and-backward switching mechanism  300  (movable pulley  410   a  and a stationary pulley  410   b ), a secondary pulley  420  (movable pulley  420   a  and stationary pulley  420   b ) revolved in a unit with the driven wheels at a predetermined speed reduction ratio, and a belt  430  wound over a groove of each pulley. An output gear  40  is fixed onto an end portion of a secondary pulley axle  30  installed on secondary pulley  30 .  
         [0018]     Two pinions of differential gear  600  are fixed on idler gear  500  and side gears are meshed with these pinions from left and right sides. A drive shaft is linked to each side gear and left and right driven wheels are driven by means of the drive shafts.  
         [0019]     Vane pump  700  is constituted by a rotor, a cam ring eccentrically attached to this rotor, and a vane to partition an oil chamber defined by the rotor and the cam ring. The vane is fitted into a groove of the rotor and, at its inner side, the working oil supplied to the center axle of the rotor and an oil passage installed on each groove presses the vane toward a cam ring due to a centrifugal force acted during the revolution of rotor. This structure can reduce the number of parts and can improve a life as compared with a case where the vane presses the spring on the cam ring. An end of the rotor toward torque converter  200  is fixed with a driven sprocket  701  and is linked to a drive sprocket  50  which is revolved in a unit with an input axle  20  of transmission  100  via a chain  51 .  
         [0020]     An oil strainer  710  is installed at a suction inlet side of a vane pump  700  and a control valve unit  720  is installed at a drainage outlet side of vane pump  700 . Electronic parts  721  such as a plurality of electromagnetic control valves and various types of sensors (oil temperature sensors and liquid pressure sensors) are disposed on an upper surface of control valve unit  720 .  
         [0021]     A coolant chamber to which a coolant is supplied and a lubricating oil chamber to which the lubricating oil is supplied are adjoined to one another and constructed in a laminated form, alternately, within an internal of oil cooler  730 . The coolant chamber of oil cooler  730  is connected with a water feed water passage  731  for the cooling water from oil cooler  730  to be supplied to the engine and with a supply water passage  732  to which the coolant cooled by means of the radiator is supplied. In addition, the lubricating oil chamber of oil cooler  730  is connected with a supply oil passage  123  to which a high temperature lubricating oil is supplied and with an exhaust oil passage  124  to exhaust the lubricating oil exhausted via oil filter  750  as will be described later. It is noted that supply oil passage  123  and exhaust oil passage  124  correspond to a first oil passage and a second oil passage, respectively, in the case of the present invention.  
         [0022]     Supply oil passage  123  is formed within second housing  120  and communicates with control valve unit  720 , an oil pan  740 , and an oil cooler  730 . In addition, exhaust oil passage  124  is similarly formed within second housing  120  and is communicated with each device of belt type continuously variable transmission  400 .  
         [0023]     [Arrangement of Each Device within Transmission Housing] 
         [0024]      FIG. 2  shows a rough view of second housing viewed from first housing  110 ,  FIG. 3  shows a rough view of second housing  120  viewed from third housing  130 , and  FIG. 4  shows a rough view of second housing  120  viewed from the forward direction of second housing shown in  FIGS. 2 and 3 . In  FIGS. 2 and 3 , belt type continuously variable transmission  400 , idler gear  500 , differential gear  600 , vane pump  700  are schematically represented by circles. In addition, circles denoted by broken lines in  FIGS. 2 and 3  are housed with a wall partitioned at the opposite side thereof.  
         [0025]     As shown in  FIG. 2 , belt type continuously variable transmission  400  is housed within a first housing chamber  121 . Primary pulley  410  of belt type continuously variable transmission  400  is housed on a lower part of a front side of first housing chamber  121 . A secondary pulley  420  is housed on an upper part of a rear side of first housing chamber  121 . In addition, a lower part of fist housing  121  is opened and a lubricating oil lubricated for each device is exhausted from this opening portion to oil pan  740 .  
         [0026]     Control valve unit  720  and electronic parts  721  are housed within a third housing chamber  129  projected toward a front side of second housing  120 . Third housing chamber  129  is formed with a harness inserting hole  126  into which harness to be connected to electronic parts  721  is inserted is formed. It is noted that third housing chamber  129  corresponds to a control valve unit housing portion according to the present invention.  
         [0027]     A plurality of check oil passages  127  to supply the pressurized oil to a tester  60  to perform a check in the hydraulic pressure developed in control valve unit  720  during a product check are formed. A plurality of check oil passages  127  (third oil passages) are mutually adjacently formed and, furthermore, supply oil passages  123  and exhaust oil passage  124  are adjacently formed to check oil passages  127 . Opening portions at control valve unit  720  side to check oil passage  127 , supply oil passage  123 , and exhaust oil passage  124  are precisely worked by means of a post working to maintain a liquid sealing ability between these oil passages and control valve unit  720 . It is noted that check oil passage  127  corresponds to a third oil passage according to the present invention.  
         [0028]     An oil cooler installation portion  122  on which oil cooler  730  is installed is integrally formed with second housing  120  on an upper portion of third housing portion  129  and check oil passage  127 . Oil cooler installation portion  122  is formed on the upper portion toward which third housing  129  is projected, as shown in  FIGS. 2 and 4 . In addition, oil cooler installation portion  122  is arranged at the radiator side when second housing  120  is mounted on the vehicle in order to shorten the piping between a supply water passage  731  to supply the coolant and the radiator.  
         [0029]     A revolution speed sensor inserting hole  125  into which a revolution sensor for primary pulley  410  is inserted is formed between third housing portion  129  and oil cooler installation portion  122 .  
         [0030]     As described above, the parts related to control valve unit  720  are concentrated and arranged at the lower portion and the parts related to oil cooler  730  are concentrated and arranged at the upper portion.  
         [0031]     At torque converter  200 , idler gear  500 , differential gear  600 , and vane pump  700  are housed in second housing portion  128 , as shown in  FIG. 3 .  
         [0032]     Differential gear  600  is housed in a lower part of a rear side of second housing  128 . Idler gear  500  is arranged so as to be meshed with an output gear fixed to a secondary pulley  30  and differential gear  600 .  
         [0033]     [Structure Surrounding the Oil Cooler] 
         [0034]      FIG. 5  is an expanded view of oil cooler installation portion  122  viewed from first housing  110  and  FIG. 6  shows a partial cross sectional view of oil cooler installation portion  122  shown in  FIG. 4  and an expanded view of oil cooler  730 .  
         [0035]     As shown in  FIG. 5 , oil cooler installation portion  122  is formed with a flat oil cooler installation surface  122   a  to attach oil cooler  730 . In addition, a supply oil passage open portion  123   a  opened to a surface of oil cooler installation portion  122   a  and communicated with oil supply passage  123  and opened to the surface of oil cooler installation portion  124   a  communicated with exhaust oil passage  124 . Furthermore, a filter inserting portion  124   b  having a larger diameter than exhaust oil passage opening portion  124   a  is formed on exhaust oil passage opening portion  124   a.    
         [0036]     Filter  750  is not integrally formed within oil cooler  730  as shown in  FIG. 6  but extended externally from oil cooler  730 . Filter  750  is removably inserted into a filter inserting portion  124   b  formed in the internal of oil cooler installation portion  122 . A lubricating oil chamber of oil cooler  730  is attached on supply oil opening portion  123   a  and supply oil passage opening portion  124   a  so as to enable supply and receipt (delivery) of the lubricating oil.  
         [0037]     Next, an action will be described below.  
         [0038]     [Action of Hydraulic Circuit] 
         [0039]     When the engine is driven, a driving force is transmitted to driven sprocket  701  via drive sprocket  50  and chain  51  installed on transmission input axle  20  so that vane pump  700  is driven. When vane pump  700  is driven, the oil stored in oil pan  740  is supplied to vane pump  700  after its foreign matter is removed from oil strainer  720 . Vane pump  700  develops a hydraulic pressure from the oil supplied thereto and supplies the hydraulic pressure to control valve unit  720 . Control valve unit  720  adjusts the hydraulic pressure of the oil and supplies the working oil to each device. Oil cooler  730  sucks the oil which is not supplied to each device and the oil stored in oil pan  740 . The sucked oil is supplied to the lubricating oil chamber, the oil in the lubricating oil chamber is cooled by means of the coolant in the coolant chamber adjoined to the lubricating oil chamber via a partitioning wall, and, thereafter, the foreign matter in the lubricating oil filter  750  installed on filter inserting portion  124   b  of oil cooler  730  is removed and supplied to each device.  
         [0040]     [Action of Drive System] 
         [0041]     Torque converter  200  augments the torque transmitted from the engine during a low vehicle speed and engages the lock-up clutch during the high vehicle speed during a high vehicle speed to transmit the driving force from the engine to forward-and-backward switching mechanism  300 . In forward-and-backward switching mechanism  300 , the inputted revolution is directly outputted with the sun gear and ring gear integrally engaged by means of the forward clutch during the forward travel. On the other hand, during the backward run of the vehicle, the backward brake fixes the carrier of forward-and-backward switching mechanism  300  to second housing  120  so as to reduce and output the inputted revolution in the reverse revolution.  
         [0042]     In belt type continuously variable transmission mechanism  400 , a cylinder chamber to modify a groove width by means of the magnitude of the hydraulic pressure is disposed on a back surface of each movable pulley of primary pulley  410  and secondary pulley  420 . By controlling a propelling force in a direction of a rotary axle pressing belt  430 , an effective winding radius of belt  430  is modified and a gear shift in an unlimited stage can be achieved.  
         [0043]     The driving force shifted by belt type continuously variable transmission  400  is transmitted to drive wheels via output gear  40 , idler gear  500 , and differential gear  600 .  
         [0044]     Next, advantages of the oil cooler installation structure of the transmission in the preferred embodiment will be described below.  
         [0045]     (1) In transmission casing  100 , supply oil passage  123  and supply oil passage opening portion  123   a  to supply the oil to oil cooler  730  and exhaust oil passage  124  and exhaust oil passage opening portion  124   a  to exhaust the oil from oil cooler  730  are formed. In addition, oil cooler  730  is attached onto oil cooler installation portion  122  so as to enable the supply and receipt of the oil via supply oil passage opening portion  123   a  and supply oil passage opening portion  124   a . Thus, it is not necessary to connect transmission housing  100  with supply oil passage  123  and exhaust oil passage  124 . Hence, a workability during the assembly of oil cooler  730  can be improved, a reduction in the working labor hour, and a reduction in the piping space can be achieved. In addition, a reduction in the piping portion can achieve a light weight of the whole transmission.  
         [0046]     (2) Filter  750  is not integrally formed within oil cooler  730  but is extended externally and is inserted into filter inserting portion  124   b  which is communicated with exhaust oil passage  124 . Hence, it is not necessary to provide a filter space within oil chamber  730  and a small sizing of oil cooler  730  can be achieved.  
         [0047]     (3) since filter  750  is removably inserted into filter inserting portion  124   a , the workability during the exchange in filter  750  can be improved. It is noted that the term of removably represents that enabled to be taken out of.  
         [0048]     (4) Since oil cooler installation portion  122  is disposed on the upper portion of third housing chamber  129  projected within second housing  120 , a large sizing of transmission housing  100  due to the installation of oil cooler installation portion  122  can be suppressed to minimum.  
         [0049]     (5) Third housing  129  and oil cooler installation portion  122  are formed at the vehicular front portion when transmission housing  100  is mounted on the vehicle, namely, toward the radiator side. Hence, both of water feed passage  731  and supply water passage  732  to feed the coolant between the radiator and oil cooler  730  can be shortened and a loss of a cooling efficiency can be reduced.  
         [0050]     (6) Since supply oil passage  123 , exhaust oil passage  124 , and check oil passage  127  are mutually adjacently arranged, opening portions of respective oil passages located at control valve unit  720  can once be worked. Thus, the workability can be improved.  
         [0051]     (7). Since a plurality of check oil passages  127  are adjacently arranged, a tester  60  can be inserted into check oil passages  127  through a single direction, the workability during the checking can be improved.  
         [0052]     (8) Since transmission housing  100  and oil cooler installation portion  122  are integrally formed, the rigidity of transmission housing  100  can be increased.  
         [0053]     (9) Since control valve unit  720  and check oil passage  127  are concentrated and arranged on the lower portion, check oil passages  127  can be shortened. The loss in the hydraulic pressure when the hydraulic pressure of the control valve is checked can be reduced so that a more accurate check can be made.  
         [0054]     This application is based on a prior Japanese Patent Application No. 2004-289629 filed in Japan on Oct. 1, 2004, the disclosure of which is hereby incorporated by reference.  
         [0055]     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. For example, although, in the preferred embodiment, the three members of first housing  110 , second housing  120 , and third housing  130  constitute transmission housing  100 , transmission housing may be constituted by a multiple number of members. In the preferred embodiment, the oil cooler is installed on the oil cooler installation portion formed on the transmission housing of the belt type continuously variable transmission. The present invention is applicable to a multiple geared automatic transmission, a toroidal continuously variable transmission, or any other type of the transmission in which the shift mechanism within transmission housing is lubricated with oil. The scope of the invention is defined with reference to the following claims.