WO1997003305A1

WO1997003305A1 - Braking method

Info

Publication number: WO1997003305A1
Application number: PCT/SE1996/000863
Authority: WO
Inventors: Kjell Hansson
Original assignee: Im Transmission Ab
Priority date: 1995-07-07
Filing date: 1996-06-28
Publication date: 1997-01-30
Also published as: SE9502500L; SE506646C2; AU6373396A; SE9502500D0

Abstract

A method relating to the braking of a vehicle uses the kinetic energy of the vehicle to perform work specific to the vehicle in conjunction with initial application of the vehicle brakes.

Description

BREAKING METHOD

The present invention relates to a method of utilizing the kinetic energy of a vehicle in conjunction with braking the vehicle.

It is known to preserve and store the kinetic energy of a vehicle in conjunction with braking or reducing h s ped of said vehicle and then to use this stored energy to set the vehicle in motion. This storage of kinetic energy and its conversion into work has hitherto involved the use of compli¬ cated devices and arrangements, such generator-battery motors, pressure accumulators, rotating flywheels, and so on. Electri¬ cal and hydrodynamic vortex brakes have been developed parallel with these known devices or arrangements with the intention of reducing brake wear.

The work carried out by various different types of vehicle is power requiring. Examples of such vehicles are garbage collection trucks fitted with garbage compactors, cement mixing trucks, fork-lift trucks and refrigeration trucks. The engine power of such vehicles must be adapted to suit the purpose of the vehicle concerned. One example in this regard is a garbage collection truck, which can make as many as 600 starts and stops in a days work. The compactor is normally activated at the same time as the vehicle engine is started-up, therewith reducing the available vehicle start-up power while reaching high fuel consumption and high exhaust emission values at the same time.

In accordance with the present invention as defined in the characterizing clauses of respective claims, the kinetic energy of the vehicle is utilized during the initial part of a vehicle braking sequence in the performance of work that is specific to the vehicle concerned, for instance to activate the compactor of a garbage collection truck in conjunction with braking the vehicle and therewith compact, or compress, the garbage contained in the vehicle.

The method can be readily carried out and does not require the use of expensive and complicated devices for storing the energy that is later to be used.

The invention will now be described in more detail with reference to the accompanying drawing, the single figure of which illustrates schematically the concept of the inventive method.

Shown in drawing is an on/off switch 1 which functions to energize and de-energize a magnetic valve 2 that controls activation of a disk power take-out 3 in the form of a multiple-disk clutch. The clutch 3 has an input shaft 7 which is connected to a vehicle-mounted power take-out, and an output shaft which is connected to a power unit, eg in the form of an hydraulic pump 4, and is activated by hydraulic pressure from the gear box, or by compressed air. The input shaft 7 connected to the disk power take-out may be in constant gear engagement with the vehicle drive shaft for instance. The kinetic energy of the vehicle may also be taken out from the output shaft of the gear box or from its input shaft (manual gear box). In the case of automatic gear boxes kinetic energy may be taken out at the turbine shaft of the gear box or from the torque conversion pump. The power take-out means may also be placed between engine and gear box, or the engine crank shaft may drive the disk power take-out through the medium of gear means.

As the hydraulic pump 4 is driven, the braking power is regulated by adjusting the pressure in the hydraulic system 8 to the desired level through the medium of control means 6 and pressure reduction valves, in the illustrated case three such valves, which have mutually different reduction pressures. As shown in the drawing, the three pressure reducing valves, which have mutually different reduction pressures, are connected in series. Naturally, a single pressure reducing valve that has different reduction pressures may be used or the number of valves used may differ from the number shown. In order to utilize the kinetic energy of the vehicle effectively and to reduce wear on the vehicle brakes, the device or arrangement is activated, ie the disk power take-out is activated, with the aid of a magnetic valve or solenoid valve. This may be achieved through the medium of the brake light contacts as pressure is applied to the brake pedal and before the vehicle brakes are fully applied. The pressure reducing valve in the hydraulic system may be controlled in response to pressure on the brake-pedal - the control means 6 - or by the brake pressure in the hydraulic brake system, so that increas¬ ing pedal pressure will successively increase the pressure in the hydraulic system, which in turn successively increases the braking effect.

The invention is thus suited for vehicles that stop and start repeatedly, wherein the invention can be applied to town or city run concrete mixing vehicles for rotation of the mixer in the initial braking stage. Similarly, the invention can be applied in fork lift trucks to raise or lower the forks, or tines, in response to initial pressure on the brake. The invention can also be applied in refrigeration transport trucks, such as to operate the compressor when the truck is braked or slowed down in same other way or is held at a constant speed, for instance when driving downhill.

The invention affords significant advantages when applied to vehicles of the aforesaid kind because engine power is not used to drive the additional equipment, which in many cases enables engines of lower power capacities to be used and thereby also use less fuel than would otherwise be the case and reduce exhaust emissions. Wear on the brakes will also be less than would otherwise be the case and cooling requirements in respect of hydromechanical brakes are also reduced. The braking power can be controlled when the device or arrangement is in operation and is able to drive a power unit in the form of an hydraulic pump or a compressor for example in the case of a refrigeration transport truck.

Claims

1. A method relating to the braking of vehicles, characterized by using the kinetic energy of the vehicle to perform work specific to the purpose of the vehicle during initial braking of the vehicle.

2. A method according to Claim 1 , characterized by transfer¬ ring kinetic energy to a power unit (4) through the medium of a disk power take-out (3), said power take-out being operated by compressed air or by hydraulic pressure from the vehicle gear box.

3. A method according to Claim 1 or 2, characterized by using the pressure in the hydraulic brake system of the vehicle to control one or more pressure reduction valves (5) to adjust the pressure in the hydraulic circuit (8) of the power unit (4).

4. A method according to Claim 1 or 2, characterized by using the vehicle brake pedal to control one or more pressure reduction valves (5) so as to adjust the pressure in the hydraulic circuit (8) of the power unit (4).

5. A method according to any one of the preceding Claims, characterized by causing the disk power take-out (3) to be activated immediately braking of the vehicle is begun.

6. A method according to Claim 5, characterized by activating the disk power take-out (3) through the medium of a magnetic valve (2), said valve being activated in conjunction with applying the brakes of the vehicle.

7. A method according to any one of the preceding Claims, characterized by transferring kinetic energy from a vehicle- carried power take-out through the medium of a constantly engaged gear wheel.

8. A method according to any one of the preceding Claims, characterized by using a power unit in the form of an hydraulic pump (4) .