JP4136305B2 - Control device and control method for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device and a control method for an automatic transmission for a vehicle.
[0002]
[Prior art]
Conventionally, as a control method for a continuously variable automatic transmission (hereinafter referred to as CVT), as disclosed in, for example, Japanese Patent Laid-Open No. 63-57953, the CVT gear ratio is determined from the vehicle speed and the throttle opening. A method of performing control so as to coincide with the required target gear ratio is used.
[0003]
FIG. 9 is a diagram for explaining a conventional CVT shift schedule. FIG. 9A shows a normal mode shift schedule, and FIG. 9B shows a sport mode in which the engine speed is set higher than that in the normal mode. The shift schedule is shown. In FIG. 9, the vertical axis indicates the primary rotational speed Np (or engine rotational speed Ne), and the horizontal axis indicates the secondary rotational speed Ns (or vehicle speed V). Here, the primary rotation speed Np is the rotation speed of the input pulley of the CVT to which the driving force from the engine is input, and the secondary rotation speed Ns is the rotation of the output pulley of the CVT that transmits the output driving force to the drive wheels. Is a number. In FIG. 9, a straight line Tvo indicates the throttle opening. In the figure, the throttle opening Tvo is divided into five stages for convenience, the fully closed state is Level 1 and the fully open state is Level 5.
[0004]
In the conventional CVT control method, the primary rotational speed Np corresponding to the current throttle opening degree Tvo and the secondary rotational speed Ns is obtained based on the shift schedule shown in FIG. 9, and the CVT is matched with the primary rotational speed Np. To control.
[0005]
When CVT is in the normal mode, as shown in FIG. 9A, the gear ratio Np / Ns is represented by a region surrounded by A-B-C-D-A. In other words, the gear ratio Np / Ns can be changed steplessly within the A-B-C-D-A region. Further, when the CVT is in the sport mode, as shown in FIG. 9B, the speed ratio Np / Ns is represented by a region surrounded by A-B-C-E-F-A. In other words, the gear ratio Np / Ns can be changed steplessly within the A-B-C-E-F-A region. In this regard, as shown in FIG. 9A, the speed ratio Np / Ns is represented by a plurality of straight lines (oa, obs, oc, od) passing through the origin O, and the speed ratio This is different from a stepped automatic transmission in which Np / Ns can be changed only in steps. In the CVT shift schedule shown in FIG. 9, the straight line o-A-B indicates the portion with the largest speed ratio.
[0006]
[Problems to be solved by the invention]
However, since the conventional CVT control method does not consider the road gradient when determining the target gear ratio Np / Ns, the following problems arise.
[0007]
(1) Normally, the driver returns the accelerator pedal for the purpose of reducing the vehicle speed when the vehicle approaches a certain level of downhill. Therefore, according to the CVT shift schedule shown in FIG. 9 (a), if the operating point immediately before the vehicle approaches the downhill is point (a), the throttle opening is moved in the closing direction by returning the accelerator pedal. Then, the operating point moves to the (B) point. That is, the gear ratio Np / Ns moves to the top side. As a result, the engine brake becomes ineffective, the speed is increased against the driver's intention, and the operating point moves to the point (c). For this reason, the driver often wears the brake pad to reduce the vehicle speed and wears the brake pad, and the foot brake may not work.
[0008]
It is also possible to obtain sufficient engine braking by switching the shift schedule to the sport mode when the operating point moves to (c). That is, as shown in FIG. 9B, when the vehicle speed increases and the operating point moves to the point (c), when the driver actively switches the range from the normal mode to the sport mode, The operating point shifts from the point (c) to the point (d), the speed ratio Np / Ns increases, and a sufficient engine brake can be obtained. However, inexperienced drivers often cannot perform aggressive range switching.
[0009]
{Circle around (2)} When the uphill continues to some extent, it is necessary to increase the engine speed Ne by increasing the accelerator pedal to move the throttle opening Tvo in order to maintain the vehicle speed. If this is a steep climb, you will have to step up considerably. In this case, as shown in FIG. 9, the speed ratio Np / Ns gradually shifts to the low side at the same time as the depression of the accelerator pedal, but if the slope is steep, the range is changed from the normal mode to the sport mode. It is necessary to switch to. That is, even in the case of CVT, the driver needs to switch the range according to the slope of the road surface, which makes the driver feel bothersome.
[0010]
The present invention has been made on the basis of the above circumstances, and according to the road surface conditions, an engine brake suitable for the gradient is obtained on the down slope, and the vehicle driving force suitable for the slope is obtained on the up slope. It is an object of the present invention to provide an automatic transmission control device and control method for automatically controlling a gear ratio.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, an invention according to claim 1 is directed to an input-side rotating body to which driving force is transmitted from an engine of an automatic transmission mounted on an automobile, and transmitted driving force to driving wheels. A control device for an automatic transmission that changes a rotation speed ratio with an output-side rotator and controls a gear ratio of the automatic transmission,
A vehicle speed detector for detecting the vehicle speed of the automobile;
A road surface gradient estimation unit for estimating a road surface gradient during travel of the automobile;
A determination unit that determines whether or not the road gradient during traveling estimated by the road gradient estimation unit exceeds a preset threshold;
A vehicle speed setting unit for setting a target vehicle speed based on the vehicle speed detected by the vehicle speed detection unit when it is determined that the road gradient during traveling by the determination unit exceeds the threshold;
A control unit that controls the speed ratio so that the vehicle speed becomes the target vehicle speed set by the vehicle speed setting unit when it is determined by the determination unit that the road gradient during traveling exceeds a threshold; With
The road surface gradient estimation unit includes vehicle drive torque calculation means for calculating vehicle drive torque for driving the drive wheels output from the output side rotator,
Travel resistance torque calculating means for determining a travel resistance torque based on the vehicle speed detected by the vehicle speed detection unit;
Acceleration torque calculation means for obtaining acceleration of the automobile and obtaining acceleration torque based on the acceleration;
A gradient torque is obtained by subtracting the running resistance torque calculated by the running resistance torque calculating unit and the acceleration torque calculated by the acceleration torque calculating unit from the vehicle driving torque calculated by the vehicle driving torque calculating unit, and based on the gradient torque A slope calculating means for obtaining a slope of the road surface;
It is characterized by having.
[0012]
According to a second aspect of the present invention, in the first aspect of the invention, the vehicle speed setting unit is detected by the vehicle speed detection unit when it is determined by the determination unit that the running road surface gradient exceeds the threshold value. A value obtained by multiplying the vehicle speed by a coefficient corresponding to the vehicle speed is set as a target speed.
[0013]
According to a third aspect of the present invention, in the first aspect of the invention, the vehicle speed setting unit is detected by the vehicle speed detection unit when it is determined that the road surface gradient being traveled exceeds the threshold value by the determination unit. A value obtained by multiplying the vehicle speed by a coefficient corresponding to the road gradient during traveling estimated by the road gradient estimation unit is set as a target velocity.
[0014]
The invention according to claim 4 or claim 1, wherein the vehicle speed setting unit detects the vehicle speed detection unit when it is determined that the running road surface gradient exceeds the threshold value. A value obtained by multiplying the vehicle speed by a coefficient corresponding to the vehicle speed and a coefficient corresponding to the road surface gradient during traveling estimated by the road surface gradient estimation unit is set as a target speed.
[0015]
According to a fifth aspect of the present invention, in the first, second, third, or fourth aspect, the acceleration torque calculating means obtains the acceleration by differentiating the vehicle speed detected by the vehicle speed detecting unit with respect to time. To do.
[0016]
A sixth aspect of the invention is the invention according to the first, second, third, fourth, or fifth aspect, wherein the input side rotating body receives a driving force output from the engine via a torque converter. Yes,
The vehicle driving torque calculating means includes engine speed detecting means for detecting the engine speed,
Input rotational speed detection means for detecting the rotational speed of the input side rotating body;
Output rotational speed detection means for detecting the rotational speed of the output side rotating body;
A speed ratio calculating means for obtaining a speed ratio which is a ratio of an input rotating body rotational speed detected by the input rotating body detecting means and an output rotating body rotational speed detected by the output rotating body detecting means; and the input rotating body detecting means A slip ratio calculating means for calculating a ratio of the input rotating body rotational speed detected by the engine rotational speed detected by the engine rotational speed detecting means to obtain a slip ratio of the torque converter;
Torque ratio calculation means for obtaining a torque ratio according to the slip ratio calculated by the slip ratio calculation means from a map showing the relationship between the slip ratio of the torque converter prepared in advance and the torque ratio of pump torque and turbine torque; ,
Pump capacity coefficient calculating means for obtaining a pump capacity coefficient corresponding to the slip ratio calculated by the slip ratio calculating means from a map showing a relationship between a slip ratio of the torque converter and a pump capacity coefficient prepared in advance. ,
The engine speed detected by the engine speed detecting means, the speed ratio determined by the speed ratio detecting means, the torque ratio determined by the torque ratio calculating means, and the pump capacity coefficient determined by the pump capacity coefficient calculating means Based on the above, the wheel drive torque is calculated.
[0017]
The invention according to claim 7 is the number of revolutions of an input side rotator that transmits driving force from an engine and an output side rotator that transmits the output driving force to driving wheels in an automatic transmission mounted on an automobile. A control method of an automatic transmission for changing a ratio and controlling a gear ratio of the automatic transmission,
Detecting the vehicle speed of the automobile and the vehicle driving torque for driving the drive wheels output from the output-side rotator,
From the detected vehicle driving torque, the running resistance torque and acceleration torque obtained based on the detected vehicle speed are subtracted to obtain gradient torque, and the road surface gradient during running of the automobile is estimated based on the gradient torque,
It is determined whether the estimated road gradient during traveling exceeds a preset threshold value,
Based on the vehicle speed when it is determined that the estimated road surface gradient during traveling exceeds the threshold value, a target vehicle speed is set,
When it is determined that the estimated road gradient during traveling exceeds the threshold value, the speed ratio is controlled so that the vehicle speed becomes the set target vehicle speed. .
[0018]
According to the present invention, when the road gradient during traveling exceeds a predetermined threshold, the vehicle speed is set based on the vehicle speed when the road gradient during traveling exceeds the predetermined threshold. The gear ratio of the automatic transmission is controlled so as to match the target vehicle speed. As a result, an engine brake adapted to the gradient is automatically obtained when the vehicle is descending, and a vehicle driving force appropriate for the gradient can be automatically obtained when the vehicle is ascending.
[0019]
In the present invention, the vehicle speed when entering the hill is set by setting a value obtained by multiplying the vehicle speed when the road surface gradient during traveling exceeds a predetermined threshold value by a coefficient corresponding to the vehicle speed. When it is too fast, the vehicle speed while traveling on a slope can be maintained at an appropriate speed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a schematic block diagram showing an automobile drive system to which an automatic transmission control apparatus according to an embodiment of the present invention is applied.
[0022]
As shown in FIG. 1, an automobile drive system to which the present embodiment is applied includes an engine 1, a CVT 2 coupled to the output shaft of the engine 1, a drive wheel 8, and a drive that rotationally drives the drive wheel 8. A shaft 7, a differential gear 6 that transmits the driving force of the engine 1 extracted from the output side of the CVT 2 to the drive shaft 7, an intake pipe 11 that sends air into the engine 1, and an exhaust that guides exhaust gas from the engine 1 to the outside A pipe 14, a fuel injection valve 15 for injecting fuel into the cylinder of the engine 1, a hydraulic circuit 17 for operating the CVT 2, a transmission control valve 18 for controlling the hydraulic circuit 17, an engine control unit 30, and a CVT control unit 40 and a vehicle weight sensor 27 that detects a vehicle weight W provided on a suspension (not shown).
[0023]
The engine 1 is provided with a crank angle sensor 23 that detects a rotational speed Ne of a crankshaft that is an output shaft of the engine 1.
[0024]
The CVT 2 includes a torque converter 3 connected to the crankshaft of the engine 1 and a continuously variable transmission mechanism 4 connected to the output shaft of the torque converter 3.
[0025]
The torque converter 3 is provided via oil between the pump 3a directly connected to the crankshaft of the engine 1, the turbine 3b directly connected to the input shaft of the continuously variable transmission mechanism 4, and the pump 3a and the turbine 3b. And a stator 3c.
[0026]
The stepless speed change mechanism 4 includes a primary pulley 19 that receives the driving force from the torque converter 3, a secondary pulley 20 that transmits the driving force to the driving wheels 8, and a driving force that the primary pulley 19 receives to the secondary pulley 20. And a metal belt 9. In the stepless speed change mechanism 4 of this embodiment, the diameter of the primary pulley 19 is changed by the hydraulic circuit 17. As a result, the rotation speed ratio between the primary pulley 19 and the secondary pulley 20, that is, the gear ratio changes. The continuously variable transmission mechanism 4 includes a primary rotation sensor 29 that detects a primary rotation speed Np that is the rotation speed of the primary pulley 19 and a secondary rotation sensor 26 that detects a secondary rotation speed Ns that is the rotation speed of the secondary pulley 20. And are provided. The secondary rotation speed Ns is proportional to the vehicle speed.
[0027]
The intake pipe 11 is provided with an air cleaner 10 for purifying air, an idle speed valve 13 for adjusting the amount of air passing through the intake pipe 11, and the amount of air passing through the intake pipe 11 in accordance with the movement of an accelerator pedal (not shown). A throttle valve 12 for adjustment, an air flow sensor 21 for detecting the air amount Qa passing through the intake pipe 11, and a throttle opening sensor 22 for detecting the valve opening Tvo of the throttle valve 12 are provided. In the present embodiment, the throttle valve 12 is provided so as to be mechanically interlocked with the accelerator pedal. The operation amount of the accelerator pedal and the throttle opening degree Tvo are in a substantially one-to-one relationship, and when the operation amount of the accelerator pedal is 0, the throttle opening degree Tvo is also 0 (the throttle valve 12 is closed). Therefore, detecting the throttle opening Tvo indirectly detects the operation amount of the accelerator pedal. The intake pipe 11 is provided with a bypass pipe (not shown) so that the idling state can be maintained even when the throttle opening degree Tvo is 0, and air is slightly passed to the engine 1 through the bypass pipe. Supplied.
[0028]
As shown in FIG. 2, the engine control unit 30 includes a CPU 71 that executes various calculations, a ROM 72 that stores programs and various data for the CPU 71 to perform calculations, and a RAM 73 that temporarily stores data. An input / output interface circuit 75 that receives signals from various sensors and outputs signals to various valves, a LAN control circuit 76 that transmits and receives data to and from the AT control unit 40, and an engine control unit 30 And a bus 74 that connects the constituent devices so that signals can be transmitted and received between them. The engine control unit 30 is based on information from the airflow sensor 21, the throttle opening sensor 22, the crank angle sensor 23, and the AT control unit 40, or the fuel injection valve 15, the idle speed valve 13, or not shown. The ignition circuit is controlled.
[0029]
The AT control unit 40 controls the transmission operation valve 18 based on information from the primary rotation sensor 29, the secondary rotation sensor 26, the vehicle weight sensor 27, the AT oil temperature sensor 28, and the engine control unit 30. The hardware configuration of the AT control unit 40 is basically the same as the hardware configuration of the engine control unit 30 shown in FIG.
[0030]
FIG. 3 is a diagram functionally showing the configuration of the AT control unit 40. As shown in FIG. 3, the AT control unit 40 includes a road surface gradient estimation unit 41 that estimates a road surface gradient sin θ, a determination unit 100, a target vehicle speed determination unit 47 that determines a target vehicle speed, and a transmission operation. And a control unit 50 that controls the valve 18.
[0031]
The road surface gradient estimation unit 41 includes a torque calculation unit 42 that calculates a drive shaft torque To transmitted to the drive shaft 7 that drives the drive wheels 8, a travel resistance calculation unit 43 that calculates a flat ground travel resistance torque Tr, and a vehicle speed differentiation. It has the calculating part 44, the acceleration torque calculation part 45 which calculates acceleration resistance torque T (alpha), and the gradient calculation part 46. FIG.
[0032]
The torque calculation unit 42 uses the primary rotational speed Np sent from the primary rotational sensor 29, the secondary rotational speed Ns sent from the secondary rotational speed sensor 26, and the engine rotational speed Ne delayed from the crank angle sensor 23. The drive shaft torque To is calculated based on the information to be specified and the throttle opening Tvo delayed from the throttle opening sensor 22.
[0033]
FIG. 4 is a diagram functionally representing the configuration of the torque calculator 42. As shown in FIG. 4, the torque calculation unit 42 includes a division unit 56 that calculates the pulley gear ratio ip, a pump torque calculation unit 80 that calculates the pump torque Tp input to the pump 3 a of the torque converter 3, and the engine 1. An engine torque calculation unit 82 for calculating the engine torque Te, which is an output shaft torque of the engine, a selection unit 57, a multiplication unit 58, a multiplication unit 59, and a multiplication unit 83.
[0034]
The division unit 56 calculates the pulley speed ratio ip (= Np / Ns) by dividing the primary rotational speed Np by the secondary rotational speed Ns.
[0035]
The pump torque calculation unit 80 includes a division unit 57, a torque ratio calculation unit 52 that calculates a torque ratio t between an input (pump 3a) side torque and an output (turbine 3b) side torque of the torque converter 3, and a torque converter. 3 has a pump capacity coefficient calculation unit 53 that calculates a pump capacity coefficient Cp of 3, a multiplication unit 54, and a multiplication unit 55.
[0036]
The division unit 57 calculates the speed (slip) ratio e (= Np / Ne) of the torque converter 3 by dividing the primary rotational speed Np by the engine rotational speed Ne.
[0037]
The torque ratio calculation unit 52 uses a map showing the relationship between the speed ratio e and the torque ratio t of the torque converter 3 as shown in FIG. 7, and the torque ratio t corresponding to the speed ratio e calculated by the division unit 57. Ask for. Further, the pump capacity coefficient calculation unit 53 corresponds to the speed ratio e calculated by the division unit 57 using a map showing the relationship between the speed ratio e of the torque converter 3 and the pump capacity coefficient Cp as shown in FIG. The pump capacity coefficient Cp to be obtained is obtained.
[0038]
The multiplication unit 54 squares the engine speed Ne to calculate Ne2. The multiplier 55 multiplies the pump capacity coefficient Cp obtained by the pump capacity coefficient calculator 53 by Ne2 calculated by the multiplier 54. Thereby, the pump torque Tp (= Cp · Ne2) is calculated.
[0039]
The engine torque calculation unit 82 uses the map that shows the relationship among the engine speed Ne, the throttle opening Tvo, and the engine torque Te of the engine 1 as shown in FIG. 8 to detect the engine speed detected by the crank angle sensor 23. Ne and the engine torque Te corresponding to the throttle opening Tvo detected by the throttle opening sensor 22 are obtained. Here, in order to obtain the engine torque Te, a map showing the relationship among the engine speed Ne, the throttle opening degree Tvo, and the engine torque Te is used, but this value is used instead of the throttle opening degree in this map. The amount of air Qa passing through the intake pipe 11 detected by the correlated airflow sensor 21 or the amount of fuel injected from the fuel injection valve 15 controlled by the engine control unit 30 may be used.
[0040]
The selection unit 57 selects either the pump torque Tp calculated by the pump torque calculation unit 80 or the engine torque Te calculated by the engine torque calculation unit 82. The value selected here is used to calculate the drive shaft torque To. In this embodiment, the pump torque Tp is selected when the speed ratio e of the torque converter 3 calculated by the dividing unit 57 is smaller than a predetermined value (for example, around 0.9), and the engine torque Te is selected when larger. It is set to select. This is due to the following reason.
[0041]
When the speed ratio e of the torque converter 3 is large, the torque converter 3 may be locked up. In such a case, the pump capacity coefficient Cp cannot be obtained accurately from the speed ratio e. Incidentally, since the output shaft of the engine 1 and the pump 3a of the torque converter 3 are directly connected, the pump torque Tp is basically the same as the engine torque Te. However, when an air conditioner or the like is installed in a vehicle to which the present embodiment is applied and these are operating, the pump torque Tp is smaller than the engine torque Te by the amount of torque required to drive the air conditioner or the like. Become. Therefore, in this embodiment, when the speed ratio e of the torque converter 3 is smaller than a predetermined value, that is, the error included in the pump torque Tp calculated by the pump torque calculation unit 80 is more than the torque required to drive the air conditioner or the like. If the speed ratio e of the torque converter 3 is larger than a predetermined value, that is, the pump torque is calculated by using the pump torque Tp calculated by the pump torque calculation unit 80. When it is considered that the error included in the pump torque Tp calculated by the calculation unit 80 is larger than the torque required to drive the air conditioner or the like, the drive shaft torque is calculated using the engine torque Te calculated by the engine torque calculation unit 82. To is calculated.
[0042]
The multiplication unit 58 multiplies the torque ratio t of the torque converter 3 obtained by the torque ratio calculation unit 52 by the pump torque Tp or the engine torque Te selected by the selection unit 57. Thereby, the turbine torque Tt (= Tp · t or Te · t) output from the turbine 3b of the torque converter 3 is calculated. This turbine torque Tt corresponds to the input torque of CVT2.
[0043]
The multiplier 59 multiplies the turbine torque Tt calculated by the multiplier 58 by the speed ratio ip calculated by the multiplier 56. Thereby, the output torque of CVT2 is calculated.
[0044]
Multiplier 83 multiplies the output torque of CVT2 calculated by multiplier 59 by final reduction ratio if of CVT2. As a result, the drive shaft torque To (= Tt · ip · if) is obtained.
[0045]
The travel resistance calculation unit 43 calculates the flat ground travel resistance torque Tr based on the secondary rotation speed Ns sent from the secondary rotation sensor 26 and the vehicle weight W sent from the vehicle weight sensor 27. The flat ground running resistance torque Tr is expressed by the following equation.
Tr = (μr · W + ka · V2) · Rt
Here, μr is a rolling friction coefficient of the tire, ka is an air resistance coefficient, Rt is a moving radius of the tire, and V is a vehicle speed. The vehicle speed V has a correlation with the secondary rotational speed Ns and is a value determined by the secondary rotational speed Ns. Here, the vehicle weight sensor 27 is provided to obtain the vehicle weight W. However, for a passenger car or the like in which the change in the vehicle weight W is small, instead of detecting the vehicle weight W by the vehicle weight sensor 27, the passenger vehicle Standard vehicle weight, for example, the weight of two passengers may be used. Further, instead of detecting the vehicle weight W by the vehicle weight sensor 27, the vehicle speed V at one time and the vehicle speed V at another time are obtained on the condition that the road gradient θ and the drive shaft torque To are not changing. The vehicle weight W may be estimated from this change.
[0046]
The vehicle speed differential calculation unit 44 obtains the acceleration α by time-differentiating the vehicle speed V determined by the secondary rotational speed Ns. The acceleration torque calculation unit 45 calculates the acceleration resistance torque Tα based on the acceleration α obtained by the vehicle speed differentiation calculation unit 44 and the vehicle weight W sent from the vehicle weight sensor 27. The acceleration resistance torque Tα is expressed by the following equation.
Tα = (W + Wk) · α · Rt / g
Here, Wk is the rotational inertia weight, Rt is the tire moving radius, and g is the gravitational acceleration. Here, the secondary rotational speed detected by the secondary rotation sensor 26 is time-differentiated to obtain the acceleration. However, an acceleration sensor may be provided on the vehicle body to obtain the acceleration directly.
[0047]
The gradient calculating unit 46 includes a driving shaft torque To calculated by the torque calculating unit 46, a flat ground traveling resistance torque Tr calculated by the traveling resistance calculating unit 43, an acceleration resistance torque Tα calculated by the acceleration resistance torque calculating unit 45, and a vehicle weight sensor. On the basis of the vehicle weight W sent from the vehicle 27, the road surface gradient sin θ during traveling is calculated.
[0048]
FIG. 5 is a diagram functionally illustrating the configuration of the gradient calculation unit 46. There is a relationship expressed by the following equation among the drive shaft torque To, the flat running resistance torque Tr, the acceleration resistance torque Tα, and the road surface gradient torque Tθ.
To = Tr + Tα + Tθ
Therefore, as shown in FIG. 5, the gradient calculation unit 46 of the present embodiment subtracts the flat ground running resistance torque Tr by the subtraction unit 46a from the drive shaft torque To, and then subtracts the acceleration resistance torque α by the subtraction unit 46b. ing. Thereby, the road surface gradient torque Tθ during traveling is calculated.
[0049]
The road surface gradient torque Tθ is expressed by the following equation.
Tθ = W · sinθ · Rt
Therefore, in the gradient calculation unit 46 of the present embodiment, as shown in FIG. 5, the vehicle weight W sent from the vehicle weight sensor 27 by the multiplication unit 46c is multiplied by the tire moving radius Rt, and the multiplication unit 46d multiplies the vehicle weight W. The road gradient sin θ during traveling is calculated by dividing the road gradient torque Tθ calculated by the unit 46b by W · Rt calculated by the multiplication unit 46c. When the calculated sin θ is positive, it indicates that the traveling road surface is an uphill, and when it is negative, it indicates a downhill.
[0050]
In the determination unit 100, the absolute value of the running road surface gradient sin θ estimated by the road surface gradient estimating unit 41 exceeds a preset threshold value (for example, | sin3.5 ° |, equivalent to about 6% gradient). It is determined whether or not. If the threshold value is exceeded, a signal is output to the target vehicle speed determination unit 47. The determination unit 100 is provided with a sign determination unit that determines the sign of sin θ sent from the road surface gradient estimation unit 41, and the road surface that is running depends on whether the determined sign is positive or negative. Different threshold values may be used depending on whether it is an uphill or a downhill.
[0051]
While the signal is input from the determination unit 100, the target vehicle speed determination unit 47 is based on the road surface gradient sin θ calculated by the gradient calculation unit 46 and the secondary rotation speed Ns sent from the secondary rotation sensor 26. The rotation speed Nst is determined. As described above, since the secondary rotational speed Ns is proportional to the vehicle speed, the target vehicle speed is specified by the target secondary rotational speed Nst.
[0052]
The target vehicle speed determination unit 47 first obtains the secondary rotational speed Nsa at the start of input of a signal from the determination unit 100, that is, when the absolute value of the running road surface gradient sin θ exceeds the threshold value. Next, the target secondary rotational speed Nst is obtained based on the secondary rotational speed Nsa. The target secondary rotation speed Nsa is expressed by the following equation.
Nst = k · Nsa
Here, k is a constant determined by the secondary rotational speed Nsa, and decreases as the secondary rotational speed Nsa increases. In the present embodiment, 0 <k ≦ 1 is set.
[0053]
As shown in FIG. 3, the control unit 50 includes a target speed ratio calculation unit 48 and a speed change operation command output unit 49.
[0054]
When the determination unit 100 determines that the absolute value of the running road surface gradient sin θ exceeds the threshold value, that is, the target vehicle speed determination unit 47 determines that the target secondary speed Nst is the target gear ratio calculation unit 48. If it is calculated, the target gear ratio ipt (= Np / Nst) is obtained based on the target secondary rotation speed Nst and the current primary rotation speed Np sent from the primary rotation sensor 29. When the determination unit 100 determines that the absolute value of the running road surface gradient sin θ does not exceed the threshold value, that is, the target secondary speed Nst is calculated by the target vehicle speed determination unit 47. If not, a general CVT shift control method as described in the prior art is used. First, based on the shift schedule shown in FIG. 9, the target primary speed corresponding to the current secondary rotation speed Ns sent from the secondary rotation sensor 26 and the current throttle opening degree Tvo sent from the throttle opening degree sensor 22. The number of revolutions Npt is obtained. Next, a target gear ratio ipt (= Npt / Ns) is obtained from the target primary rotational speed Npt and the current secondary rotational speed Ns.
[0055]
The transmission operation command output unit 49 determines the operation amount of the transmission ratio control valve 18 based on the target transmission ratio ipt calculated by the target transmission ratio calculation unit 48 and operates the transmission ratio control valve 18. As a result, the diameter of the primary pulley 19 of the CVT 2 is changed by the hydraulic circuit 17, and the gear ratio is controlled to become the target gear ratio ipt.
[0056]
Next, the operation of the AT controller 40 will be described with reference to FIG. FIG. 6 is a flowchart for explaining the operation of the AT controller 40.
[0057]
First, in step 101, it is determined whether or not the absolute value of the traveling road surface gradient sin θ sent from the road surface gradient estimating unit 41 is larger than a threshold value stored in advance in a memory. When it is determined that the road surface gradient sin θ during traveling is larger than the threshold value, the process proceeds to step 102 to determine whether or not the flag is zero. Here, if the flag is 0, it means that the running road surface gradient θ has exceeded the threshold value for the first time, and if the flag is 1, the running road surface gradient θ has already exceeded the threshold value. Means.
[0058]
If it is determined in step 102 that the flag is 0, the process proceeds to step 103, where the secondary value when the absolute value of the running road surface gradient sin θ sent from the secondary rotation sensor 26 exceeds the threshold value is transferred. Based on the rotational speed Nsa, the target secondary rotational speed Nst is obtained and stored in the memory. Next, the flag is set to 1 (step 104), and then the process proceeds to step 105. On the other hand, if it is determined in block 102 that the flag is not 0, the process skips steps 103 and 104 and proceeds to block 105.
[0059]
Next, at block 105, a target speed ratio ipt is calculated based on the current primary speed Np sent from the primary speed sensor 29 and the target secondary speed Nsa, and the CVT2 makes this target speed ratio ipt. Control to be
[0060]
The processing from step 102 to step 105 is repeated until it is determined in step 101 that the absolute value of the road surface gradient sin θ during traveling is equal to or less than the threshold value. If it is determined in step 101 that the absolute value of the road surface gradient sin θ during traveling is equal to or less than the threshold value, the flag is reset to 0 (step 106), and the flow shown in FIG.
[0061]
In the present embodiment, when the absolute value of the road gradient sin θ during traveling exceeds a preset threshold value, the absolute value of the road gradient sin θ during traveling exceeds the threshold value. Based on the detected secondary rotational speed Nsa, the target secondary rotational speed Nst is set. The gear ratio of the CVT is controlled so that the secondary rotational speed Ns of the CVT 2 becomes the target secondary rotational speed Nst. Therefore, according to the present embodiment, the vehicle speed while traveling on a hill can be maintained at a speed determined according to the vehicle speed at the time of entering the hill, so that an engine brake that matches the gradient is automatically obtained on a downward slope. In addition, when the vehicle is going uphill, it is possible to automatically obtain a vehicle driving force appropriate to the slope.
[0062]
In the present embodiment, the target value obtained by multiplying the secondary rotational speed Nsa detected when the absolute value of the road surface gradient sin θ during traveling exceeds a threshold value by a coefficient k corresponding to the secondary rotational speed Nsa is used as the target. The secondary rotational speed Nst is used. Therefore, according to the present embodiment, when the approach speed to the hill is too fast, the vehicle speed while traveling on the hill can be maintained at an appropriate speed.
[0063]
Further, in the present embodiment, the vehicle drive torque To is obtained based on the engine speed Ne, the primary speed Np, and the secondary speed Ns, and the running resistance is determined based on the secondary speed Ns and the vehicle weight W. Torque Tr and acceleration torque Tα are obtained. Then, the running resistance torque Tr and the acceleration torque Tα are subtracted from the vehicle driving torque To to obtain the gradient torque Tθ, and the road surface gradient sin θ is obtained based on the gradient torque Tθ. Here, the primary rotation speed Np and the secondary rotation speed Ns are information necessary for control of the automatic transmission regardless of the stepped transmission and the continuously variable transmission. The engine speed Ne is normally provided to a driver or the like as one piece of information indicating the state of the vehicle. Further, although the vehicle weight W may be detected by providing a sensor, it can be set in advance in a passenger car or the like with little change in vehicle weight. Thus, according to the present embodiment, it is possible to estimate the road surface gradient by effectively using information indicating the state of the vehicle that has been used conventionally. That is, in this embodiment, it is not necessary to provide a special sensor (for example, a sensor for detecting the front / rear inclination of the vehicle) for detecting the road surface gradient.
[0064]
In addition, this invention is not limited to said embodiment, A various deformation | transformation is possible within the range of the summary. For example, in the above embodiment, when the absolute value of the road gradient sin θ during traveling is larger than the threshold value, the detection is performed when the absolute value of the road gradient sin θ during traveling exceeds the threshold value. A value obtained by multiplying the secondary rotational speed Nsa by a coefficient corresponding to the secondary rotational speed Nsa is set as the target secondary rotational speed Nst. However, the present invention is not limited to this.
[0065]
For example, when the absolute value of the road gradient sin θ during traveling is larger than a threshold value, the secondary rotational speed Nsa detected when the absolute value of the road gradient sin θ during traveling exceeds the threshold value is used. Alternatively, a value obtained by multiplying the coefficient q according to the absolute value of the road surface gradient sin θ currently traveling may be set as the target secondary rotation speed Nst. Here, the coefficient q is preferably set so as to decrease as the gradient becomes steep, and so that 0 <q ≦ 1. In this case, the vehicle speed can be controlled in accordance with the change in the road surface gradient that is currently running. Further, when the slope of the slope is steep, the vehicle speed while traveling on the slope can be maintained at an appropriate speed.
[0066]
Further, for example, when the absolute value of the road gradient sin θ during traveling is larger than the threshold value, the secondary rotational speed detected when the absolute value of the road gradient sin θ during traveling exceeds the threshold value. A value obtained by multiplying Nsa by a coefficient corresponding to the secondary rotational speed Nsa and a coefficient corresponding to the absolute value of the road surface gradient sinθ currently traveling may be set as the target secondary rotational speed Nst. In this case, the vehicle speed can be controlled in accordance with the vehicle speed at the time of entering the hill and the change in the road surface gradient during the current traveling.
[0067]
In the above embodiment, the CVT shift control is described. However, the present invention can be applied to the shift control of an automatic transmission regardless of whether it is stepped or stepless.
[0068]
【The invention's effect】
As described above, according to the present invention, when the vehicle is traveling, an engine brake corresponding to the gradient is automatically obtained when the vehicle is descending, and an appropriate vehicle driving force with respect to the gradient is obtained by the driver. It can be obtained automatically without performing the range switching by itself.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing an automobile drive system to which an automatic transmission control apparatus according to an embodiment of the present invention is applied.
FIG. 2 is a diagram showing a hardware configuration of an engine control unit.
FIG. 3 is a diagram functionally showing the configuration of an AT control unit.
FIG. 4 is a diagram functionally representing a configuration of a torque calculation unit.
FIG. 5 is a diagram functionally representing a configuration of a gradient calculation unit.
FIG. 6 is a flowchart for explaining the operation of the AT controller.
FIG. 7 is a diagram showing a relationship between a speed ratio e, a capacity coefficient Cp, and a torque ratio t.
FIG. 8 is a diagram showing a relationship among an engine speed Ne, an engine torque Te, and a throttle opening degree Tvo.
FIG. 9 is a diagram showing a shift schedule of a conventional automatic transmission.
[Explanation of symbols]
1 engine
2 CVT
3 Torque converter
4 Stepless transmission mechanism
6 Differential gear
7 Drive shaft
8 Drive wheels
17 Hydraulic circuit
18 Transmission control valve
21 Air flow sensor
22 Throttle opening sensor
23 Crank angle sensor
26 Secondary rotation sensor
27 Vehicle weight sensor
29 Primary rotation sensor
30 Engine control unit
40 AT control unit
41 Road slope estimation part
42 Torque calculator
43 Running resistance calculator
44 Vehicle speed differential calculation unit
45 Acceleration torque calculator
46 Gradient calculator
47 Target vehicle speed setting section
48 target gear ratio calculation unit
49 Shifting operation command output section
50 Control unit
100 judgment part

Claims (8)

A control device for an automatic transmission for controlling a gear ratio of an automatic transmission mounted on an automobile,
A vehicle speed detector for detecting the vehicle speed of the automobile;
A road surface gradient estimation unit for estimating a road surface gradient during travel of the automobile;
A determination unit for determining whether or not the road surface gradient during traveling estimated by the road surface gradient estimation unit exceeds a preset positive value ;
A control unit for controlling the gear ratio,
The road surface gradient estimation unit
Vehicle driving torque calculating means for calculating vehicle driving torque for driving the driving wheels of the automobile;
Based on the vehicle speed detected by the vehicle speed detection unit and the weight of the automobile, running resistance torque calculating means for obtaining a flat ground running resistance torque of the automobile;
Acceleration torque calculating means for determining acceleration of the vehicle speed and determining acceleration resistance torque of the vehicle based on the acceleration and the weight of the vehicle;
The gradient torque is obtained by subtracting the flat ground running resistance torque calculated by the running resistance torque calculating means and the acceleration resistance torque calculated by the acceleration torque calculating means from the vehicle driving torque calculated by the vehicle driving torque calculating means, and calculating the gradient torque. A slope calculating means for obtaining the road surface slope based on,
The vehicle driving torque calculating means includes
Engine torque calculating means for calculating an engine torque that is an output shaft torque of the engine based on the number of revolutions of the engine of the automobile and the fuel injection amount of the fuel injection valve;
A pump torque calculating means for calculating a pump torque input to a pump (input side) of a torque converter disposed between the engine and the automatic transmission and transmitting an output shaft torque of the engine to the automatic transmission. When,
When the slip ratio, which is the ratio of the rotational speed of the input side rotating body of the automatic transmission that receives the driving torque from the torque converter and the rotational speed of the engine, is smaller than a predetermined value, it is calculated by the pump torque calculating means. Selection means for selecting a pump torque, selecting the engine torque calculated by the engine torque calculation means if large, and outputting the selected torque as the vehicle driving torque to the control unit;
The control unit determines that the road gradient during traveling exceeds the threshold when the determination unit determines that the running road gradient exceeds the threshold. Sometimes, a target secondary rotational speed is calculated from the secondary rotational speed detected by a secondary pulley rotation sensor attached to the automatic transmission, and the target gear ratio is calculated using the target secondary rotational speed and the current primary rotational speed. If the speed ratio is controlled so as to be the target speed ratio, and the road surface gradient during traveling is determined not to exceed the threshold value, the speed ratio is controlled based on a predetermined speed change schedule. And controlling the speed ratio so that the target speed ratio is set based on the current vehicle speed and throttle opening. A control device for an automatic transmission for controlling a gear ratio of an automatic transmission mounted on an automobile,
A vehicle speed detector for detecting the vehicle speed of the automobile;
A road surface gradient estimation unit for estimating a road surface gradient during travel of the automobile;
A control unit for controlling the gear ratio,
The road surface gradient estimation unit
Vehicle driving torque calculation means for calculating vehicle driving torque for driving the driving wheels of the automobile based on the rotational speed of the engine of the automobile and the fuel injection amount of the fuel injection valve;
Based on the vehicle speed detected by the vehicle speed detection unit and the weight of the automobile, running resistance torque calculating means for obtaining a flat ground running resistance torque of the automobile;
Acceleration torque calculating means for determining acceleration of the vehicle speed and determining acceleration resistance torque of the vehicle based on the acceleration and the weight of the vehicle;
The gradient torque is obtained by subtracting the flat ground running resistance torque calculated by the running resistance torque calculating means and the acceleration resistance torque calculated by the acceleration torque calculating means from the vehicle driving torque calculated by the vehicle driving torque calculating means, and calculating the gradient torque. A slope calculating means for obtaining the road surface slope based on,
When it is determined that the traveling road surface gradient estimated by the road surface gradient estimation unit exceeds a preset positive value , the control unit is configured to connect a secondary pulley attached to the automatic transmission. The target secondary rotational speed is obtained by calculation from the secondary rotational speed detected by the rotation sensor, a target gear ratio is obtained using the target secondary rotational speed and the current primary rotational speed, and the speed change is performed so that the target gear ratio is obtained. A control device for an automatic transmission, characterized by controlling a ratio. A control device for an automatic transmission according to claim 1 or 2,
When the determination unit determines that the traveling road surface gradient exceeds the threshold value, the control unit detects the secondary rotation speed detected by a rotation sensor of a secondary pulley attached to the automatic transmission. A control device for an automatic transmission, wherein a value obtained by multiplying a coefficient corresponding to the secondary rotational speed is set as the target secondary rotational speed. A control device for an automatic transmission according to claim 1 or 2,
When the determination unit determines that the traveling road surface gradient exceeds the threshold value, the control unit detects the secondary rotation speed detected by a rotation sensor of a secondary pulley attached to the automatic transmission. A control device for an automatic transmission, wherein a value obtained by multiplying a coefficient according to a road surface gradient during traveling estimated by the road surface gradient estimation unit is set as the target secondary rotational speed. A control device for an automatic transmission according to claim 1 or 2,
When the determination unit determines that the traveling road surface gradient exceeds the threshold value, the control unit detects a secondary rotation speed detected by a rotation sensor of a secondary pulley attached to the automatic transmission. A value obtained by multiplying a coefficient according to the secondary rotational speed by a coefficient according to the road surface gradient during traveling estimated by the road surface gradient estimation unit is set as the target secondary rotational speed. Control device. A control device for an automatic transmission according to any one of claims 1 to 5,
The control device for an automatic transmission, wherein the acceleration torque calculation means obtains the acceleration of the automobile by differentiating the vehicle speed detected by the vehicle speed detection unit with respect to time. An automatic transmission control method for controlling a transmission ratio of an automatic transmission mounted on an automobile,
The engine torque, which is the output shaft torque of the engine, is calculated based on the rotational speed of the engine of the automobile and the fuel injection amount of the fuel injection valve, and is arranged between the engine and the automatic transmission, The torque converter that transmits the output shaft torque of the motor to the automatic transmission calculates the pump torque input to the pump (input side), and from the torque converter as the vehicle drive torque for driving the drive wheels of the automobile The pump torque is selected when the slip ratio, which is the ratio of the rotational speed of the input side rotating body of the automatic transmission and the rotational speed of the engine that receives the driving torque of the engine, is smaller than a predetermined value, and the engine torque when the slip ratio is larger Select the engine torque calculated by the calculation means,
Based on the vehicle speed and weight of the vehicle, to calculate the flat land running resistance torque of the vehicle,
Obtain the acceleration of the vehicle speed, calculate the acceleration resistance torque of the vehicle based on the acceleration and the weight of the vehicle,
Calculate the gradient torque by subtracting the calculated flat ground running resistance torque and acceleration resistance torque from the calculated vehicle driving torque, and estimate the road surface gradient during running of the vehicle based on the gradient torque,
Determine whether the estimated road slope exceeds a preset positive value threshold,
When it is determined that the estimated road surface gradient exceeds the threshold value, the rotation of the secondary pulley attached to the automatic transmission is determined when the road surface gradient is determined to exceed the threshold value. A target secondary rotational speed is obtained by calculation from the secondary rotational speed detected by the sensor, a target gear ratio is obtained using the target secondary rotational speed and the current primary rotational speed, and the speed ratio is set so as to be the target gear ratio. On the other hand, if it is determined that the road surface gradient does not exceed the threshold value, the target gear ratio is set based on the current vehicle speed and the throttle opening based on a predetermined shift schedule. And a control method for the automatic transmission, wherein the transmission ratio is controlled. An automatic transmission control method for controlling a transmission ratio of an automatic transmission mounted on an automobile,
Based on the number of revolutions of the engine of the automobile and the fuel injection amount of the fuel injection valve, a vehicle driving torque for driving the driving wheels of the automobile is calculated,
Based on the vehicle speed and weight of the vehicle, to calculate the flat land running resistance torque of the vehicle,
Obtain the acceleration of the vehicle speed, calculate the acceleration resistance torque of the vehicle based on the acceleration and the weight of the vehicle,
The slope torque is obtained by subtracting the flat ground running resistance torque and the acceleration resistance torque calculated from the calculated vehicle driving torque, and the road surface gradient is estimated based on the gradient torque.
When it is determined that the estimated road gradient during traveling exceeds a predetermined positive threshold value, the target is determined from the secondary rotational speed detected by the rotational sensor of the secondary pulley attached to the automatic transmission. An automatic transmission characterized in that a secondary speed is obtained by calculation, a target speed ratio is obtained using the target secondary speed and the current primary speed, and the speed ratio is controlled to be the target speed ratio. How to control the machine.

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