Method of automatically controlling modulation pressure in an automatic transmission including addressing a stored engine data matrix with a combined address formed from both digitized engine speed and load

• US 5,126,940 A
• Filed: 08/07/1990
• Issued: 06/30/1992
• Est. Priority Date: 03/03/1988
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Haubner, Georg
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US07/563,924
• Time in Patent Office: 693 Days
• Field of Search: 364/424.1, 364/431.04, 364/431.05, 364/431.12, 74/866, 74/867
• US Class Current: 701/54
• CPC Class Codes: F16H 2061/0096 using a parameter map
• CPC Class Codes: F16H 59/14 Inputs being a function of torque or torque demand
• CPC Class Codes: F16H 61/0437 by using electrical signals F16H61/0403 and F16H61/061 take precedence

Abstract

The method of controlling the modulation pressure in an automatic transmission of a motor vehicle engine includes determining which of n types of engines is being controlled, converting a digitized measured engine load value to one of eight scaled binary values, converting a digitized measured engine speed value signal to one of 32 scaled binary values, combining the scaled binary values of both engine speed and load into an address word for addressing one of n×256 storage locations of a data storage device containing reference control data, addressing the storage location corresponding to the address word and transferring the contents of the storage location so addressed to a microprocessor, which generates a current controlling a modulation pressure valve connected to the transmission according to the predetermined engine speed and load dependent data. For greater control sensitivity, reference data is retrieved from adjacent storage locations and an interpolation of the reference data in those locations is performed.

Claims

1. A method of controlling a modulation pressure in an automatic transmission of a motor vehicle engine having means for converting engine load and engine speed into an engine load digital signal and an engine speed digital signal, a microprocessor connected to said means for converting so as to receive said engine load digital signal and said engine speed digital signal, reference data storage means having a plurality of storage locations, said reference data storage means containing stored predetermined engine speed and load dependent reference data in said storage locations and being connected with said microprocessor so as to be able to supply said microprocessor with said reference data from each of said storage locations and a modulation pressure regulating valve controllable by an electric current determined by said microprocessor, said method comprising the steps of combining said engine load digital signal and said engine speed digital signal in an address word for addressing one of said storage locations of said reference data storage means, addressing said storage location corresponding to said address word and transferring the contents of said storage location to said microprocessor so that said microprocessor contains said predetermined engine speed and load dependent data, and determining said current controlling said modulation pressure valve according to said predetermined engine speed and load dependent data in said microprocessor.

2. A method as defined in claim 1, wherein each of the address words consists of eight bits including a higher three bits and a lower five bits, the three higher bits being determined by the engine load digital signal and the lower five bits being determined by the engine speed digital signal.

3. A method as defined in claim 2, wherein the engine load digital signal is transferred into an 8 bit accumulator of the microprocessor and then shifted left until the lower five bits are cleared so that the load digital signal is located in the upper three bits in the accumulator to partially form the address word in the accumulator.

4. A method as defined in claim 3, wherein the engine speed digital signal is recalculated to assume a binary value equivalent to one of a predetermined 9 to 31_d speed ranges, and transferring the binary value of said one speed range into the lower five bits in the accumulator of the microprocessor to complete formation of the address word.

5. A method as defined in claim 4, further comprising converting said engine speed to said engine speed digital signal by providing a spur gear having teeth, said spur gear being nonrotatably attached to a drive shaft of the engine of the motor vehicle, and a sensor located adjacent said spur gear so as to be able to count the number of teeth moving by said sensor in a predetermined time interval, said sensor producing an output pulse when one of the teeth passes said sensor, by counting the output pulses from the sensor during the time interval to obtain a counted number of pulses and converting the counted number into a corresponding digital value, by storing the digital value in tan engine speed register of the microprocessor;

and by recalculating the digital value in the engine speed register by adding thereto a fixed digital value.

6. A method as defined in claim 5 wherein the predetermined engine speed and load dependent reference data stored in the data storage means correspond to pulse-interval ratios of said current controlling said modulation pressure valve and are read out from the data storage means into the microprocessor during the time interval of the counting.

7. A method as defined in claim 5 further comprising the step of testing whether the value stored in the engine speed register falls below a predetermined minimum or exceeds a predetermined maximum value.

8. A method as defined in claim 5 wherein prior to the addition of the fixed digital value a complement of the value stored in the engine speed register is calculated.

9. A method as defined in claim 4, wherein the predetermined 0 to 31_d engine speed ranges cover, when combined, an actual speed range between 400 to 2,707 rotations per minute.

10. A method as defined in claim 1 wherein said data storage means contains only 256 of said storage locations for said predetermined engine speed and load dependent reference data, and further comprising computing intermediate values of said engine speed and load dependent reference data by interpolation between two reference data retrieved from adjoining storage locations in said data storage means and determining said current also according to said intermediate values.

11. A method as defined in claim 10 wherein said interpolation is a 16-fold interpolation.

12. A method as defined in claim 1 wherein said data storage means contains n×

256 of said storage locations for said predetermined engine speed and load dependent reference data for n different types of said motor vehicle engines and said data storage means contains 256 of said predetermined engine speed and load dependent reference data for each of said n different types of said engines, and said method further comprises selecting one of said 256 of said reference data according to which of said n types of said engine is being controlled.

13. A method of controlling a modulation pressure in an automatic transmission of a motor vehicle engine having means for converting engine load and engine speed into an engine load digital signal and an engine speed digital signal, a microprocessor connected to said means for converting so as to receive said engine load digital signal and said engine speed digital signal, reference data storage means having only 256 storage locations, said reference data storage means containing stored predetermined engine speed and load dependent reference data in said storage locations and being connected with said microprocessor so as to be able to supply said microprocessor with said reference data and a modulation pressure regulating valve controllable by an electric current determined by said microprocessor, said method comprising the steps of converting said engine load digital signal to one of eight scaled binary values, converting said engine speed digital signal to one of 32 binary values, combining said scaled binary values of said engine load digital signal and said engine speed digital signal into an address word for addressing one of said 256 storage locations of said reference data storage means, addressing said storage location corresponding to said address word and transferring the contents of said storage location to said microprocessor so that said microprocessor contains said predetermined engine speed and load dependent data stored at said storage location, and determining said current controlling said modulation pressure valve according to said predetermined engine speed and load dependent data in said microprocessor.

14. A method of controlling a modulation pressure in an automatic transmission of a motor vehicle engine having means for converting engine load and engine speed into an engine load digital signal and an engine speed digital signal, a microprocessor connected to said means for converting so as to receive said engine load digital signal and said engine speed digital signal, reference data storage means having only n×

256 storage locations for n types of said motor vehicle engines, said reference data storage means containing stored predetermined engine speed and load dependent reference data for each of said engine types in said n×

256 storage locations and being connected with said microprocessor so as to be able to supply said microprocessor with said reference data and a modulation pressure regulating valve controllable by an electric current determined by said microprocessor, said method comprising the steps of determining which of said n types of said motor vehicle engines is being controlled, converting said engine load digital signal to one of eight scaled binary values, converting said engine speed digital signal to one of 32 scaled binary values, combining said scaled binary values of said engine load digital signal and said engine speed digital signal into an address word for addressing one of said 256 storage locations for said n type of said engine being controlled, addressing said storage location corresponding to said address word and transferring the contents of said storage location to said microprocessor so that said microprocessor contains said predetermined engine speed and load dependent data stored at said storage location, and determining said current controlling said modulation pressure valve according to said predetermined engine speed and load dependent data in said microprocessor.