Vehicle power transmission arrangements and electronic power controls

• US 4,107,776 A
• Filed: 02/24/1977
• Issued: 08/15/1978
• Est. Priority Date: 10/23/1975
• Status: Expired due to Term

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Beale, Julian R. A.
• Primary Examiner(s): Ruggiero, Joseph F.
• Application Number:
  US05/771,699
• Time in Patent Office: 537 Days
• Field of Search: 235/150.2, 235/150.21, 74/859, 74/866, 74/752 D, 74/861, 123/32 AE, 123/32 EA, 123/102, 364/424, 364/425, 364/431, 364/442
• US Class Current: 701/99
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• CPC Class Codes: B60W 10/109 of the toroïd type
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F16H 2015/383 with two or more sets of toroid gearings arranged in parallel
• CPC Class Codes: F16H 2059/743 using engine performance or power for control of gearing transmission input torque F16H2059/147
• CPC Class Codes: F16H 61/66259 using electrical or electronical sensing or control means
• CPC Class Codes: F16H 61/6648 controlling of shifting being influenced by a signal derived from the engine and the main coupling

Abstract

An electronically controlled transmission arrangement for an internal combustion engine driven vehicle such as a private automobile, permitting operation under normal conditions close to regions of minimum specific fuel consumption while also permitting bringing an engine in poor operating condition close to its maximum power speed. A transmission including a continuously variable gearing is controlled by an electronic microprocessor in response to signals representing driver-selected power-command, engine-speed, and drive shaft speed. The transmission is controlled so that the engine vehicle combination operates along an engine power-load line selected according to the power command. Transition circuitry prevents a sudden change in power-command from causing the transmission to alter its ratio so quickly that there is a transient change of delivered torque in the wrong direction.

Claims

1. A power arrangement for a wheeled vehicle having a drive shaft, said arrangement comprising an engine, continuously variable gearing between the engine and the drive shaft, power-command means operable by a vehicle driver to command a variation in engine power, and electronic control means for varying the torque transmitted by the continuously variable gearing,

said control means being responsive to the engine speed w_e, the drive shaft speed w_d and the extent of actuation R_a of the power command means such that the torque transmitted to the drive shaft is a different function of engine speed w_e for different values of R_a, said different functions corresponding to different power-load lines on an engine-power engine-speed graph, and

said control means including means, responsive to increased actuation R_a of the power-command means, for causing transition between a previous power-load line and a higher-engine-speed power-load line while maintaining transmitted power at least as high as the previous level of power, and responsive to reduced actuation R_a of the power-command means, for causing transition between a previous power-load line and a lower-engine-speed power-load line while maintaining transmitted power at least as low as the previous level.

2. A power arrangement for a wheeled vehicle having a drive shaft, said arrangement comprising an engine, transmission means for coupling the engine to the drive shaft, said transmission means including continuously variable gearing, power-command means operable by a vehicle drive for demanding a variation in engine power, sensor means for providing signals indicative of the entrance speed w_e, the drive shaft speed w_d and the extent of actuation R_a of the power command means, actuator means for regulating the torque transmitted by said gearing, and

electronic control means for receiving from said sensor means inputs indicative of w_e, w_d and R_a and for providing control signals to said actuator means responsive to said inputs for determining the torque transmitted to the drive shaft in accordance with the power produced by the engine as a function of the engine speed w_e and one of a plurality of power-load lines for the engine, said load lines corresponding to respective extents of actuation R_a of the power-command means such that for increasing values of R_a the load line selected occurs at higher engine speeds w_e ;

said control means including means for causing transition responsive to increased actuation R_a between the previously selected power-load line and a higher engine speed power-load line while maintaining transmitted power at least as high as the previous level of power, and in response to reduced actuation R_a causing transition between the previous power-load line and a lower engine speed power-load line while maintaining transmitted power at least as low as the previous level.

3. An arrangement as claimed in claim 2 wherein said control means establishes load lines, corresponding to values of R_a and w_d greater than given values, which increase more steeply with engine speed than does a straight line on the engine-speed engine-power graph joining a region of maximum engine power to a region of lowest specific fuel consumption.

4. An arrangement as claimed in claim 3 wherein, in response to maximum actuation R_a of the power-command means and values of w_d greater than a second given value, a load-line is selected which increases at least twice as steeply with engine-speed as does a straight line on the engine-speed engine-power graph joining said region of maximum engine power to said region of lowest specific fuel consumption.

5. An arrangement as claimed in claim 2, wherein the slopes of the lines on the engine-power engine-speed graph increase for increasing respective values of R_a.

6. An arrangement as claimed in claim 2, wherein said means for causing transition, responsive to actuation of the power-command means to demand increased acceleration, so controls the continuously variable gearing that the torque transmitted to the drive shaft increases unless the acceleration of the engine is less than a predetermined value.

7. An arrangement as claimed in claim 6, wherein said means for causing transition includes means for comparing the present value R_a of the power command means with a value R'"'"'_a related to a previous value of R_a, and repeatedly modifying said value R'"'"'_a so as to converge toward the present value of R_a.

8. An arrangement as claimed in claim 2, wherein said actuator means comprises a hydraulic pump, a solenoid operated pressure control valve and means for opposing torque reaction force on the continuously variable gearing responsive to hydraulic pressure determined by said valve, said pressure increasing a perpendicular component of force on the effective areas of contact between elements of said continuously variable gearing which provide the continuous variation of speed ratio.

9. An arrangement as claimed in claim 8, in which said hydraulic pressure is reduced if the magnitude of the rate of change of the engine speed/drive shaft speed ratio exceeds a predetermined value.

10. An arrangement as claimed in claim 9, in which a reference value of said speed ratio is derived if the magnitude of the rate of change of said speed ratio exceeds a second predetermined value, the reference value being repeatedly modified so as to converge towards the present value of said speed ratio, and the hydraulic pressure is maintained low until any difference between said reference value and said present value is less than a predetermined value.

11. An arrangement as claimed in claim 8, wherein control signals from said electronic control means so regulate the gearing ratio of the continuously variable gearing as to reduce differences between actual engine speed w_e and a target engine speed associated with the extent of actuation R_a of the power-command means, a target operating line selected for the engine to minimize low fuel consumption, and the limitations of gear ratio of the continuously variable gearing.

12. An arrangement as claimed in claim 11 in which said transmission means is operable in at least first and second modes, the first mode being adapted for reverse and low forward speed and the second for medium and high forward speeds, wherein said control means includes means responsive to said transmission being in the first mode for establishing a target engine speed greater than the target engine speed when the transmission is in the second mode.

13. An arrangement as claimed in claim 11, in which the torque T_d transmitted to the drive shaft is related to the actual engine speed w_e and the target engine speed w_et by an equation of the form:

space="preserve" listing-type="equation">T.sub.d = T.sub.c + Y (w.sub.e - w.sub.et)

where

Y is a factor which determines the rate of increase of T_d with w_e, and

T_c is a function of R_a and represents the torque commanded on the drive shaft by the driver'"'"'s operation of the power command means.

14. An arrangement as claimed in claim 13, in which the output R_t from said electronic control means for regulating the torque produced by the engine is related to the actual engine speed w_e and the target engine speed w_et by an equation of the form:

space="preserve" listing-type="equation">R.sub.t = Y.sub.1 T.sub.c w.sub.d + Y.sub.2 (w.sub.et - w.sub.e) + Y.sub.3 w.sub.et + Y.sub.4

where

Y₁, y₂, y₃ and Y₄ are constants, of which at least Y₁ and Y₄ may have different values for different ranges of T_c.w_d, w_d is the drive shaft speed, and

T_c is a function of R_a and represents the torque commanded on the drive shaft by the driver'"'"'s operation of the power command means.

15. An arrangement as claimed in claim 2 wherein said electronic control means includes means for providing an engine torque control signal, and said arrangement comprises a second actuator means associated with the engine for regulating the torque produced by the engine responsive to said engine torque control signal.

16. An arrangement as claimed in claim 15 wherein said engine torque control signal is varied to a value correspondinh to lower engine torque as the road speed falls below a predetermined value.

17. An arrangement as claimed in claim 15 in which said control means includes means for comparing actual engine-speed with a target engine-speed determined in accordance with the extent of actuation R_a, a target operating line for the engine for low fuel consumption and limitations of the gear ratio of the continuously variable gearing;

and means for varying said engine torque control signal responsive to said comparison.

18. An arrangement as claimed in claim 2, additionally comprising a gearing-select means operable by a vehicle driver, and said electronic control means further includes means for regulating the continuously variable gearing so as to provide engine-braking responsive both to the extent of actuation R_a of the power-command means and the gearing-select means.

19. An arrangement as claimed in claim 18 , in which for small values of R_a the extent of engine braking obtained is varied by changing the rear ratio in the continuously variable gearing while maintaining substantially zero actuation of the actuator means for determining engine torque.