Constant speed control method for vehicle on inclined road

• US 20050038590A1
• Filed: 08/11/2004
• Published: 02/17/2005
• Est. Priority Date: 08/11/2003
• Status: Active Grant

• Current Assignee: Kai Motors Corporation (Hyundai Motor Group)
• Original Assignee: Kai Motors Corporation (Hyundai Motor Group)
• Inventors: Jung, Kil-Young
• Granted Patent: US 7,212,904 B2
• Time in Patent Office: Days
• US Class Current: 701/93
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: F02D 2200/0404 Throttle position
• CPC Class Codes: F02D 2200/702 Road conditions
• CPC Class Codes: F02D 29/02 peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: F02D 31/002 controlling air supply
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18

Abstract

A constant speed control method for a vehicle on an inclined road allows a constant speed control allowance to be one mile per hour on a flat road and two miles per hour on an inclined surface. If the vehicle speed decelerates two or more times of 1.5 miles per hour or more compared to the preset speed, the vehicle is assumed to be on a slope. A control system is performed by changing the constant speed control allowance from one mile per hour to two miles per hour. If the vehicle speed is within the allowance for 20 seconds, the control system on the inclined road is released. Thus, engine noise according to the frequent change of the T.P.S. value is prevented in advance and frequent gearshifts due to the rapid increment of the T.P.S. value is also prevented, resulting in a stable constant driving speed.

Claims

1. A constant speed control method for a vehicle, comprising:

detecting whether a counted value of a counter (C) is two after clearing a counted value of said counter to zero, wherein said counted value indicates the number of times a vehicle speed accelerates or decelerates more than or equal to 1.5 miles per hour compared to a preset speed (S) set by the user;

executing the vehicle to drive at a constant driving speed set for a flat road surface if said counted value of said counter is not equal to two, and detecting whether an actual vehicle speed (R) is greater than said preset speed (S);

detecting whether a speed differential value (M) is smaller than a constant speed control allowance on a flat road surface (A), wherein said speed differential value (M) is calculated by an absolute value of subtraction of said actual vehicle speed (R) from said preset speed (S) under the condition of S<

R;

detecting whether said speed differential value (M) is less than 1.5 miles per hour if M is greater than or equal to A;

adding one to the counted value of said counter if M≧

1.5 miles per hour, decreasing a Throttle Position Sensor (T.P.S.) value like the condition under M<

1.5 miles per hour, and returning to the step of detecting whether the counted value of said counter is two;

maintaining a constant speed driving mode on the flat road surface when said preset speed (S) is neither less nor greater than said actual vehicle speed (R) and the subtraction between said preset speed (S) and actual vehicle speed (R) is assumed to be zero, and if said actual vehicle speed (R) is slower than said preset speed (S), then detecting whether said speed differential value (M) is less than said constant speed control allowance on a flat road surface (A), wherein said speed differential value (M) is calculated by deducting said actual vehicle speed (R) from said preset speed (S);

detecting whether said speed differential value (M) is less than 1.5 miles per hour if M is not smaller than A, and if said speed differential value (M) is greater than or equal to 1.5 miles per hour, increasing said T.P.S. value after increasing the counted value of said counter by one, and returning to the step of detecting whether the counted value of said counter is two;

executing a constant speed driving mode on an inclined road if the counted value of said counter is two, and if said speed differential value (M) is less than a constant speed control allowance on the inclined road (B) for 20 seconds or more, then returning to said constant speed driving mode on a flat road surface, and if the state of M<

B is maintained for less than 20 seconds, then detecting whether said preset speed (S) is less than said actual vehicle speed (R) wherein said speed differential value (M) is determined by said preset speed estimated by the user and said actual vehicle speed;

determining whether said actual vehicle speed (R) is faster than said preset speed (S), and if so, calculating said speed differential value (M) by using an absolute value of the subtraction between said preset speed and said actual vehicle speed (S−

R), and then detecting whether the calculated speed differential value (M) is smaller than said constant speed control allowance on a flat road surface (A);

maintaining the operation of the timer if M<

A;

however if M≧

A, then whether said speed differential value (M) is smaller than said constant speed control allowance on the inclined road (B) is detected;

returning to the initial step of constant driving speed on the inclined road after reducing said T.P.S. value and clearing the counted value of said counter to be zero, if said speed differential value (M) is greater than or equal to said constant speed control allowance on the inclined road (B);

maintaining operation of the timer when said preset speed (S) is neither less nor greater than said actual vehicle speed (R) and the subtraction between said preset speed (S) and said actual vehicle speed (R) is assumed to be zero and detecting whether said speed differential value (M) is smaller than said constant speed control allowance on a flat road surface (A) only if said actual vehicle speed is slower than said preset speed; and

detecting whether said speed differential value (M) is less than said constant speed control allowance on the inclined road (B) if M is not smaller than A, and if said speed differential value is less than B, then returning to the constant speed driving mode on the inclined road, however, if said speed differential value (M) is greater than or equal to B, increasing said T.P.S. value, setting the counted value of said timer to be zero, and returning to the initial step of constant driving speed on the inclined road.

2. A constant speed control method for a vehicle, comprising the steps of:

determining whether a speed differential value between an actual vehicle speed and a preset speed estimated by a user is higher than a predetermined standard value;

determining that the vehicle is being driven on an inclined road if a number of times said speed differential value exceeds said preset standard value is greater than or equal to a predetermined value; and

executing a constant speed driving mode on the inclined road by applying a constant speed control allowance having a larger value than that of a constant speed control allowance on a flat road surface if the vehicle is determined to be driven on the inclined road.

3. The method as defined in claim 2, wherein said standard value is larger than said constant speed control allowance on a flat road surface.

4. The method as defined in claim 3, wherein said constant speed control allowance on the inclined road is larger than said standard value.

5. The method as defined in claim 2, wherein if the vehicle is determined to be driven on the inclined road and said speed differential value of said preset speed and said actual vehicle speed is smaller than said constant speed control allowance on the inclined road for more than or equal to 20 seconds, then said constant speed driving on the inclined road is released.

6. A computer program product for use in conjunction with a computer system, the computer program product comprising a computer readable storage medium and a computer program mechanism embedded therein, the computer program mechanism comprising:

instructions for determining a differential between an actual vehicle speed and a preset speed;

instructions for counting a number of times the differential exceeds a predetermined standard value; and

instructions for executing an inclined surface constant speed driving mode wherein a larger constant speed control allowance is applied than a constant speed control allowance for a substantially flat surface if the counted number is greater than an predetermined value.

7. The computer program product of claim 6, further comprising instructions wherein if the speed differential value is smaller than the inclined surface constant speed driving mode for not less than about 20 seconds, the inclined surface constant speed driving mode is released.