Speed ratio control method and device for continuously variable transmission
First Claim
1. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine, comprising the steps of:
- computing an adaptation factor according to a function of an engine load component and time;
computing a target engine speed according to the adaptation factor; and
controlling said continuously variable transmission so that an engine speed becomes the target engine speed,said step of computing an adaption factor comprising computing the adaptation factor by recursively adding a value of a previous adaptation factor to a value related to time.
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Abstract
The invention improves the driveability of a vehicle by controlling a target engine speed according to an engine load and a vehicle running condition to ensure an actual engine speed. In controlling a speed ratio of a continuously variable transmission, an adaptation factor is used for deciding a target engine speed, the adaptation factor is determined according to constants, an average engine load and an average vehicle speed change quantity. Even when the average engine load changes because of fluctuation in an accelerator opening, various running modes can be decided by the adaptation factor depending upon both the average engine load and the average vehicle speed change quantity, thereby improving driveability upon changing speed of the continuously variable transmission.
51 Citations
60 Claims
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1. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine, comprising the steps of:
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computing an adaptation factor according to a function of an engine load component and time; computing a target engine speed according to the adaptation factor; and controlling said continuously variable transmission so that an engine speed becomes the target engine speed, said step of computing an adaption factor comprising computing the adaptation factor by recursively adding a value of a previous adaptation factor to a value related to time. - View Dependent Claims (3, 4)
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2. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine, comprising the steps of:
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computing an adaptation factor according to both an engine load component and a vehicle body change quantity component; computing a target engine speed according to the adaptation factor; and controlling the continuously variable transmission so that an engine speed becomes the target engine speed, the vehicle body change quantity component of the adaptation factor being set as a function of either one of an average vehicle speed change quantity or an average vehicle acceleration.
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5. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine comprising the steps of:
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computing an adaptation factor according to a function of an engine load component and time; computing a target engine speed according to the adaptation factor; and controlling said continuously variable transmission so that an engine speed becomes the target engine speed, when an engine load is larger than the engine load component of the adaptation factor, the engine load component is increased according to a difference between the engine load and the engine load component.
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6. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine comprising the steps of:
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computing an adaptation factor according to a function of an engine load component and time; computing a target engine speed according to the adaptation factor; and controlling said continuously variable transmission so that an engine speed becomes the target engine speed, when an engine load is smaller than the engine load component of the adaptation factor, the engine load component is decreased according to the engine load and the adaptation factor or according to the engine load and a speed ratio of the continuously variable transmission.
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7. A speed ratio control apparatus for feedback control of a speed ratio of a continuously variable transmission connected to an engine so that an actual engine speed corresponds with a target engine speed, the speed ratio control apparatus comprising:
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adaptation factor computing means for computing an adaptation factor according to a vehicle running condition; minimum target engine speed computing means for computing a minimum target engine speed according to a vehicle speed and the computed adaptation factor; maximum target engine speed computing means for computing a maximum target engine speed according to the vehicle speed, the computed adaptation factor, and an engine speed; target engine speed change quantity computing means for computing a target engine speed change quantity according to the vehicle speed and a vehicle speed change quantity; target engine speed computing means for computing a present target engine speed according to a previous target engine speed and the computed target engine speed change quantity; and speed ratio control means for controlling the speed ratio of the continuously variable transmission with feedback so that the actual engine speed corresponds with a target value wherein the present target engine speed is set to the target value when the present target engine speed falls within a range between the minimum target engine speed and the maximum target engine speed, the minimum target engine speed is set to the target value when the present target engine speed is lower than the minimum target engine speed, and the maximum target engine speed is set to the target value when the present target engine speed is higher than the maximum target engine speed.
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8. An adaptive speed ratio control apparatus for a continuously variable transmission of a vehicle having an engine, comprising:
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means for computing an adaptation factor according to a function of an engine load component and time; means for obtaining a target engine speed according to the adaptation factor; means for controlling the continuously variable transmission so that an engine speed becomes the target engine speed; means for determining when an engine load is larger than the engine load component of the adaptation faction; and means for increasing the engine load component according to a difference between the engine load and the engine load component. - View Dependent Claims (10, 11)
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9. An adaptive speed ratio control apparatus for a continuously variable transmission of a vehicle having an engine, comprising:
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means for computing an adaptation factor according to both an engine load component and a vehicle body change quantity component; means for obtaining a target engine speed according to the adaptation factor; and means for controlling the continuously variable transmission so that an engine speed becomes the target engine speed, the vehicle body change quantity component of the adaptation factor being a function of either one of average vehicle speed change quantity of an average acceleration quantity.
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12. An adaptive speed ratio control apparatus for a continuously variable transmission of a vehicle having an engine, comprising:
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means for computing an adaptation factor according to a function of an engine load component and time; means for obtaining a target engine speed according to the adaptation factor; means for controlling the continuously variable transmission so that an engine speed becomes the target engine speed; means for determining when an engine load is smaller than the engine load component of the adaptation factor; and means for decreasing the engine load component according to the engine load and the adaptation factor or according to the engine load and a speed ratio of the continuously variable transmission.
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13. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine comprising the steps of:
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computing an adaptation factor according to a function of an engine load component and time; computing a target engine speed according to the adaptation factor; and controlling said continuously variable transmission so that an engine speed becomes the target engine speed, said step of computing an adaptation factor comprising computing the adaptation factor
space="preserve" listing-type="equation">A=(A2-A1) (1-e.sup.-at)+A1wherein A is the adaptation factor, A2 is an adaptation factor upper limit, A1 is an adaptation factor lower limit, t is time and a is a constant. - View Dependent Claims (14, 15)
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16. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine, comprising the steps of:
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a) determining an engine load quantity, b) determining a vehicle body change quantity, c) computing an adaptation factor having an engine load component related to said engine load quantity and a vehicle body change component related to said vehicle body change quantity, d) computing a target engine speed according to said adaptation factor, and e) controlling the continuously variable transmission so that an engine speed becomes Said target engine speed. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An adaptive speed ratio control method for a continuously variable transmission of a vehicle having an engine, comprising the steps of:
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a) determining a vehicle body change quantity, b) computing an adaptation factor according to a vehicle body change component which is related to said vehicle body change quantity, c) computing a target engine speed according to the adaptation factor, and d) controlling the continuously variable transmission so that an engine speed becomes the target engine speed. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38)
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39. An adaptive speed ratio control method for a continuously variable transmission in a vehicle having an engine, the engine having at least a sport mode of operation with a relatively high engine output and a cruising mode of operation with a relatively low engine output, the adaptive speed ratio control method comprising the steps of:
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determining speed changes of said vehicle; determining accelerations of said vehicle; automatically switching said continuously variable transmission to said sport mode if said speed changes are relatively frequent or if said accelerations are relatively frequent; and automatically switching said continuously variable transmission to said cruising mode if said speed changes are relatively infrequent or if said accelerations are relatively infrequent. - View Dependent Claims (40, 41, 42)
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43. An adaptive speed ratio control apparatus for controlling a continuously variable transmission of a vehicle having an engine, comprising:
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means for determining an engine load quantity, means for determining a vehicle body change quantity, means for computing an adaptation factor having an engine load component related to said engine load quantity and a vehicle body change component related to said vehicle body change quantity, means for computing a target engine speed according to the adaptation factor, and control means for controlling the continuously variable transmission so that an engine speed becomes the target engine speed. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. An adaptive speed ratio control apparatus for a continuously variable transmission of a vehicle having an engine, comprising:
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means for determining a vehicle body change quantity, means for computing an adaptation factor according to a vehicle body change component which is related to said vehicle body change quantity, means for computing a target engine speed according to the adaptation factor, and control means for controlling the continuously variable transmission so that an engine speed becomes the target engine speed. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60)
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Specification