JP2014149050A - Shift control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress rise of a primary pressure in accompany with gear change by suppressing gear change at an early timing in starting and accelerating, even when a continuously variable shift mode and a multistage shift mode are selectively switched.SOLUTION: A TCU (transmission control unit) 43 sets a shift mode to a multistage shift mode (S4) in detecting start of a vehicle or an accelerating operation after the start (S2, S3), and fixes a transmission ratio to one speed as a maximum transmission ratio of the multistage shift mode (S5). By fixing the shift ratio in starting and accelerating, to the maximum shift ratio, up-shifting at an early timing in start and accelerating, is suppressed.

Description

  The present invention has a continuously variable transmission mode and a multi-stage transmission mode as a transmission mode of a continuously variable transmission, and a vehicle in which the transmission gear ratio of the continuously variable transmission is fixed to a preset predetermined gear ratio during start acceleration. The present invention relates to a gear shift control device.

  Generally, since the torque converter at the time of starting acceleration is not engaged with a lock-up clutch, the engine torque is amplified and transmitted to the transmission.

  When the transmission is a continuously variable transmission (CVT), the torque from the torque converter is passed through a winding transmission element such as a drive chain or a drive belt that is passed between the primary pulley and the secondary pulley. Output to the drive wheel side. Each pulley has a transmission ratio at the time of start acceleration set to an optimum value by sandwiching the winding type transmission element by hydraulic pressure and changing the groove width.

  The clamp pressure (primary pressure, secondary pressure) for each pulley of the CVT is a torque (hereinafter referred to as “CVT input torque”) input from the torque converter to the primary of the CVT so as not to cause a slip between the pulley and the wound transmission element. And the target gear ratio, etc. As described above, the CVT input torque at the time of starting acceleration is abruptly increased while the torque from the engine is amplified by the torque converter, so that each clamp pressure must be increased accordingly.

  By the way, when the engine of the vehicle on which CVT is mounted is a diesel engine, the diesel engine can obtain the maximum torque at a low rotation (for example, about 1500 to 2000 [rpm]), and the maximum at about 3000 to 4000 [rpm]. Output is obtained. Therefore, for example, as described in FIG. 7A of Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-274756), in the fuel consumption priority shift control, the shift with the best fuel consumption rate is within the maximum output range. The transmission ratio of CVT is set so as to pass through the line.

  Even in CVT shift control, if you want to enjoy sporty running, make sure that there is a step in the gear ratio during upshifting or downshifting. As a multi-stage shift that is equivalent to an automatic transmission that can be shifted stepwise using a shift, a shift control that provides a sense of a step during acceleration is also known.

  For example, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-106615), a driver operates a select lever so that a CVT shift mode is set to a continuously variable transmission mode (hereinafter referred to as “CVT mode”) in which fuel consumption priority is set. Is referred to as a multi-speed mode suitable for sporty travel (hereinafter referred to as “A / T mode”).

  Also, recently, the shift control in the CVT mode is performed in the normal area, and when the driver depresses the accelerator pedal beyond the preset accelerator opening, the shift mode is automatically switched to the A / T mode. Such a shift control is also known.

  That is, as shown in FIG. 4, the shift control device has a CVT mode shift pattern shown in FIG. 4A and an A / T mode shift pattern shown in FIG. If the accelerator opening is within the threshold value (mode switching determination opening) indicated by a two-dot chain line in the figure when the accelerator pedal is depressed, the shift pattern for the CVT mode shown in FIG. Shift control is executed, and when the accelerator opening exceeds a threshold value (mode switching determination opening), the shift control is executed according to the A / T mode shift pattern shown in FIG.

JP 2010-274756 A JP 2011-106615 A

  In shift control in which the CVT mode and A / T mode are automatically switched according to the amount of depression of the accelerator pedal, when the driver depresses the accelerator pedal to accelerate the start, the accelerator pedal is gradually depressed from the released state. When starting, the CVT mode shift pattern shown in FIG. 4A is always selected, and the gear ratio is set according to this shift pattern. Further, the CVT mode and the A / T mode can be manually switched by a switch or the like, and when the CVT mode is selected at the time of starting, naturally, the shift control is performed according to the CVT mode shift pattern at the time of starting.

  The CVT adjusts the clamping pressure on the primary pulley to change the winding diameter of the winding type transmission element to perform shift control, and supplies a predetermined clamping pressure to the secondary pulley. Torque is transmitted to the drive wheel in a state where tension is applied to the hanging transmission element and slipping is prevented.

  By the way, the gear ratio of CVT at the start is set to the highest. In this case, since the winding diameter with respect to the primary pulley is minimum and the winding diameter of the secondary pulley is maximum, a large secondary pressure is required. On the other hand, since the primary pulley side transmits the driving force by pushing the winding type transmission element to the secondary pulley side, for example, in order to upshift in the low rotation high torque region, the primary pulley It is necessary to apply a high clamping pressure (primary pressure) to the winding drive force transmission element.

  Further, during start acceleration, the torque converter is not locked up, so the amplified torque is input to the primary pulley. Further, since the CVT mode shift pattern is generally set to a low-rotation high-torque shift characteristic that prioritizes fuel consumption, an upshift is started at a relatively early timing after starting. Thus, the CVT input torque is amplified by the torque converter, and the secondary pressure is set high. Therefore, when upshifting, the clamp pressure (primary pressure) supplied to the primary pulley is relatively low. It needs to be set high.

  As a result, in particular, the strength of the pressure chamber for supplying the primary pressure needs to be set higher by increasing the thickness of the case so as to withstand the primary pressure during acceleration. When the strength of the case is set high, there is a problem that the manufacturing cost is increased correspondingly, and not only the whole apparatus is increased in size, but also the fuel consumption is deteriorated due to an increase in weight.

  In view of the above circumstances, the present invention does not need to set the clamping pressure supplied to the pulley of the CVT at the time of starting acceleration higher than necessary, and it is possible to realize downsizing by simplifying the structure of the pressure chamber and reducing the weight. In addition, an object of the present invention is to provide a vehicle transmission control device that can improve fuel efficiency by reducing the weight.

  The present invention relates to a continuously variable transmission capable of continuously changing a transmission gear ratio, a continuously variable transmission mode capable of continuously setting a transmission gear ratio as a transmission mode of the continuously variable transmission, and the gear ratio set in stages. A vehicle having a multi-speed mode that can be switched, and a switching unit that selectively switches each of the shift modes; and a shift control unit that performs a shift control of the continuously variable transmission based on the shift mode selected by the switching unit. In the shift control device for a vehicle, the shift control means includes a start acceleration detecting means for detecting a start of the vehicle or an acceleration operation after the start, and an acceleration operation after the start or the start by the start acceleration detecting means. Start acceleration control means for fixing the gear ratio of the step transmission to a predetermined gear ratio set in advance.

  According to the present invention, even in the transmission control of the continuously variable transmission in which the continuously variable transmission mode and the multi-speed transmission mode are switched, the speed ratio at the time of start acceleration is fixed to a predetermined speed ratio set in advance. It is not necessary to set the clamping pressure applied to the pulley of the CVT at the time of start acceleration higher than necessary, and the size can be reduced by simplifying the structure of the pressure chamber and reducing the weight. Furthermore, fuel consumption can be improved by weight reduction.

Schematic configuration diagram of engine control system Schematic configuration diagram of continuously variable transmission Flow chart showing start acceleration control routine (A) is a conceptual diagram of a transmission map for continuously variable transmission mode, (b) is a conceptual diagram of a transmission map for multi-speed transmission mode. Characteristic chart showing the shift pattern during start acceleration (A) is a time chart showing changes in the turbine speed during start acceleration, and (b) is a time chart showing changes in primary pressure and secondary pressure during start acceleration.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 in FIG. 1 denotes a prime mover, and a diesel engine is illustrated in this embodiment. Accordingly, in the following description, the prime mover is replaced with a diesel engine.

  An intake passage 5 and an exhaust passage 6 are communicated with the combustion chamber 2 of the diesel engine 1 through an intake valve 3 and an exhaust valve 4. A throttle valve 10 is interposed on the upstream side of the intake passage 5.

  The throttle valve 10 is connected to a throttle actuator 11 driven by a control signal from an engine control unit (ECU) 41, and the throttle opening is set to a predetermined value by the operation of the throttle actuator 11. An intercooler 12 is interposed upstream of the throttle valve 10, and a compressor 13 a of the turbocharger 13 is interposed upstream of the intercooler 12. Further, an air cleaner 14 is interposed on the upstream side of the compressor 13 a of the turbocharger 13, and an intake air amount sensor 15 is interposed on the downstream side of the air cleaner 14. On the other hand, a turbine 13 b of the turbocharger 13 is interposed in the exhaust passage 6 of the diesel engine 1.

  Further, in the exhaust passage 6 on the downstream side of the turbine 13b, a diesel oxidation catalyst (DOC) 22 that mainly oxidizes hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas by catalytic reaction, and exhaust gas NOx storage / reduction catalyst (LNT) 23 that stores and reduces nitrogen oxide (NOx) in gas, soot, carbon soot, soluble organic components (Soluble Organic) in exhaust gas A diesel particulate filter (Diesel Particulate Filter; DPF) 24 that collects particulate matter (Particulate Matter; PM) such as Fraction (SOF) and sulfate (SO4) is inserted in order from the upstream side. .

  Next, the fuel injection system of the diesel engine 1 will be described. The diesel engine 1 employs a well-known common rail fuel injection system, and an injector 25 controlled by the ECU 41 is exposed to the combustion chamber 2. A glow plug 26 whose energization is controlled by a glow controller 27 is exposed in the vicinity of the injection nozzle of the injector 25 in the combustion chamber 2.

  The injector 25 is connected to a common rail 29 via a fuel pipe 28 branched to each cylinder, and a supply pump 30 that sucks and pressurizes fuel from a fuel tank (not shown) is connected to the common rail 29. The fuel boosted to a high pressure by the supply pump 30 is accumulated in the common rail 29, and the high pressure fuel is supplied to the injector 25 of each cylinder via the fuel pipe 28 to each cylinder.

  The supply pump 30 has an intake metering solenoid valve 31 that adjusts the intake amount, and the ECU 41 sets the discharge pressure of the supply pump 30, that is, the fuel pressure of the common rail 29, to an optimum value according to, for example, the engine speed and the load. Thus, the intake metering solenoid valve 31 is feedback-controlled.

  Next, an electronic control system centering on the ECU 41 will be described. The ECU 41 is configured around a known microcomputer including a CPU, a ROM, a RAM, an I / O interface, and the like.

  The ECU 41 includes an intake air amount sensor 15 for detecting the intake air amount, a crank angle sensor 32 for detecting the rotational position of the crankshaft 1a, and an accelerator opening detection means for detecting the accelerator opening AP [%] from the depression amount of the accelerator pedal. Various sensors and switches such as an accelerator opening sensor 33 and a vehicle speed sensor 34 as vehicle speed detecting means for detecting the vehicle speed V [Km / h] are connected.

  The CPU of the ECU 41 controls fuel pressure control, fuel based on signals from various sensors for detecting the diesel engine operating state and various control information input via the in-vehicle network 42 in accordance with a control program stored in the ROM. Various diesel engine controls such as injection control, intake air control, and supercharging pressure control are executed, and the operation state of the diesel engine 1 is maintained in an optimum state. For example, in fuel injection control, depending on the engine speed Ne [rpm] based on the signal from the crank angle sensor 32 and the accelerator opening AP detected by the accelerator opening sensor 33, the fuel injection amount or The injection timing is determined, and fuel is injected in a predetermined manner to the cylinder that has reached the injection timing. The diesel engine 1 shown in this embodiment can generate a high torque even when the engine speed is a low speed of 2000 [rpm] or less by combining with the turbocharger 13.

  Further, as shown in FIG. 2, the ECU 41 is a shift control unit (TCU) as a shift control means for controlling an automatic transmission 51 described later via an in-vehicle network 42 based on a communication protocol such as CAN (Controller Area Network). ) 43 and the like are connected to each control unit so as to be capable of bidirectional communication.

  Next, the configuration of the automatic transmission 51 will be described with reference to FIG. The automatic transmission 51 includes a torque converter 52 and a continuously variable transmission (CVT) 53.

  The torque converter 52 has a pump impeller 52a connected to the crankshaft 1a of the diesel engine 1, and a turbine shaft 52c connected to a turbine runner 52b facing the pump impeller 52a. Further, the turbine shaft 52c is connected to the pulley input shaft 53a of the CVT 53 via a forward / reverse switching device 53 constituted by a planetary gear mechanism or the like. A primary pulley 53b is pivotally supported on the pulley input shaft 53a. In addition, when the vehicle speed V at the time of starting acceleration reaches a preset lockup vehicle speed (about 15 to 20 [Km / h]), the torque converter 52 is engaged with a lockup clutch (not shown), and the crankshaft 1a. And the turbine shaft 52c are directly connected.

  The CVT 53 has a pulley output shaft 53c parallel to the pulley input shaft 53a, and a secondary pulley 53d is pivotally supported by the pulley output shaft 53c. Further, a winding transmission element 53e such as a drive belt or a drive chain is wound between the pulleys 53b and 53d. Further, a differential device 55b is connected to the pulley output shaft 53c through a reduction gear group 55a of the final reduction device 55. The differential device 55b has a drive shaft on which a front or rear drive wheel 56a is attached. 56 are continuously provided.

  The primary pulley 53b of the CVT 53 is provided with a primary pressure chamber 53f, and the primary pressure is supplied from the pressure control circuit 57 to the primary pressure chamber 53f. On the other hand, the secondary pulley 53d is provided with a secondary pressure chamber 53g, and the secondary pressure is supplied from the pressure control circuit 57 to the secondary pressure chamber 53g.

  The pulley width of the primary pulley 53b is adjusted by the primary pressure, and the secondary pulley 53d applies tension necessary for torque transmission to the winding transmission element 53e by the secondary pressure. The primary pressure and the secondary pressure are set by the TCU 43 based on the operating state of the diesel engine 1 and the like, and the desired gear ratio is obtained by controlling the groove widths of the pulleys 53b and 53d to be in an inversely proportional state through these pressures. Realized.

  Further, the TCU 20 detects a rotational speed (turbine rotational speed) Nt [rpm] of the turbine shaft 52c provided in the torque converter 52, and a rotational speed (secondary rotational speed) of the pulley output shaft 53c of the CVT 53. ) Sensors such as the secondary rotational speed sensor 62 for detecting Ns [rpm] are connected. Since the forward / reverse switching device 53 rotates integrally during forward travel, the turbine rotational speed Nt shows the same value as the rotational speed of the pulley output shaft 53c.

  Like the ECU 41 described above, the TCU 43 is configured around a known microcomputer including a CPU, ROM, RAM, I / O interface, and the like. The CPU controls the torque converter 52 according to a control program stored in the ROM. Lockup control for the provided lockup clutch, forward / reverse switching control of the forward / reverse switching device 53, and hydraulic pressure supplied to both pressure chambers 53f, 53g of the CVT 53 are controlled. In addition to the control program, the ROM stores fixed data such as a CVT mode shift map and an A / T mode shift map, which will be described later. A description of the lockup control for the lockup clutch and the forward / reverse switching control of the forward / reverse switching device 53 will be omitted.

  Further, the TCU 43 has a CVT mode and an A / T mode as shift modes. In the CVT mode, the gear ratio is continuously variably set with reference to the CVT mode shift map shown in FIG. 4A. The A / T mode is the A / T mode shown in FIG. With reference to the mode shift map, a preset fixed gear ratio is set stepwise. The shift map set for each shift mode is set so that an optimal gear ratio can be selected based on the vehicle speed V and the turbine speed Nt.

  The CVT mode and the A / T mode are switched based on the accelerator opening AP. That is, when the accelerator opening AP is equal to or less than a preset mode switching determination opening APo (for example, about APo = 50 to 70 {%]), the CVT mode is selected, and the CVT mode shown in FIG. The transmission ratio is set with reference to the transmission map. In addition, when the accelerator opening AP exceeds the mode switching determination opening APo, the A / T mode is selected, and the gear position is set with reference to the A / T mode shift map shown in FIG. 4B. The Note that the numbers in parentheses in FIG. 4 (b) indicate the shift speed. This A / T mode shift map is set to shift characteristics giving priority to output (horsepower) at which each shift stage can obtain the maximum output (horsepower). Therefore, sporty running performance can be obtained in the A / T mode. Thus, the TCU 43 has a function of selectively switching the shift mode based on the accelerator pedal opening AP, and this function corresponds to the switching means of the present invention.

  In the present embodiment, since the shift mode is automatically switched based on the accelerator pedal opening AP, the CVT mode is selected in the regular region where the accelerator pedal depression amount is small, and the shift control along the shift map for the CVT mode is executed. Is done. Also, A / T mode is selected for driving with the accelerator pedal depressed greatly, such as high-load driving on uphill roads, acceleration driving during high-speed driving, etc., and shifting along the A / T mode shift map Control is executed.

  As shown in FIG. 4, in this embodiment, the maximum transmission ratio of the CVT mode transmission map corresponds to the first speed of the A / T mode transmission map, and the minimum transmission ratio of the CVT mode transmission map is A / T. It corresponds to the 7th speed of the mode shift map, and the gear ratio is continuously set between the maximum speed ratio line corresponding to the 1st speed and the minimum speed line corresponding to the 7th speed in the CVT mode shift map. Has been.

  The shift map for CVT mode shown in FIG. 4A is set to a shift characteristic with priority on fuel consumption utilizing low rotational high torque with good combustion efficiency. Therefore, if the vehicle speed V increases in the travel after the start, the gear ratio is immediately upshifted accordingly. On the other hand, if the accelerator pedal opening AP exceeds the mode switching determination opening APo when the accelerator pedal is greatly depressed to accelerate, the shift mode is automatically switched to the A / T mode, and the shift characteristic of the multi-stage shift is achieved. It can be run.

  By the way, since the transmission ratio of the CVT 53 in a stopped state is set to the maximum (corresponding to the first speed in the A / T mode), the winding diameter of the winding transmission element 53e with respect to the secondary pulley 53d is large, and At that time, it is necessary to apply a large primary pressure to prevent slippage between the winding type transmission element 53e. Therefore, as shown in FIG. 4 (b), the secondary pressure Ps at the time of starting is temporarily increased to the maximum pressure, and after starting, the primary pressure is gradually changed over time and continuously decreased. Yes.

  On the other hand, at the time of starting acceleration, the lockup clutch of the torque converter 52 is in the unlocked state until the vehicle speed V reaches the lockup vehicle speed. Therefore, the output of the diesel engine 1 is torque amplified by the torque converter 52. It is transmitted to the pulley input shaft 53a (primary pulley 53b) of the CVT 53. The CVT input torque transmitted to the primary pulley 53b is transmitted to the secondary pulley 53d by pressing the winding transmission element 53e. Accordingly, in order to perform an upshift in a state where a high torque as in starting acceleration is input to the primary pulley 53b, a high primary pressure Pp must be supplied to the primary pulley 53b. Slip occurs between them.

  Therefore, in the TCU 43, at the time of starting acceleration, the vehicle speed V is set to a threshold vehicle speed Vo (for example, a vehicle speed at which lockup is started and about 25 to 30 [Km / h]) for determining the completion of acceleration. Until it reaches, the first speed of the A / T mode is selected as the start acceleration gear ratio, and the vehicle is allowed to travel at the first speed without upshifting.

  Specifically, the shift control at the time of start acceleration executed by the TCU 43 is processed according to the start acceleration control routine shown in FIG.

  In this routine, first, in step S1, the vehicle speed V and the accelerator opening AP are read, and in the subsequent step S2, it is determined whether or not the vehicle is to start based on the vehicle speed V and the accelerator opening AP.

  When the accelerator pedal opening AP is 0 [%] and the vehicle speed V is 0 [Km / h], it is determined that the vehicle is stopped, and when AP> 0 and V> 0, the acceleration after the start is started. It determines with a driving | operation and branches to step S3, respectively. On the other hand, if AP> 0 and V = 0, it is determined that the vehicle has started, and the process proceeds to step S4.

  In step S3, the vehicle speed V is compared with the determination vehicle speed Vo. If V ≦ Vo, it is determined that the vehicle is stopped or after acceleration, and the process proceeds to step S4 to continue the start preparation or start acceleration control. On the other hand, if V> Vo, it is determined that the start acceleration has been completed in the TCU 43, and the routine is exited. After the start acceleration control is completed, the accelerator opening AP and the mode switching determination opening APo are compared. If AP <APo, the CVT mode is selected as the shift mode, and the CVT mode shift map (FIG. 4). Shift control is executed according to (a). On the other hand, when AP ≧ APo, the A / T mode is selected as the shift mode, and the shift control is executed according to the A / T mode shift map (see FIG. 4B). Note that the processing in steps S2 and S3 described above corresponds to the starting acceleration detecting means of the present invention.

  Further, when it is determined that the vehicle is started or accelerated after the vehicle is started and the process proceeds from step S2 or step S3 to step S4, the A / T mode shift map is read in order to set the shift mode to the A / T mode. In step S5, the gear ratio is fixed at the first speed of the A / T mode shift map, and the routine is exited. The processes in steps S4 and S5 correspond to the start acceleration control means of the present invention.

  As a result, for example, if the driver turns on the ignition switch and operates the diesel engine 1 and then attempts to start by depressing the accelerator pedal, the transmission mode is automatically set to the A / T mode in step S4. In step S5, the gear ratio is fixed at the first speed in the A / T mode shift map, so that the vehicle speed V is increased in proportion to the turbine speed Nt without being immediately upshifted during start acceleration.

  As shown in FIG. 5, in the present embodiment, at the time of starting acceleration, the gear position is fixed at the first speed of the A / T mode shift map. Therefore, the vehicle speed V is changed to the turbine until the vehicle speed V reaches the determination vehicle speed Vo. It can be increased in proportion to the rotational speed Nt. On the other hand, conventionally, the CVT mode is selected as the speed change mode at the time of start acceleration, and the speed ratio is set on the basis of the CVT mode speed change map. Therefore, as shown by the alternate long and short dash line in FIG. When the vehicle speed reaches a predetermined vehicle speed (around 10 to 15 [Km / h]) immediately after that, it is automatically upshifted.

  After that, when the vehicle speed V exceeds the determination vehicle speed Vo, the shift control at the start acceleration by the above-described start acceleration control routine is completed, and in the drawing, the A / T mode is switched. Therefore, according to the A / T mode shift map, Shift control is executed.

  In this case, when the vehicle speed V exceeds the determination vehicle speed Vo, the A / T mode is selected as the shift mode and the upshift to the second speed is performed, compared to the start timing of the upshift in the CVT mode described above, Even with the same accelerator pedal depression amount, the upshift start timing can be delayed by time ta as shown in FIG.

  Changes in the turbine speed Nt, the primary pressure Pp, and the secondary pressure Ps at this time will be described with reference to a time chart shown in FIG.

  When the driver depresses the accelerator pedal and raises the engine speed Ne with respect to the stopped vehicle, the turbine speed Nt of the torque converter 52 is a speed corresponding to a predetermined torque amplification factor with respect to the engine speed Ne. Raised in ratio. At that time, as shown in FIG. 6B, the secondary pressure Ps of the CVT 53 increases rapidly to the maximum pressure, and prevents slipping between the secondary pulley 53d and the winding transmission element 53e at the start. On the other hand, the primary pressure Pp also rises to a pressure necessary for transmitting torque to the secondary pulley 53d via the winding transmission element 53e.

  The secondary pressure Ps once reaches the maximum pressure, and then gradually changes in a decreasing direction over time. On the other hand, since the upshift is performed by temporarily increasing the primary pressure Pp, as shown in FIG. 6B, the pressure is temporarily increased in both the CVT mode and the A / T mode. Since the primary pressure Pp at the time of upshifting is set in balance with the secondary pressure Ps, when the secondary pressure Ps is high, it is set higher accordingly.

  In the present embodiment, by fixing the speed change mode at the time of start acceleration to the first speed of the A / T mode, the speed change start timing can be delayed by the time ta compared to the CVT mode, and therefore, as shown in FIG. As described above, the secondary pressure Ps is decreased by ΔPs due to the gradual change of the time ta. As the secondary pressure Ps decreases, the primary pressure Pp during the upshift can be set lower by ΔPp1 in the A / T mode than in the CVT mode, as shown in FIG. In addition, the increase amount ΔPp2 of the primary pressure Pp in the A / T mode includes a pressure increase accompanying an increase in the shift speed in the multi-stage shift.

  As described above, in this embodiment, there are the CVT mode and the A / T mode as the speed change mode, and even when the speed change mode is automatically switched by the depression amount of the accelerator pedal, the speed change at the time of start acceleration is performed. Since the ratio is fixed to the first speed in the A / T mode, the shift start timing can be delayed by the time ta as compared with the shift start timing in the conventional CVT mode. As a result, the pressure increase of the primary pressure Pp can be set lower by ΔPp1 than in the conventional CVT mode, so the rated pressure is lowered, and the thickness of the case forming the primary pressure chamber 53f is reduced accordingly. For example, the structure can be simplified and the weight can be reduced. Further, the CVT 53 can be downsized by simplifying the structure and reducing the weight. Moreover, fuel consumption can be improved by weight reduction.

  The present invention is not limited to the above-described embodiment. For example, the switching between the CVT mode and the A / T mode may be selectively switched manually. At that time, the above-described start acceleration control means is applied when the CVT mode is selected as the shift mode at the start. Further, the start acceleration gear ratio in the CVT mode may be set to a gear ratio different from the first speed set in the A / T mode. Furthermore, the prime mover is not limited to a diesel engine with a turbo as long as it can generate a low rotation and high torque, and may be a gasoline engine.

  Further, the start acceleration determined in step S3 in FIG. 3 is not only the vehicle speed V but also the elapsed time after the start, the acceleration after the start, the change in the engine speed Ne after the start, the decrease in the primary pressure Pp, the accelerator opening. You may make it determine based on the change of degree AP, etc.

DESCRIPTION OF SYMBOLS 1 ... Diesel engine 33 ... Accelerator opening degree sensor 34 ... Vehicle speed sensor 43 ... Shift control unit 51 ... Automatic transmission 52 ... Torque converter 53b ... Primary pulley 53d ... Secondary pulley 53e ... Winding type transmission element 53f ... Primary pressure chamber 53g ... Secondary pressure chamber 61 ... turbine speed sensor 62 ... secondary speed sensor AP ... accelerator opening APo ... mode switching determination opening Ne ... engine speed Nt ... turbine speed Pp ... primary pressure Ps ... secondary pressure ta ... time V ... Vehicle speed Vo ... Judgment vehicle speed

Claims (4)

A continuously variable transmission capable of continuously changing the gear ratio;
The continuously variable transmission has a continuously variable transmission mode in which a gear ratio can be set continuously and a multi-speed transmission mode in which the gear ratio can be set in stages, and selectively switches between the gear modes. Switching means;
A vehicle shift control device comprising: a shift control unit that performs shift control of the continuously variable transmission based on the shift mode selected by the switching unit;
The shift control means includes
Start acceleration detection means for detecting the start of the vehicle or the acceleration operation after the start,
And a start acceleration control means for fixing a speed ratio of the continuously variable transmission to a predetermined speed ratio set in advance when the start acceleration detecting means determines that the vehicle is started or accelerated after starting. Shift control device. Accelerator opening selection means for detecting the accelerator opening;
Vehicle speed detecting means for detecting the vehicle speed;
The start acceleration detection means determines a start based on the vehicle speed detected by the vehicle speed detection means and the accelerator opening detected by the accelerator opening detection means, and further determines the vehicle speed and a preset acceleration end. The vehicle shift control device according to claim 1, wherein the end of acceleration is determined by comparing with a vehicle speed. The vehicular speed change control apparatus according to claim 1 or 2, wherein the predetermined speed change ratio is a maximum speed change ratio set in the multi-stage speed change mode. The switching means compares the accelerator opening detected by the accelerator opening detecting means with a preset mode switching determination opening, and if the accelerator opening is equal to or less than the mode switching determination opening, the steplessly 4. The vehicle according to claim 1, wherein a shift mode is selected, and the multi-stage shift mode is selected when the accelerator opening exceeds the mode switching determination opening. Shift control device.

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