Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-10-06
2002-03-12
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S472000, C137S487500
Reexamination Certificate
active
06354276
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a method for adjusting an insertion amount of an adjusting pipe for a fuel injection valve.
2. Description of Related Art
A conventional method for adjusting an insertion amount of an adjusting pipe
15
will be described with reference to
FIGS. 1 and 3
.
A frequency, a pulse duration, a pulse amplitude of an electric current supplied into a coil
15
are fixed at predetermined amounts. An injection amount per valve stroke, of each sample fuel injection valve, in accordance with the predetermined electric current is different from each other. Since the frequency of the electric current is fixed, when the injection amount is defined, a flow amount per unit time in accordance with the electric current is also defined. In this prior art, the insertion amount of the adjusting pipe is adjusted by supplying the fixed electric current having a constant frequency, a constant pulse durability, and a constant pulse amplitude into the fuel injection valve
10
, and inserting the adjusting pipe
15
a housing
11
to change the injection amount until the flow amount reaches a target flow amount.
A back pressure valve
24
regulates the pressure of fluid flowing into the fuel injection valve
10
from a pump
20
. Next, a motor
30
rotates to insert the adjusting pipe
15
to a predetermined position where a spring
14
generates a spring force to urge a needle
12
to reach a valve seat
11
a.
A personal computer
40
receives a flow amount signal from a flow meter
23
and calculates the fluid flow amount per unit time. Since the insertion amount of the adjusting pipe
15
is small and the spring force of the spring
14
are small, the flow amount calculated by the personal computer
40
is larger than target flow amount.
An insertion amount is attained based on a relation map of the insertion amount and a difference between the calculated flow amount and the target flow amount. The relation map is previously memorized in a ROM of the personal computer
40
. The relation map differs in accordance with the specificity of each
20
fuel injection valve.
The personal computer
40
controls a driving circuit
41
to supply an electric current based on the attained insertion amount into the motor
30
. The motor
30
rotates to insert the adjusting pipe
15
into the housing
11
through an insertion screw
30
.
The adjusting pipe
15
is inserted into the housing
11
to increase a valve opening period and decrease a valve closing period of the fuel injection valve
10
, so that the injection amount is reduced, thereby reducing the fluid flow amount. Here, since a fluid flow becomes unstable due to the flow amount reduction, it is necessary to wait until the flow amount becomes stable to be constant to calculate a flow amount at this time based on a flow amount signal from the flow meter
23
. When the calculated flow amount becomes within standard range from the target flow amount, the insertion amount adjusting procedure is finished. If the calculated flow amount is out of the standard range, the above described adjusting cycle is repeated until the calculated flow amount becomes within standard range from the target flow amount.
However, according to the above described conventional adjusting procedure, since the flow amount is reduced due to the insertion of the adjusting pipe
15
, it is necessary to wait until the flow amount becomes stable to be constant to calculate a flow amount at the time when the insertion of the adjusting pipe
15
is completed, thereby increasing a total adjusting time.
Further, since the adjusting pipe
15
is press inserted into the housing
11
, the adjusting pipe
15
cannot return to the previous position thereof when the adjusting pipe
15
is excessively inserted into the housing
11
. Thus, the one cycle insertion amount based on the relation map is determined smaller than an insertion amount attaining the target flow amount, for preventing the adjusting pipe
15
from inserting excessively. Thus, it is difficult to adjust the insertion amount accurately with respect to an optimum insertion amount that can attain the target flow amount. As a result, even final flow amount attained by repeat of the insertion amount adjusting procedure must be larger than the target flow amount although it is within the standard range from the target flow amount, so that it is difficult to attain the target flow amount accurately.
SUMMARY OF THE INVENTION
An object of the present invention is to reduce a time for adjusting an insertion amount of an adjusting pipe, and to adjust the insertion amount accurately.
According to a first aspect of the present invention, an adjusting pipe is being inserted while changing an electric current for a coil to keep a flow amount of a fluid at a predetermined flow amount constantly. When the electric current supplied into the coil becomes a target electric current, the adjusting pipe is stopped being inserted, and the electric current is stopped being changed. That is, since the insertion amount of the adjusting pipe and the electric current are continuously adjusted and changed while keeping the flow amount constantly, there is no need to wait until the flow amount becomes stable as in the conventional adjusting method in which a fluid flow amount is decreased toward a target flow amount. Thus, the adjusting time is reduced.
Further, since the insertion amount of the adjusting pipe is adjusted while keeping the flow amount at the target flow amount, the insertion amount is accurately adjusted. Thus, the flow amount and an injection amount are highly accurately adjusted within the standard range from the target flow amount.
The adjusting method of the first aspect of the present invention is attained by merely changing a control program of a conventional adjusting system, so that there is no need to prepare an additional adjusting system.
According to a second aspect of the present invention, the electric current is changed by adjusting a frequency or a pulse duration thereof. An adjustment of the frequency or the pulse duration is easily done by a microprocessor or the like.
REFERENCES:
patent: 5048489 (1991-09-01), Fischer et al.
patent: 5575264 (1996-11-01), Barron
patent: 6016832 (2000-01-01), Vars et al.
patent: 6155233 (2000-12-01), Wade et al.
Inatsugi Nobutoshi
Mizukusa Koji
Toiyama Seigi
Yamaguchi Masahide
Denso Corporation
Moulis Thomas N.
Nixon & Vanderhye P.C.
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