Control apparatus of automatic transmission for vehicle and control method of automatic transmission for vehicle

In a vehicle having a continuously variable transmission, a road surface gradient estimation block for calculating a road surface gradient and a target vehicle speed value decision block for deciding a vehicle speed according to the road surface gradient are provided. During a vehicle running, when the road surface gradient becomes larger than a stored judgment value, a target vehicle speed is prepared in accordance with a vehicle speed at a time a road gradient value exceeds over an establishment value, a transmission ratio is controlled to have the target speed. Accordingly, a drive force in response to the road surface gradient can be carried out without a change-over of a transmission mode by a driver himself.

BACKGROUND OF THE INVENTION 
 The present invention relates to a control apparatus in which in particular
 a continuously variable transmission among automatic transmission for a 
 vehicle s becomes to be as a control subject and a control method thereof,
 and in particular relates to a control apparatus of an automatic 
 transmission for a vehicle where even a road gradient of a road surface in
 which a vehicle runs varies, a necessary driving force or an engine brake 
 can be obtained automatically and thereby the vehicle can be run safely 
 and a control method of an automatic transmission for a vehicle. 
 Up to now, as to a control method of an automatic transmission for a 
 vehicle, for example, as described in Japanese application patent 
 laid-open publication No. Sho 63-57953, one method has been known in which
 a present transmission ratio (a present pulley ratio) is requested by a 
 pulley ratio between an input side pulley (a primary pulley) and an output
 side pulley (a secondary pulley) of a continuously variable transmission 
 (CVT) and a rotation number of the pulley and a control of a transmission 
 ratio (a pulley ratio) is controlled to coincide this present transmission
 ratio (the present pulley ratio) with a target transmission ratio (a 
 target pulley ratio) which is requested according to a state amount of a 
 vehicle which has memorized in advance in a control apparatus, or another 
 method has known in which an input side pulley rotation number is varied 
 to coincide to a target input side pulley rotation number. 
 Further, it will be explained in concretely, from the target input side 
 pulley rotation number which is requested by a running condition of the 
 vehicle the target transmission ratio (the target pulley ratio) is 
 calculated and a command value for operating a transmission use actuator 
 of an automatic transmission is calculated from the target transmission 
 ratio (the target pulley ratio) and this command value is outputted. 
 Further, as a control method, a total value of a feed forward loop and a 
 feed back loop is made as a command value of a transmission use actuator, 
 such a feed back loop is calculated a command value according to a 
 proportional and integral execution in which a difference between the 
 target input pulley rotation number and an actual input pulley rotation 
 number is formed as a deviation. 
 In the above stated prior arts, during a flat road surface running there is
 no transmission chock different from a vehicle having a stepped stages 
 transmission and the performances such as an acceleration feeing are good,
 however when there is a road surface gradient, following problems occur. 
 For example, when the vehicle is on a down hill, a driver returns an 
 acceleration pedal by hoping an engine brake with an aim for lowering a 
 vehicle speed, however in a case of the conventional automatic 
 transmissions a shift-up causes by returning the acceleration pedal and 
 the vehicle speed is increased and the driver is caused to have a 
 consideration which differs from his intention and according to the 
 circumstances the driver may be given an afraid about a fear feeling. 
 Accordingly, during the down hill the driver carries out frequently a foot 
 brake, however following conditions cause in which by stepping 
 continuously the foot brake the brake oil is boiled and then the brake 
 becomes ineffective or a brake pad is worn early and then the brake 
 becomes ineffective. 
 As the countermeasures against the above facts, to making effectively the 
 effect of the engine brake during the down hill in the automatic 
 transmission the driver can carries out positively the change-over of a 
 range (a range selection) by the shift-down, as described in a vehicle use
 explanation. However, there is a report in which the driver who carries 
 out positively the range change-over (the range selection) is few, 
 accordingly it is necessary to carry out a countermeasure using a control 
 method. 
 Further, when an up hill (a hill climb) continues, when a trample down of 
 the acceleration pedal is not carried out, the vehicle speed lowers 
 naturally. In a case of abrupt climb road gradient, it is necessary to 
 carry out the trample down largely and by this trample down, the 
 shift-down is carried out, accordingly a drive torque is increased. 
 In the case of the vehicle having the continuously variable transmission 
 (CVT), together with the trample down of the acceleration pedal, the 
 transmission ratio (the pulley ratio) is changed gradually to a low side. 
 However, in the case of the abrupt climb road gradient, it is necessary to
 carry out the range change-over (the range selection) by the driver and 
 then the driver may be given to feel a nuisance. 
 On the other hand, in a microprocessor installed in an interior portion of 
 the control apparatus of the automatic transmission, the drive torque and 
 the road surface gradient are estimated and executed from an engine 
 condition amount such as an engine rotation number and a throttle valve 
 opening degree etc. and the transmission ratio is controlled suitably. 
 As a recently technical tread, in a case of a lean air fuel ratio control 
 engine and a fuel direct injection system engine, due to an increase of 
 the parameters for requesting an output torque and a change in time lapse,
 the estimation and execution of the drive torque and the road surface 
 gradient becomes complicatedly. 
 SUMMARY OF THE INVENTION 
 An object of the present invention is to provide a control apparatus of an 
 automatic transmission for a vehicle wherein a driving force in response 
 to a road surface gradient can be obtained by a driver himself without a 
 change-over of a transmission mode and a control method of an automatic 
 transmission for a vehicle. 
 Further, in a non-conventional system such as a lean air fuel ratio control
 engine and a fuel direct injection system engine, a transmission ratio (a 
 pulley ratio) is controlled automatically in response to a road surface 
 gradient, and the transmission ratio can be controlled automatically, in a
 case of a down hill road gradient a moderate engine brake suited to the 
 road gradient can be obtained and further in case of an up hill (a hill 
 climb) road gradient a moderate drive force suited to the road gradient 
 can be obtained. 
 According to the present invention, in a control apparatus of an automatic 
 transmission for a vehicle, a command value is calculated in response to 
 an engine rotation number, an input side pulley rotation number of a 
 continuously variable transmission (CVT), and an information indicating a 
 condition of a vehicle such as a vehicle speed of the vehicle and a 
 throttle valve opening degree. 
 According to the above stated command value a command is inputted, by 
 varying an interval of a V shape groove of an input side pulley (a primary
 pulley) and an output side pulley (a secondary pulley) and by varying a 
 pulley winding valid radius of a belt which is hung between said both 
 pulleys (the primary pulley and the secondary pulley), a transmission 
 ratio (a pulley ratio) is changed continuously variable and then a 
 transmission control is carried out, the control apparatus has a road 
 gradient estimation block for calculating a road gradient of a running 
 road surface and a target vehicle speed value decision block for deciding 
 a speed of the vehicle in accordance with the road gradient of the road 
 surface, and the transmission ratio (the pulley ratio) is controlled to 
 have the vehicle speed having a constant value under a basis of the 
 vehicle speed when the vehicle is on at the road gradient. 
 Further, the road gradient estimation block receives the information for 
 indicating the engine condition from a control apparatus of the engine and
 this road gradient estimation block comprises a torque calculation block 
 for estimating the drive torque of the vehicle, a running load resistance 
 calculation block for calculating the running load resistance under a 
 basis of the vehicle speed, and an acceleration torque calculation block 
 for calculating the acceleration torque of the vehicle according to the 
 vehicle. 
 With the above stated means, a target value of the vehicle speed is 
 requested in accordance with the stimulation torque taking into in 
 addition to the executed torque, the running resistance, and the 
 acceleration torque and the vehicle is controlled by requesting the most 
 suitable transmission ratio (pulley ratio) to follow an actual vehicle 
 speed. As a result, in the case of the down hill road gradient the 
 suitable engine torque can be obtained and further in the case of the up 
 hill road gradient the suitable driving force against the road gradient 
 can be obtained.

DESCRIPTION OF THE INVENTION 
 Hereinafter, a control apparatus of an automatic transmission for a vehicle
 and a control method of an automatic transmission for a vehicle of various
 embodiments according to the present invention will be explained referring
 to drawings. 
 FIG. 1 is a system construction view showing a portion of a power train 
 which comprises an internal combustion engine of a vehicle and a 
 continuously variable transmission (hereinafter, it is called as CVT). 
 In FIG. 1, the vehicle comprises an internal combustion engine 1, an air 
 cleaner 10 for cleaning and unifying the air which is inhaled by the 
 engine 1, an air intake conduit 11 for leading the cleaned and purified 
 air by the air cleaner 10 to the engine 1, a throttle valve 12 for 
 adjusting an air mount which passed through the air intake conduit 11, an 
 acceleration pedal 16 for operating a valve opening degree of the throttle
 valve 12, an exhaust air pipe 14 for leading an exhaust air from the 
 engine 1 to an outside portion. 
 The vehicle comprises further an oxygen sensor 24 for detecting an oxygen 
 concentration in the exhaust gas, a fuel injector 15 for injecting the 
 fuel in a respective cylinder of the engine 1, a continuously variable 
 transmission CVT 2 coupled to an output shaft of the engine 1, driving 
 wheels 8 to which a driving force from the engine 1 is transmitted, a 
 drive shaft 7 for driving the driving wheel 8, a differential gear 6 for 
 connecting a propel shaft 5 and a drive shaft 7, an engine control unit 30
 for controlling the engine 1, and a continuously variable transmission CVT
 control unit 40 for controlling the continuously variable transmission CVT
 2, and a respective control unit 30 and a respective continuously variable
 transmission CVT control unit 40 are connected mutually to a local area 
 network LAN 77. 
 The continuously variable transmission CVT 2 has a torque converter 3 which
 is connected directly to the output shaft of the engine 1 and a 
 continuously variable transmission mechanism 4 which is connected directly
 to an output shaft of the torque converter 3. The torque converter 3 has a
 pump 3a which is connected directly to the output shaft of the engine 1 
 and a stator 3c which is provided between the pump 3a and a turbine 3b 
 through an oil material. 
 The continuously variable transmission CVT mechanism 4 comprises a primary 
 pulley 19 which is an input side pulley and receives the driving force 
 from the torque converter 3, a secondary pulley 20 which is an output side
 pulley and is positioned oppositely to the primary pulley 19, and a metal 
 belt 9 for transmitting the driving force to the secondary pulley 20 from 
 the primary pulley 19. 
 The transmission control (the shift control) is carried out by varying the 
 transmission ratio (the pulley ratio) to make continuously variable, 
 namely a V shape groove interval between the primary pulley 19 and the 
 secondary pulley 20 is varied and a pulley winding effective radius of the
 belt 9 which is hang between the primary pulley 19 and the secondary 
 pulley 20 is varied. 
 The move of the primary pulley 19 and the secondary pulley 20 is carried 
 out by operating a hydraulic cylinder (not shown in figure) by the oil 
 pressure which is supplied by a hydraulic pressure circuit 17. Further, 
 since the oil pressure is changed by the temperature, in the hydraulic 
 pressure circuit 17 an automatic transmission fluid ATF sensor 28 for 
 detecting the oil pressure temperature is provided. 
 The rotation number of the primary pulley 19 is detected according to a 
 primary rotation sensor 25 for detecting a primary rotation number Np 
 which is the rotation number of the primary pulley 19 and further the 
 rotation number of the secondary pulley 29 is detected according to a 
 secondary rotation sensor 26 for detecting a secondary rotation number Ns 
 which is the rotation number of the secondary pulley 20. Since the 
 rotation of the secondary pulley 20 is transferred to the driving wheel 8 
 through the differential gear 6, the secondary rotation number Ns is 
 proportional to the vehicle speed. 
 To the air intake conduit 11, an air flow sensor 21 is provided and detects
 an air flow amount (an air flow value) Qa of the air which passes through 
 the air intake conduit 11. To the throttle valve 12, a throttle valve 
 opening degree sensor 22 is provided and detects a throttle valve opening 
 degree Tvo which expresses the opening degree of the throttle valve 12. 
 The acceleration pedal 16 and the throttle valve 12 are mechanically linked
 with in this embodiment according to the present invention, when an 
 operation amount of the acceleration pedal 16 is zero (0), the throttle 
 valve opening degree Tvo becomes zero (0). Accordingly, the detection of 
 the throttle valve opening degree Tvo corresponds to the indirect 
 detection of the operation amount of the acceleration pedal 16. 
 Even when the throttle valve opening degree Tvo is zero (0), to maintain an
 idling condition, a bypass conduit (not shown in figure) is provided to 
 the air intake conduit 11 and through this bypass conduit the rare air is 
 supplied to the engine 1. An idle speed valve 13 adjusts the above stated 
 air flow amount Qa. To a crank shaft (not shown in figure) which is an 
 output shaft of the engine 1, a crank angle sensor 23 is provided and 
 detects an engine rotation number Ne which is the rotation number of the 
 engine 1. To a suspension not shown in figure, a vehicle weight sensor 27 
 is provided and detects an actual vehicle weight. 
 The engine control unit 30 carries out controls the fuel injector 15, the 
 idle speed valve 13 and an ignition circuit not shown in figure in 
 response to the information from the air flow sensor 21, the throttle 
 valve opening degree sensor 22, an oxygen sensor 24, and a continuously 
 variable transmission CVT control unit 40. Further, the continuously 
 variable transmission CVT control unit 40 carries out a control of a 
 transmission operation valve (a shift valve) 18 in response to the 
 information from the primary rotation sensor 25, the secondary rotation 
 sensor 26, the vehicle weight sensor 27, the ATF sensor 28 and the engine 
 control unit 30. 
 FIG. 5 is a construction view of the engine control unit 30 or the 
 continuously variable transmission CVT control unit 40. The above stated 
 the engine control unit 30 or the continuously variable transmission CVT 
 unit 40 has a central processing unit 71 (hereinafter, it is called as 
 CPU) for carrying out various kinds executions, a read-only memory 72 
 (hereinafter, it is called as ROM) for carrying out the execution by CPU 
 71, a random access memory 73 (hereinafter, it is called as RAM) in which 
 the data is stored temporarily. 
 The above stated the engine control unit 30 or the continuously variable 
 transmission CVT unit 40 further has an input and output interference 
 circuit 75 for receiving the signals from the various kinds sensors and 
 for outputting the signals to the various valves of the transmission 
 operation valve (the shift valve) 18 etc. and the actuators, a local area 
 network control circuit 76 (hereinafter, it is called as LAN control 
 circuit) for carrying out the transfer of the data between the engine 
 control unit 30 and the continuously variable transmission CVT control 
 unit 40, and a bus 74 for connecting to carry out enable mutually for the 
 transfer of the data between these above stated various elements. 
 With the hardware construction of the above stated engine control unit 30 
 and the continuously variable transmission CVT control unit 40, the 
 software construction shown in FIG. 2 is practiced. FIG. 2 shows a control
 apparatus of an automatic transmission for a vehicle and a control method 
 of an automatic transmission for a vehicle of a first embodiment according
 to the present invention and FIG. 2 shows a control block diagram of the 
 control software which is carried out in the continuously variable 
 transmission CVT control unit 40. 
 The input variables are the engine rotation number Ne 32, the primary 
 pulley rotation number Np 33, the secondary pulley rotation number NS 34, 
 a pulley ratio ip 31 which is a rate of the primary pulley rotation number
 Np 33 and the secondary pulley rotation number Ns 34, the throttle valve 
 opening degree Tvo 36, and a fuel basic injection pulse width data Tp 39 
 which receives from the engine control unit 30 according to a LAN 
 communication line. 
 As shown in FIG. 2, a block 4 includes a torque calculation block 42 for 
 requesting a drive shaft torque To of the continuously variable 
 transmission CVT 2 shown in FIG. 1, a running resistance calculation unit 
 43, a vehicle speed differentiation execution block 44, an acceleration 
 torque calculation block 45 and then a road surface gradient .theta. is 
 requested. 
 Next, as shown in FIG. 2, in a target vehicle speed value decision block 
 47, the vehicle speed when the road surface gradient .theta. becomes 
 larger than a value of an advanced establishment road surface gradient has
 stored, and in accordance with the above stated vehicle speed the target 
 vehicle speed is decided. 
 In the target transmission ratio calculation block 48 in a block 50, the 
 target transmission ratio is calculated in accordance with the target 
 vehicle speed which is decided in the target vehicle speed value decision 
 block 47, the secondary pulley rotation number Ns 34 which indicates a 
 present vehicle speed, the primary pulley rotation number Np 33, and the 
 throttle valve opening degree Tvo 36, and the calculated target 
 transmission ratio is compared with the pulley rotation ratio ip 31 which 
 indicates a present actual transmission ratio. 
 In a transmission ratio operation command output block 49 an operation 
 amount of the transmission operation valve (the shift valve) 18 is 
 outputted. In this block 50 is a common continuously variable transmission
 CVT transmission ratio proportion unit of the conventional continuously 
 variable transmission CVT. 
 Next, FIG. 3 is a detailed control block diagram of the torque calculation 
 block 42 shown in FIG. 2. 
 The input signals are the engine rotation number Ne 32, the primary pulley 
 rotation number Np 33, the secondary pulley rotation number Ns 34, and the
 fuel basic injection pulse width data Tp 39. In FIG. 2, the pulley 
 rotation ratio ip 31 is indicated as the input signal, since the pulley 
 rotation ratio ip 31 is requested in accordance with the primary pulley 
 rotation number Np 33 and the secondary pulley rotation number Ns 34, in 
 FIG. 3, the pulley rotation ratio ip 31 is requested in the torque 
 calculation block 42. 
 An essential portion of the torque calculation block 42 is comprised of a 
 torque converter characteristic block 80 and the fuel basic injection 
 pulse width data Tp--an engine torque characteristic block 81. 
 In a block 57 of the torque converter characteristic block 80, a ratio 
 Np/Ne between the primary pulley rotation number Np 33 and the engine 
 rotation number Ne 32 is requested. This obtained ratio forms a pulley 
 ratio (a speed ratio) e of the torque converter. 
 In a torque converter ratio characteristic block 52, using a stored pulley 
 ratio e of the torque converter--a torque ratio curve line, a torque ratio
 t of the torque converter is requested by the pulley ratio e. Further, in 
 a torque converter pump capacity characteristic block or an input capacity
 characteristic block 53, using a stored pump capacity coefficient curve 
 line or a stored input capacity coefficient curve line of the torque 
 converter, a pump capacity coefficient Cp of the torque converter is 
 requested by the pulley ratio e. 
 In a block 54, the engine rotation number Ne 32 is multiplied, and in a 
 block 55 a pump torque Tpo of the torque converter is requested by 
 multiplying the squared engine rotation number Ne.sup.2 to the pump 
 capacity coefficient Cp which is calculated in the torque converter pump 
 capacity characteristic block 53. 
 In a block 84 in the fuel basic injection pulse width data Tp--the engine 
 torque characteristic block 81, using the stored fuel basic injection 
 pulse width data Tp 39 and a torque characteristic of the engine torque 
 Te, the engine torque Te is requested. 
 Next, in a block 57, the pump torque Tpo or the engine torque Te is 
 selected. As to this selection condition, for example, a standard value 
 against the pulley ratio e is provided, and when the pulley ratio e is 
 smaller than the standard value the pump torque Tpo is selected, on the 
 other hand when the pulley ratio e is larger than the standard value the 
 engine torque Te is selected. 
 In a case of the combination in which the pump torque Tpo which is 
 requested by the pump capacity coefficient Cp of the torque converter and 
 the pulley ratio e are large, and when the pulley ratio e is large on the 
 pump capacity coefficient curve line of the torque converter which is 
 stored in the torque converter pump capacity characteristic block 53, the 
 pump capacity coefficient Cp becomes small and accordingly an affect of 
 the execution error becomes large. 
 In particular, in a condition where the torque converter presents to a be a
 lockup, the error becomes large, as a result an acute pump torque Tpo can 
 not be requested. Therefore, in a case where the pulley ratio e is large, 
 the engine torque Te is selected. 
 In a block 58, a turbine torque Tt which is a torque of the output shaft 
 side of the torque converter is calculated by multiplying the selected 
 pump toque Tpo or the selected engine torque Te to the torque ratio t. 
 This turbine torque Tt is the torque which corresponds to the input torque
 of the continuously variable transmission CVT 2 shown in FIG. 1. 
 In a block 59, the drive shaft torque To 37 of the continuously variable 
 transmission CVT 2 is calculated by multiplying the turbine torque Tt to 
 the pulley rotation ratio ip and further multiplying a final gear ratio or
 a final reduction ratio in a block 83. 
 Next, a method for requesting the road surface gradient .theta. will be 
 explained referring to the block 41 shown in FIG. 2. 
 The drive shaft torque To is indicated by an addition value of a flat 
 ground running load resistance torque Tr, an acceleration resistance 
 torque T.sub..alpha., and a road gradient torque T.sub..theta.. 
 Accordingly, the road gradient torque T.sub..theta. is expressed by a 
 following formula (1). 
EQU T.sub..theta. =To-Tr-T.sub..alpha. (1) 
 In the block 41 shown in FIG. 2, the road gradient torque T.sub..theta. is 
 requested from the drive shaft torque To which is calculated by the torque
 calculation block 42, and from the flat road load resistance torque Tr 
 which is calculated by the running load resistance calculation block 43, 
 the acceleration resistance T.sub..alpha. which is requested by the 
 vehicle speed differentiation execution block 44 and the acceleration 
 torque calculation block 45. In the block 46, the road surface gradient 
 .theta. is requested in accordance with the following executions. 
 The flat road running load resistance torque Tr, the acceleration 
 resistance torque T.sub..alpha., and the road gradient torque 
 T.sub..theta. are expressed according to following formulas (2), (3) and 
 (4), respectively. 
EQU Tr=(.mu.r.times.W+ka.times.V.sup.2).times.Pt (2) 
EQU T.sub..alpha. =(W.times.Wr).times..alpha..times.Rt/g (3) 
EQU T.sub..theta. =W.times.sin .theta..times.Rt (4) 
 Herein, .mu.r is a rolling friction resistance coefficient, W an actual 
 vehicle weight, ka air resistance coefficient, V vehicle speed, Rt a 
 radius of tire, Wr rotation inertia weight, .alpha. acceleration velocity,
 and g gravity acceleration velocity. 
 Firstly, from the formula 2 and the formula 3, the flat road running load 
 resistance torque Tr and the acceleration resistance torque T.sub..alpha. 
 are requested, from the drive shaft torque To which is requested by the 
 torque calculation block 42, the flat road running load resistance torque 
 Tr and the acceleration resistance torque T.sub..alpha. are subtracted and
 then the road gradient torque T.sub..theta. is requested. And substituting
 this requested road gradient torque T.sub..theta. for the formula 4, the 
 value sin .theta. of the road gradient is requested, and then the road 
 surface gradient .theta. can be requested. 
 FIG. 4 is a control block diagram showing a detailed construction of the 
 block 41 shown in FIG. 2. The input signals are the same shown in FIG. 1 
 and are omitted in FIG. 4. Further, in the actual vehicle weight W 28, the
 signal which is detected by the vehicle weight sensor 27 shown in FIG. 1 
 can be made as the input signal or the input signal can be stored in 
 advance in the acceleration torque calculation block 45 etc. shown in FIG.
 2. 
 In FIG. 4, in the running load resistance calculation block 43, from the 
 vehicle speed V which is requested by the actual vehicle weight W 38 which
 is detected by the vehicle weight sensor 27 shown in FIG. 1 and the 
 secondary pulley rotation number Ns 34 which is detected in the secondary 
 rotation sensor 26, in accordance with the above stated formula 2, the 
 flat road running torque Tr is requested. 
 Next, in the acceleration torque calculation block 45, the acceleration 
 velocity .alpha. which is requested in the vehicle speed differentation 
 execution block 44 is squared to a value which is requested in the block 
 84, in accordance with the above stated formula 3, the acceleration torque
 T.sub..alpha. is requested. 
 Further, from the drive shaft torque To which is requested in the torque 
 calculation unit 42, in a block 46a the flat road running load resistance 
 Tr is subtracted, in a block 46b the acceleration resistance torque 
 T.sub..alpha. is subtracted, accordingly then the road gradient torque 
 T.sub..theta. is requested. Further, in the block 85 and in the block 86, 
 in accordance with the formula 4, the road gradient sin .theta. is 
 requested. The road gradient sine or the converted road surface gradient 
 .theta. is sent to the target vehicle speed value decision block 47. 
 Further, as stated in the above, herein against the vehicle weight sensor 
 27 is provided to obtain the vehicle weight W, in a motor car (an 
 automobile) in which the change in the vehicle weight W is not large 
 compared with the truck, the standard vehicle weight W may be stored in 
 advance, for example, such a vehicle weight W in which two persons ride 
 on. 
 Further, in place of the detection of the vehicle weight w by means of the 
 vehicle weight sensor 27, under the condition in which the road surface 
 gradient .theta. and the drive shaft torque To are not varied, the vehicle
 weight W can be estimated according to the vehicle speed V at some time 
 and the change of the vehicle speed V at a time after the some time 
 lapses. 
 Further, as to the acceleration velocity .alpha., the secondary pulley 
 rotation number Ns which is detected by the secondary rotation sensor 26 
 is performed with the differential execution by the time, and the 
 acceleration velocity a can be obtained, however by providing an 
 acceleration sensor to a vehicle body then the acceleration velocity 
 .alpha. may be obtained directly. 
 Next, the control of the automatic transmission for a vehicle of the above 
 stated embodiment according to the present invention will be explained 
 referring to FIG. 6B and FIG. 7. FIG. 6A is a control of the automatic 
 transmission for a vehicle according to the prior art. 
 FIG. 6B is a general transmission schedule characteristic line of the 
 continuously variable transmission CVT 2 shown in FIG. 1. As a horizontal 
 axis the vehicle speed V or the secondary pulley rotation number Ns is 
 indicated, and as a vertical axis the primary pulley rotation number Np or
 the engine rotation number Ne is indicated. 
 FIG. 6A is the transmission schedule characteristic line of the 
 continuously variable transmission CVT according to the prior art. As a 
 horizontal axis the vehicle speed V or the secondary pulley rotation 
 number Ns is indicated, and as a vertical axis the primary pulley rotation
 number Np or the engine rotation number Ne is indicated. 
 In the prior art technique shown in FIG. 6A, a target primary pulley 
 rotation number Npt which is a control target is requested in accordance 
 with the throttle valve opening degree Tvo (A-D) . . . , Tvo (B-C) and the
 vehicle speed V. 
 Herein, differing from the stepped stage transmission, however in the 
 continuously variable transmission CVT, the transmission ratio, namely the
 pulley rotation ratio ip in the prior art is expressed only few plural 
 linear lines, for example four lines, (0-a, 0-b, 0-c, 0-d, etc.) which 
 pass through an original point zero (0). 
 On the other hand in the present invention, in addition to the plural 
 linear lines which pass through an original point zero (0) but it has a 
 feature that it can obtain any place within a range A-B-C-D-A, namely it 
 can obtain a numberless linear line which passes through an original point
 zero (0). 
 Further, in the continuously variable transmission CVT 2 in the embodiment 
 according to the present invention and according to the prior art, a liner
 line 0-A-B indicates the most large portion of the transmission ratio and 
 it is impossible to take the transmission ratio (the pulley ratio) more 
 than the above stated transmission ratio. 
 FIG. 6B is the transmission schedule characteristic line in the case of 
 this embodiment according to the present invention. An area enclosed by a 
 line A-B-C-E-F-A is an area which in common is called a sport mode etc., 
 and this is set to has the high engine rotation number Ne against to some 
 vehicle speed V. In this sport mode, at an area enclosed by a line 
 C-E-F-D-C the vehicle is not operated. 
 Now, it is supposed a case where the vehicle is on the down hill having a 
 large road gradient. From a requirement for effecting the engine brake to 
 restrain an increase of the vehicle speed, the driver operates to return 
 the step-in of the acceleration pedal or separate completely his foot from
 the acceleration pedal and then the throttle valve opening degree Tvo is 
 directed to become a full-closing condition or a throttle valve shutting 
 condition. 
 In the transmission schedule characteristic line shown in FIG. 6A according
 to the prior art, when the normal running time is a point p1 and when the 
 throttle valve opening degree Tvo becomes the full-closing condition or 
 the throttle valve shutting condition and then the operation point 
 transfers to a point p2. The transmission ratio, provisionally, is shown 
 the transmission ratio in the stepped stage transmission, since it is made
 to become small in proportional to from the linear line 0-a to the linear 
 line 0-d, the transmission ratio is made to be an over-top, regardless the
 requirement of the engine brake the engine brake is not effected, then the
 vehicle speed is increased more and more directing for a direction of an 
 operation point p3. 
 On the other hand, according to the control method of the automatic 
 transmission for a vehicle of this embodiment according to the present 
 invention, since the driver can change over the modes shown in FIG. 6B, it
 is possible to obtain fully the engine brake. Namely, when the vehicle is 
 on the down hill, the driver can separate his foot from the acceleration 
 pedal then the throttle valve opening degree Tvo is made to present the 
 full-closing condition or the throttle valve shutting condition. The 
 operation point transfers from the point p1 to the point p2, and in 
 proportion to the increase in the vehicle speed the operation point move 
 to the point p3. 
 Herein, when the driver changes over the sport mode, the operation pint 
 transfers from the point p3 to a point p4 and the transmission ratio (the 
 pulley ratio) becomes large, accordingly the engine brake can be obtained 
 and the increase in the vehicle speed can be restrained. According to the 
 above embodiment according to the present invention, it is possible to 
 carry out automatically the change-over of the transmission schedule in 
 the down hill. 
 The driver who is not gotten skillful about the drive can not carry out 
 easily the above stated positive range change-over and since such a driver
 can not be obtained the necessary engine brake force, the driver carries 
 out frequently the foot brake and runs down the down hill. In a case of 
 the long length down hill, since the drive steps in continuously the foot 
 brake, a brake face is heated and a brake liquid is boiled and then the 
 foot brake can not be effect and there is a possibility to reach an 
 accident. 
 As a result, according to the control method and the control apparats of 
 the automatic transmission for a vehicle of this embodiment according to 
 the present invention, the vehicle speed V which is recognized as the down
 hill is memorized as the target vehicle speed Vt and the pulley rotation 
 ratio ip is controlled to become this target vehicle speed Vt as the 
 actual vehicle speed. In FIG. 6B, when the operation point transfers from 
 the point p1 to the point p2, the vehicle speed at the point p2 is made to
 have the target vehicle speed Vt. Next, to maintain the above stated 
 target vehicle speed Vt the primary pulley rotation number Np is varied, 
 and the pulley rotation ratio ip is control to be a point p5. 
 FIG. 7 shows a flow chart of the above stated control of the automatic 
 transmission for the vehicle of this embodiment according to the present 
 invention. For the simplification for the explanation, the flow chart is 
 shown after the condition of the road surface gradient .theta. is 
 requested. Further, each of the up hill road gradient and the down hill 
 road gradient is judged according to one constant as the judgment value. 
 In FIG. 7, in a block 101, the road surface gradient .theta. which is 
 obtained in the block 41 is compared with the judgment value of the road 
 surface gradient which is stored in advance in the memory etc. When the 
 road surface gradient .theta. is judged as larger than the judgment value,
 it proceeds to a block 102, however when the road surface gradient .theta.
 is judged as smaller than the judgment value, it proceeds to a block 106. 
 In the block 102, it judges whether a flag is zero (0) or not. When this 
 flag is zero (0), it means that the road surface gradient .theta. exceeds 
 at first the judgment value. When the flag is zero (0), it proceeds to a 
 block 103 and the present secondary pulley rotation number Ns is stored in
 the memory as a target secondary pulley rotation number Nst. And in a 
 block 104, a value of the flag is made to be one (1). 
 Next, from the present primary pulley rotation number Np and the target 
 secondary pulley rotation number Nst, in accordance with a following 
 formula 5, a target pulley rotation ratio ipt is requested. 
EQU ipt=Np/Nst (5) 
 In accordance with the target pulley rotation ratio (the target 
 transmission ratio) ipt, an operation amount to the transmission operation
 valve (the shift valve) 18 is decided in a transmission operation command 
 output unit 40 shown in FIG. 2 and as a result the transmission operation 
 (the shift operation) is carried out. 
 Next, in the block 102, when the flag is not zero (0), jumping over the 
 block 103 and the block 104, in a block 105 the target pulley rotation 
 ratio ipt is calculated. In the block 101, when the road surface gradient 
 .theta. is smaller than the judgement value, the flag is reset to be zero 
 (0), jumping over the block 103, the block 104, and the block 105, this 
 control is finished. The above stated control of the automatic 
 transmission for the vehicle of this embodiment according to the present 
 invention can be corresponded to any one of the up hill road gradient and 
 the down hill road gradient in accordance with the same principle. 
 A control apparatus of a vehicle use transmission and a method of a 
 automatic transmission for a vehicle of a second embodiment according to 
 the present invention will be explained referring to FIG. 8. Similar to 
 FIG. 2, FIG. 8 is a control block diagram of a control software which is 
 carried out in the continuously variable transmission CVT control unit 40.
 Compared with the control block diagram shown in FIG. 2, the control 
 diagram shown in FIG. 8 has a difference about only a signal which is 
 inputted to the torque calculation block 42. Namely, in place of the fuel 
 basic injection pulse width data Tp 39, in FIG. 8 an engine inhale air 
 amount Qa 90 is inputted. This signal is sent from the engine control unit
 31 through LAN 77 shown in FIG. 1. 
 In the torque calculation block 42 shown in FIG. 8, the fuel basic 
 injection pulse width data Tp--the engine torque characteristic stored in 
 the block 84 of FIG. 3 which is the detailed figure of the torque 
 calculation block 42 shown in FIG. 2 is placed to the engine inhale air 
 amount Qa--the engine torque characteristic shown in FIG. 10. Other 
 executions except for the above are similar to those of FIG. 2. In place 
 of the fuel basic injection pulse width data Tp 39, even using the engine 
 inhale air amount Qa 90 the road surface gradient can be estimated. 
 A control apparatus of a vehicle use transmission and a control method of 
 an automatic transmission for a vehicle of a third embodiment according to
 the present invention will be explained referring to FIG. 9. Similar to 
 FIG. 2, FIG. 9 is a control block diagram of a control software which is 
 carried out in the continuously variable transmission CVT control block 
 40. 
 Compared with the control block diagram shown in FIG. 2, the control 
 diagram shown in FIG. 9 has a difference about only a signal which is 
 inputted to the torque calculation block 42. Namely, the control diagram 
 shown in FIG. 9 has no fuel basic injection pulse width data Tp 39 shown 
 in FIG. 2. 
 In the torque calculation block 42 shown in FIG. 9, the fuel basic 
 injection pulse width data Tp--the engine torque characteristic stored in 
 the block 84 of FIG. 3 which is the detailed figure of the torque 
 calculation block 42 shown in FIG. 2 is placed to the throttle valve 
 opening degree Tvo--the engine torque characteristic shown in FIG. 11. 
 Other executions except for the above are similar to those of FIG. 2. In 
 place of the fuel basic injection pulse width data Tp 39, even using the 
 throttle valve opening degree Tvo the road surface face gradient can be 
 estimated. 
 According the above stated control apparatus of the automatic transmission 
 for the vehicle and the control method of the automatic transmission for 
 the vehicle of the various embodiments according to the present invention,
 in addition to the executed torque, from the estimation torque taking 
 under the consideration of the running resistance and the acceleration 
 torque, the target value of the vehicle speed is requested, then the 
 vehicle speed is controlled by requesting the optimum transmission ratio 
 to follow the actual vehicle speed. 
 As a result, without the driver himself carries out the change-over the 
 transmission range, in the case of the down hill road gradient the 
 suitable engine brake can be obtained and further in the case of the up 
 hill road gradient the suitable drive force against to the road gradient 
 can be obtained. 
 Further, even in the case of the engine which is not the conventional 
 system engine such as the lean burn air fuel ratio control engine and the 
 fuel direct injection system engine, the transmission ratio (the pulley 
 ratio) is controlled in accordance with the drive shaft torque, in 
 response to the road face condition, the transmission ratio can be 
 controlled automatically. 
 In the case of the down hill road gradient the suitable engine brake can be
 obtained and further in the case of the up hill road gradient the suitable
 drive force against to the road gradient can be obtained, accordingly the 
 transmission ratio can be controlled automatically. 
 As stated in the above, according to the control apparatus of the automatic
 transmission for the vehicle and the control method of the automatic 
 transmission for the vehicle according to the present invention, the drive
 force response to the road surface gradient can be obtained without the 
 change-over operation of the transmission mode by the driver himself.