JPS6313454Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel flow rate detection device installed in a fuel injection device of a diesel engine.

In the case of a fuel injection device, for example, a bottle-type distribution type injection pump, as shown in FIG. A constant reciprocating motion is performed by the contacting roller 4, and the operation of the cam disk 2 is transmitted to the plunger 5, so that the plunger 5 simultaneously performs rotation for distribution and reciprocating motion for sucking and pumping fuel. ing.

By the way, in the above-mentioned pump, in order to detect the load for exhaust gas control etc., that is, the fuel flow rate, conventionally a pick-up is provided on the control sleeve 6 that is inserted into the plunger 5 and which adjusts the fuel flow rate, and the control is controlled by this pick-up. The movement of the sleeve, that is, the effective stroke of the plunger 5 was detected, and the fuel flow rate was determined from this. However, when the pick-up is attached to a moving object such as the control sleeve 6, the following problems occur. That is, the attachment relationship between the control sleeve 6 and the pickup actuator and the attachment relationship between this actuator and the pickup detection coil are very difficult, and there is a problem in that durability against vibrations cannot be ensured. In other words, it was unreliable and expensive.

Therefore, a circuit is provided to calculate the actual fuel injection amount from the peak value of the fuel pressure discharged from the plunger, and the fuel injection amount is calculated from the actual injection amount output from this circuit and the target injection amount determined based on the engine operating condition. There is an invention disclosed in Japanese Unexamined Patent Publication No. 57-32021 in which the amount is adjusted.

As pointed out in this publication, there is a predetermined relationship between the fuel injection time T and the fuel injection amount, but the peak value of the fuel injection pressure and the injection time T are dependent on temperature, changes over time, and waveforms. It is not necessarily constant due to the influence of Therefore, when calculating the actual fuel injection amount from the peak value of fuel pressure as in this prior art, it is difficult to ensure accuracy, and furthermore, a measuring device equipped with an arithmetic circuit for estimating the injection time is required. There was a need for further improvement.

As a result of intensive research to solve the above problem, the present inventor has developed a pressure sensor that operates when the fuel pressure during the fuel injection stroke of the plunger exceeds a predetermined value, for example, between the plunger and the delivery valve. The operating time of the pressure sensor is
That is, the inventors have discovered that by measuring the fuel injection time of the pump, it is possible to detect the fuel flow rate without causing the above-mentioned problems, and have come up with the present invention.

To achieve the above object, the fuel flow rate detection device of the present invention has a configuration including a pressure sensor that detects when the fuel pressure of the fuel injection pump by the plunger becomes equal to or higher than the opening pressure of the delivery valve; The present invention is characterized in that it comprises a timer for measuring the output time of the detection signal in synchronization with the operation of the pump, and an output means for outputting the fuel flow rate in accordance with the output time.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. That is, the timing means of this embodiment measures time by using an arrangement type injection pump and a pulse generation means that outputs a pulse signal with a frequency proportional to the rotation speed of the plunger drive shaft, and when the delivery valve is opened. a counting means for counting the wave number of the pulse signal outputted from the pulse generating means during a period during which the pulse signal is output from the pulse generating means; a holding means for holding the counting result of the counting means; This is implemented by providing an output means for outputting the data.

FIG. 2 is a sectional view of a bottle type distribution type injection pump equipped with the fuel flow rate detection device of the present invention. Note that the same parts in FIG. 2 as those shown in FIG.

Reference numeral 7 in the figure is a pressure sensor. This pressure sensor 7 operates when the pressure of the fuel during the fuel injection stroke of the plunger 5 (the state shown in FIG. 2) is higher than a predetermined value, that is, higher than the opening pressure of the delivery valve 8. It is installed in a passage 9a branching from an outlet passage 9 between the delivery valve 8 and the outlet passage 9. Also, 1
0 is a rotation sensor that detects the rotation speed of the gear 11, that is, the rotation speed of the pump, and outputs a pulse signal of a number proportional to the rotation speed of the pump. Also, 12 is gear 1
This is a disk having one protrusion 13 fixed to the disk. In addition, 14 is a protrusion 1 of this disk 12.
This is an electromagnetic pickup that outputs one pulse signal every time 3 is detected, that is, every time the pump rotates once.

FIG. 3 is a circuit diagram of the fuel flow rate detection device of the present invention.

In the figure, 16 is an amplifier, 17 is an AND circuit, 1
8 is a multiplier, 19 is a counter, 20 is a latch, 2
1 is a D/A converter.

The pressure waveform of the fuel at the branch point between the outlet passage 9 and the passage 9a is as shown in FIG. 4a. The pressure sensor 7 operates while the delivery valve 8 is open, that is, while fuel is being injected. The signal inputted from this pressure sensor 7 to one input terminal of the AND circuit 17 via the amplifier 16 becomes a signal corresponding to the above-mentioned pressure waveform (see FIG. 4b).

On the other hand, the rotation sensor 10 outputs a signal proportional to the pump rotation speed as shown in FIG. This signal is once input to the multiplier 18 and converted into a pulse signal proportional to the pump rotation speed as shown in d of the figure. The purpose of doing this is to improve the accuracy of the signal. This pulse signal is input to the other input terminal of the AND circuit 17. Then, AND circuit 1
7 outputs a pulse signal shown in e of the figure, that is, a pulse signal generated during the fuel injection time. The amplifier 16, the AND circuit 17, and the multiplier 18 described above are used to count the wave number of the pulse signal output from the pulse generation means during the period when the delivery valve is open, that is, according to the present invention. This was carried out by configuring the counting means as described above.

The pulse signal is input to a counter 19.
The counter 19 receives the signal shown in FIG. The counted signal (see g in the figure) is held by a latch 20, which is a means for holding the counting result by the counter, until the next signal is input from the electromagnetic pickup 14. The signal is then input to the D/A converter 21 and converted into an analog quantity (see h in the figure).
This analog signal corresponds to the fuel flow rate during one engine cycle.

Note that the pressure sensor 7 may be provided in the pressure chamber 22 (see FIG. 2) instead of being provided in the passage between the plunger 5 and the delivery valve 8 as described above. That is, the pressure chamber 22 contains fuel that is compressed during the injection stroke, and the fuel is injected from here through the center passage of the plunger 5 and into each cylinder via the delivery valve. Tsushiya Chamber 22
By detecting the fuel injection time within the pressure chamber 22, the average fuel flow rate of each cylinder can be detected. There is no need to do this, and the structure is simple.

Furthermore, the circuit for determining the fuel flow rate from the operating signal of the pressure sensor 7 is not limited to the one shown in FIG.

As explained above, the fuel flow rate detection device of the present invention includes a pressure sensor that detects when the fuel pressure of the fuel injection pump by the plunger becomes equal to or higher than the opening pressure of the delivery valve, and the output time of the detection signal of the pressure sensor. by a timer that measures time in synchronization with the operation of the pump, and an output means that outputs a fuel flow rate corresponding to the output time, so that the fuel injection time is determined by the opening time of the delivery valve. Since we have adopted a direct timing method that measures time in synchronization with the operating cycle of the fuel cell, it is possible to accurately detect the fuel flow rate with a simple configuration, and the effect is that reliability and durability can be easily increased. can be played.

Although this embodiment has been described using a distribution type injection pump, it goes without saying that it can also be applied to a normal row type injection pump.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of a bottle-type distributed injection pump, Figure 2 is a cross-sectional view of the main parts of a bottle-type distributed injection pump equipped with the fuel flow rate detection device of the present invention, and Figure 3 is a cross-sectional view of the main parts of a bottle-type distributed injection pump. 4 is a circuit diagram of the fuel flow rate detection device of the present invention, and FIGS.
FIG. 3 is a signal waveform diagram at each part of the circuit diagram shown in the figure. 1... Drive shaft, 2... Cam disk, 5... Plunger, 7... Pressure sensor, 8...
... Delivery valve, 10 ... Rotation sensor, 14
...Electromagnetic pick-up, 16...Amplifier, 17...
...AND circuit, 18...multiplier, 19...counter, 20...latch, 21...D/A converter.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A pressure sensor that detects when the fuel pressure of the fuel injection pump by the plunger exceeds the opening pressure of the delivery valve, and the output time of the detection signal output by the pressure sensor. A fuel flow rate detection device comprising: a timer that measures time in synchronization with the operation of the pump; and an output means that outputs a fuel flow rate in accordance with the output time. (2) The timing means includes a pulse generation means that outputs a pulse signal with a frequency synchronized with the operating cycle of the fuel injection pump, and a wave number of the pulse signal outputted by the pulse generation means during a period when the delivery valve is open. A utility model registration request characterized in that a counting means for counting, a holding means for holding the counting result of the counting means, and an output means for outputting the counting result when the relevant cycle of the pump is completed. The fuel flow rate detection device described in scope item (1).