Starter system for automatically turning off and restarting a motor vehicle engine

• US 4,959,962 A
• Filed: 02/07/1990
• Issued: 10/02/1990
• Est. Priority Date: 08/27/1987
• Status: Expired due to Fees

• Current Assignee: Man Nutzfahreuge GmbH
• Original Assignee: Man Nutzfahreuge GmbH
• Inventors: Hagin, Faust, Drewitz, Hans
• Primary Examiner(s): Ostrager, Allen M.
• Application Number:
  US07/476,143
• Time in Patent Office: 237 Days
• Field of Search: 60/625, 60/626, 60/627, 74/687
• US Class Current: 60/626
• CPC Class Codes: B60K 2006/126 the hydraulic accumulator starts the engine
• CPC Class Codes: F02N 11/0825 related to prevention of engine restart failure, e.g. disabling automatic stop at low battery state
• CPC Class Codes: F02N 2200/0815 Vehicle door sensors
• CPC Class Codes: F02N 2200/102 Brake pedal position
• CPC Class Codes: F02N 7/08 the engines being of rotary type
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

In order to avoid the necessity of a conventional electric starter motor a hydrostatic starting system for the engine of a motor vehicle is proposed for the engine whose output shaft is connected with a hydromechanical power transmission, composed of a mechanical part and at least two hydrostatic machines. The starter system comprises its own hydraulic accumulator which as regards its filling capacity and power output is designed for starting the engine at least once and a controller which responds to certain halt and operational states of the vehicle. The charging of the hydraulic accumulator takes place during braking of the vehicle via the hydrostatic machines of the power transmission or, if there is insufficient brake power, of an auxiliary device.

Claims

1. The combination comprising a hydromechanical power transmission connected to the output shaft of an engine of a motor vehicle for delivering power from the engine to drive the vehicle, and a starter system connected to said transmission to start the engine, said transmission including a mechanical drive part connected to the output shaft of the engine and a hydraulic part including two hydrostatic machines drivingly connected to one another and to said mechanical drive part, said starter system comprising a hydraulic starter accumulator connected to said two hydrostatic machines for being supplied with pressure fluid from said hydrostatic machines during drive of the engine, and for delivering the pressure fluid back to said hydraulic part of the transmission when the engine is halted to start the engine, said hydraulic starter accumulator having a filling capacity to provide a power output to start the engine at least once, means for preventing motion of the vehicle at least in the reverse direction during starting of the engine, controller means connected to said hydraulic starter accumulator, said engine and said hydromechanical power transmission for acting during halted and operational states of the vehicle for

(a) turning off the engine,

(b) starting the engine by supplying the pressure fluid in the hydraulic starter accumulator to said hydraulic part to drive the output shaft via said transmission, and

(c) supplying the starter accumulator with pressure fluid from the transmission during braking of the vehicle, and

auxiliary means connected to said starter accumulator for pressurizing the starter accumulator to enable starting the engine in the event that the accumulator is insufficiently pressurized by the transmission during braking of the vehicle.

2. The combination as claimed in claim 1 wherein said controller means is connected to said means which prevents motion of the vehicle at least in the reverse direction for operating said means during operation (b).

3. The combination as claimed in claim 1 wherein said vehicle further comprises a brake energy recovery means including a high pressure accumulator, a low pressure accumulator, a hydraulic control device, shut off valves for said high and low pressure accumulators and connecting lines connecting said high and low pressure accumulators to the hydrostatic machines via said hydraulic control device, said hydraulic control device and shut-off valves effecting charging and discharging of the hydraulic accumulators through the power transmission, said starter accumulator being charged under the control of the controller means during braking of the vehicle via the power transmission in preference to the charging of the high pressure accumulator of the brake energy recovery means.

4. The combination as claimed in claim 3 wherein the starter accumulator is connected via a first hydraulic line with the hydraulic control device and a solenoid valve is provided in said first hydraulic 1 line for being operated by the controller means for controlling connection of the starter accumulator with said hydraulic control device.

5. The starter system as claimed in claim 4 comprising a bypass line including a check valve therein bypassing said shut off valve, said check valve being opened only in the charging direction of flow.

6. The starter system as claimed in claim 3 comprising means for returning excess oil flowing from the first accumulator during starting including a drain line connected to the hydraulic control device and to the tank and a shut off valve in said drain line operated by said controlling means.

7. The combination as claimed in claim 3 comprising a pressure sensor responsive to the pressure in the starter accumulator for sending a signal via a signal line to the controller means, said controller means being constructed only to produce a signal causing charging of the starter accumulator when said pressure sensor indicates that the degree of charging of said starter accumulator is below a minimum value, said auxillary means comprising an electric motor, and an auxiliary pump connected to said motor for being driven thereby, said controller means being connected to said motor to drive the same when the brake energy produced during braking of the vehicle is not sufficient for charging the starter accumulator and the degree of charge in said starter accumulator is not sufficient for starting the engine.

8. The combination as claimed in claim 7 comprising an oil tank connected to said auxiliary pump, a connecting line connecting the auxiliary pump to said starter accumulator and a check valve in said connecting line which opens only in the direction of flow from the auxiliary pump to the starter accumulator.

9. The starter system as claimed in claim 1 wherein said controlling means only turns off the engine when it receives a signal indicating that there is sufficient pressure in the first accumulator for starting the engine at least once.

10. The starter system as claimed in claim 1 comprising means for returning any excess hydraulic oil during starting of the engine from the first accumulator to drive the first hydrostatic machine including a drain line connected to the hydraulic control device, a hydraulic oil tank connected to the hydraulic control device and a shut off valve in said drain line operated by said controller means.

11. The combination as claimed in claim 1 wherein said controller means automatically turns the engine off in response to at least one signal indicating that the vehicle is in a halted condition indicated by at least one of the following:

application of a parking brake;

a stationary state of driving wheels of the vehicle;

an open state of at least one door of the vehicle; and

operation of the brakes after the wheels have ceased moving.

12. The combination as claimed in claim 11 wherein said controlling means includes means for restarting the engine after a previous halting thereof automatically when at least one of the signals for turning off the engine is discontinued.

13. The combination as claimed in claim 11 wherein said controlling means includes means for starting and restarting the engine automatically when a signal indicating actuation of an accelerator pedal of the vehicle is produced.

14. The combination as claimed in claim 12 wherein said controller means includes means for starting and restarting the engine automatically when a signal indicating actuation of an accelerator pedal of the vehicle is produced and a shut off valve is opened, under the power supplied by expansion of the fluid in the starter accumulator which drives one of the hydrostatic machines through the mechanical part of the power transmission while the other hydrostatic machine is stationary.

15. The starter system as claime din claim 14 wherein the starter of the engine is only operated by the controller means when the shut off valve is open and the controller means receives a signal indicating that the engine speed corresponds to a successful ignition, even if a swash plate angle of the hydrostatic machine is decreased to zero, said shut off valve then being closed when said speed is reached.

16. The combination as claimed in claim 1 comprising a pressure sensor responsive to the pressure in the starter accumulator for sending a signal via a signal line to the controller means.

17. The combination as claimed in claim 16 wherein said controller means is constructed only to produce a signal causing charging of said starter accumulator when said pressure sensor indicates that the degree of charging of said starter accumulator is below a minimum value.