WO1987002740A1

WO1987002740A1 - Fuel injection system

Info

Publication number: WO1987002740A1
Application number: PCT/DE1986/000248
Authority: WO
Inventors: Bernhard Vogt
Original assignee: Robert Bosch Gmbh
Priority date: 1985-10-30
Filing date: 1986-06-13
Publication date: 1987-05-07
Also published as: EP0244419A1; JPS63501234A; KR880700157A; DE3538520A1

Abstract

The above system measures the throttle valve angle and the rotation speed and transmits them to an electronic motor control which, during warming-up of the engine calculates on the basis of the starting temperature of the engine and throttle valve angle a heating factor designed to correct the quantity to be injected when the engine has warmed up. A heating reduction factor FWLA, depening on the engine starting temperature and the angle of the throttle valve, influences the heating factor FWL according to the equation FWL=(FWL, alpha>alpha2-1) FWLA+1, where FWL is the effective heating factor, FWL, alpha>alpha2 is the heating factor when loaded and FWLA is the heating reduction factor. This prevents additional and unwanted enrichment during the warming-up phase.

Description

Fuel injection system

State of the art

The invention is based on a fuel injection system according to the type of the main claim.

In the event of a cold start of a motor vehicle with subsequent warm-up, the fuel-air mixture should be in a narrow range for idling and under load, both for idling and under load. This can only be achieved if, in addition to the amount of fuel injected, the air mass drawn in through the nozzle is known as precisely as possible.

The conventional warm-up correction does not take into account the fact that different temperature differences between the throttle valve and the surrounding connector housing occur during warm-up. These temperature differences are responsible for the fact that the nozzle housing expands or contracts more than the throttle valve and therefore the opening cross section between the nozzle housing and throttle valve can be up to 15% smaller, especially in idle mode. This temperature-dependent change in cross-section, which is dependent on the starting temperature, causes the fuel-air mixture to become rich during warm-up and has a stronger effect when idling than under load.

Advantages of the invention

The injection system according to the invention with the features of the main claim has the advantage that a warm-up weakening factor dependent on the starting temperature of the engine and the throttle valve angle corrects the warm-up factor in such a way that the temperature differences and the associated different expansion of the throttle valve and connector housing are taken into account. This correction prevents unwanted additional enrichment of the fuel-air mixture during warm-up in idle and near idle. In the preferred embodiment, the

Start calculated warm-up attenuation factor is a value less than or equal to 1, which multiplied by the load warm-up factor at the end of warm-up results in 1, so that when the operating temperature is reached, the normal injection quantity or injection time is guaranteed, which can be found in the engine-specific characteristic curve. This characteristic curve is stored in the engine control computer. The values of the water temperature transmitted to the engine control are used to determine the engine temperature.

Advantageous developments and improvements of the injection system specified in the main claim are possible through the measures listed in the further subclaims.

drawing

Embodiments of the invention are shown in the drawing and in the description below explained in more detail. Show it:

Figure. 1 shows a course of the warm-up weakening factor F _WLA as a function of the cooling water temperature of the engine when starting,

FIG. 2 shows a course of the warm-up weakening WLA at a cooling water temperature of the engine at the start of -30 ° C. as a function of the throttle valve angle,

FIG. 3 shows a course of the warm-up weakening WLA at a cooling water temperature of the engine at the start of 0 ° C. as a function of the throttle valve angle,

Figure 4 shows a course of the warm-up factor F _WL at a cooling water temperature of the engine at the start of -30 ° C as a function of the current cooling water temperature at different throttle valve angles and

FIG. 5 shows a course of the warm-up factor F _WL at a cooling water temperature of the engine at the start of 0 ° C. as a function of the current cooling water temperature at different throttle valve angles.

The course of the warm-up attenuation factor F _WLA shown in FIG. 1 depends on the cooling water temperature T _W , Start. of the engine when starting. The warm-up attenuation factor F _WLA has the value F ₁ = 0.5 at -30 ° C, the value F ₂ = 0.75 at 0 ° C and the value F ₃ = 1.0 at 60 ° C. The intermediate values of the warm-up factor F _WLA are calculated by linear interpolation. At a cooling water temperature T _W , start, greater than 60 ° C, the warm-up attenuation factor F _{WL A} = 1.0, ie there are none from a start temperature of 60 ° C Warm-up reduction more, since from this temperature the load warm-up factor F _{WL, a> a2} applies to all throttle valve angles.

FIG. 2 shows a possible course of the warm-up heat recovery WLA at a cooling water temperature T _{W, starting} at -30 ° C. as a function of the throttle valve angle α. The warm-up reduction WLA has the value F ₁ = 0.5 up to a throttle valve angle α ₁ = 5 °. If the throttle valve angle α is increased to approximately 12 °, the value of the warm-up weakening WLA increases to 1.0, ie there is no longer any warm-up weakening, since the load warming factor F _{WL, α> α2} is then used. The values of the warm-up weakening WLA lying between the throttle valve angles α _{1 and} α ₂ are calculated by means of linear interpolation.

The example given in Figure 3 the course of the warm-attenuation WLA applies to a cooling water temperature TW _start of the engine at the start of 0 ° C. in the

In contrast to FIG. 2, the value F ₂ = 0.75 results for the warm-up weakening WLA up to a throttle valve angle et. The warm-up attenuation values WLA for throttle valve angles between α ₁ and α ₂ are calculated by linear interpolation.

FIG. 4 shows the course of the warm-up factor F _WL at a cooling water temperature of the engine at the start T _{W, start} = -30 ° C. as a function of the current one

Cooling water temperature T _W represents. The warm-up _attenuation factor F _WLA then assumes the value F ₁ = 0.5 according to FIG. The characteristic curve a shows the warm-up _factor at idle F _{WL, α≤ α1 of} the ZB the values 1.5 at -30 ° C, 1.25 at 0 ° C, 1.10 at 30 ° C, 1.04 at 60 ° C and 1, 00 at 90 ° C assumes. The characteristic curve b, on the other hand, shows the warm-up factor at load F _{W, α> α2,} the values of which, for example, 2.00 at -30 ° C,

1.50 at 0 ° C, 1.20 at 30 ° C, 1.08 at 60 ° C and 1.00 at 90 ° C. The hatched value range 1 indicates the values for the warm-up factor F _WL as a function of the throttle valve angle α, which can be, for example, between α ₁ = 5 ° and α ₂ = 15 °. The two characteristic curves a, b and a value range 1 delimited between them are according to the equation

F _WL = (F _{WL, α> α 2} - 1). F _WLA +1

certainly. With a throttle valve angle α> α2 there is no longer any warm-up reduction, ie the load warm-up factor F _{WL α> α2} applies

In the course of the warm-up factor F _WL shown in FIG

Water temperature T _{W, start} = 0 ° C assumed. The resulting values are shown in the diagram, the warm-up attenuation factor F _{WL A} according to FIG. 1 assuming the value F ₂ = 0.75.

Claims

1. A fuel injection system in which the throttle valve angle and the speed are measured and fed to an electronic engine control system which, during warm-up, calculates an accumulation of warm-up depending on the starting temperature of the engine and the throttle valve angle to correct the injection quantity required when the engine is warm, characterized in that that a warm-up attenuation factor F _{WL A} which is dependent on the starting temperature of the engine and which is calculated at the start and has a value less than or equal to 1 has the warm-up factor F _WL according to the equation, depending on the throttle valve angle α

F _WL = (F _{WL, α> α2} -1). F _WLA +1

influenced, where F _{WL is} the actual warm-up factor and

F _{WL, α> α2} is the warm-up factor under load.

2. Injection system according to claim 1, characterized in that the warm-up attenuation factor F _WLA assumes a higher value at a higher starting temperature and a smaller value at a lower starting temperature and the value at a starting temperature of greater than or equal to 60 ° C 1 b.

3. Injection system according to claim 2, characterized in that the warm-up reduction factor F _{WLA is} 0.5 at a starting temperature of -30 ° C, 0.75 at 0 ° C and 1.0 at over 60 ° C and values in between by linear interpolation be determined mathematically.

4. Injection system according to one of the preceding claims, characterized in that the warm-up absorption factor F _{WLA is} constant at a small throttle valve angle, which is for example between 0 ° and 5 °, at the same starting temperature but any instantaneous temperature of the cooling water.

5. Injection system according to one of the preceding claims, characterized in that the warm-up _attenuation factor F _WLA calculated at the start increases linearly from its original value to the value 1 as a function of the throttle valve angle in the angular range between approximately 5 ° and 15 °.

6. Injection system according to one of the preceding claims, characterized in that the warm-up factor F _{WL, α> α2} approximately 2.0 at -30 ° C, 1.5 at 0 ° C, 1.20 at 30 ° C, 1.08 at 60 ° C and 1.0 at 90 ° C, and the values in between are determined by linear interpolation.