JPS5825526A - Car knock preventive device of diesel engine - Google Patents

Abstract

PURPOSE:To prevent a car knock and improve smoke and driving performance, by providing a vibration detector, detecting vibration of a car body, and a brake device, applying a brake to a control rack of an injection pump. CONSTITUTION:A vibration detector 11 is provided to a car body, and a band- pass filter 13 passes only a frequency of natural oscillation of a car knock. When output voltage of an integrator 15 exceeds a preset value in a comparator 16, a brake is applied to a control rack 2 of a fuel injection pump through a power trasistor Tr and solenoid valve 10. In this way, a car knock can be prevented, while smoke and driving performance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a car knock prevention device for a diesel engine.

One of the drawbacks of diesel engines is the so-called car knock phenomenon. A car knock is when the car does not move smoothly when you press the accelerator, but it suddenly stops when you press the accelerator a little, or suddenly accelerates to a high speed after pressing the accelerator a little, or when the car accelerates too much and you release the accelerator. When the vehicle slows down too much, the speed of the vehicle speeds up or slows down, resulting in a jerking phenomenon. The reason for this is that in the case of a diesel engine, the vehicle's running speed is determined by the amount of fuel injected.
However, the amount of fuel injected does not change smoothly according to the amount of accelerator pedal depression, and a large amount of fuel is suddenly injected just by pressing the accelerator a little, or if you release the accelerator to reduce this large amount of injection. This is because the injection amount decreases rapidly. Therefore, in order to prevent car knock, it is necessary that fuel be injected smoothly according to the amount of depression of the accelerator. The relationship between the control rack for adjusting the injection amount of the injection pump and the fuel injection amount is essentially that if the position of the control rack is constant, it is not related to the engine speed (ideally, the amount of fuel injection should be one foot). , curve X even though the position of the control rack is actually constant K as shown in Fig. 1.

Like Y and Z, the injection amount Q changes depending on the engine rotation speed N. In Figure 1, if the control rack is currently in position ZK and the car is traveling at 40 ra/h as a mermaid, and you want to increase the speed to 50 ra/h, when you step on the accelerator, the fuel at point A7 is Even though the injection amount should be sufficient, the injection amount may reach point B due to the characteristics of the injection pump. Therefore, if you reduce the amount of accelerator pedal depression to reduce this injection amount, A
Instead of going back one point, it goes back to point C and K. In other words, if the loop of A-B-4 & → C → person is repeated, the fuel injection amount becomes K, and the running speed of the car is 40.
It repeatedly goes back and forth between &/h and 50 m/h and is unstable. Conventionally, in order to eliminate such a car knock phenomenon, the car knock phenomenon was reduced by comprehensively adjusting the characteristics of the injection pump, the injection pump, the control lever, the accelerator, etc. In particular, methods such as ■ adjusting the specifications of the injection system to be less likely to cause car knocks, and ■ adding a brake to the control rack of the injection pump can be considered, but method (■) also prevents smoke from worsening. However, since method (2) has the disadvantage of easily causing deterioration of driving performance, a method that is compatible with both parties has been recommended, but it has not been satisfactory.

Therefore, the present invention detects car knock from vehicle vibration and applies braking to the control rack of the injection pump only when car knock occurs, thereby preventing car knock and deteriorating smoke and driving performance. The purpose of the present invention is to provide a car knock prevention device that is free of car knocking.

Next, one embodiment of the car knock prevention device according to the present invention will be described in detail with reference to the drawings.

Figure 2 is a diagram showing the control system of the car knock prevention device.
is the engine's fuel injection pump, 2#f is the control rack for increasing or decreasing the injected fuel, black is the governor, and 4 is the lever. One end 4' of the lever 4 is connected to the accelerator.

S is the dash pot, which is installed between the end of the control model rack of the injection pump and the diameter 7 ram 6, and is a sealed part! 7 is a spring.

The dial 7 ram 6 is pressed in the direction of the control rack 2. s+ is a pipe connected to the dashi ^bot) 5, and the skeleton pipe is equipped with a solenoid valve 10 that connects the closed chamber of the dashpot to the atmosphere. 9 is connected to the dashpot like pipe 8, and has a hole much smaller in diameter than pipe 8. Reference numeral 11 denotes a vibration detector, and a well-known type such as one using a piezoelectric element or a strain gauge type is used.

Reference numeral 12 denotes an amplifier, which may be any known amplifier as long as it has a frequency band that can faithfully amplify the Kerknock signal from the vibration detector. Reference numeral 15 denotes a bandpass filter, which has the function of passing only the signal having the Kernock-specific frequency from among the output signals of the vibration detector amplified by the amplifier. 14 is a rectifier for rectifying the output signal from the band-wave converter. 15 is an integrator for integrating the output signal of the rectifier 14. A comparator 16 is set by adjusting a reference voltage Ha and a variable resistor 1js so that an output is generated when the output voltage of the integrator exceeds a certain value. Tr is a power transistor which becomes conductive upon receiving the output signal from the comparator 16, and causes current to flow through the drive coil of the solenoid valve 10 connected to its collector; VB is the power supply; R is the power transistor.
indicates a resistance, and C indicates a capacitor.

Next, the operation of the above embodiment will be explained with reference to FIG. In FIG. 2, when the accelerator (not shown) is pressed to move the control rack, the amount of fuel injection increases or decreases, and when a car knock occurs as described above, the vehicle body vibrates back and forth at its natural frequency. This vibration causes the vibration detector to generate an output signal, but since automobiles also vibrate due to engine vibrations, unevenness of the road surface, etc., the output signal of the vibration detector 11 is as shown in Fig. 5 (a).
The result is a vibration signal containing many different frequencies, such as . When the signal from the vibration detector is amplified by an amplifier 12 and passed through a bandpass filter, it becomes a signal with a vibration frequency unique to Curnock, as shown in FIG. 3(b). This carnock-specific signal is rectified by the rectifier 14, and is shown in FIG.
This results in a pulsating DC signal as shown. This DC signal is integrated by an integrator 151C and increases as time passes as shown in FIG. This integrator 1
When the output signal 5 becomes larger than the preset magnitude of car knock vibration, the comparator 16 outputs an output, turns on the transistor Tr, operates the solenoid valve 10, and closes the solenoid valve 10. When the solenoid valve 1° is closed, the secret room of Darashi Island Bot 5 is a small hole office 9.
Because it is in contact with the atmosphere only through As the current changes, the driving of the car gradually becomes more stable. When the Kerknock vibration subsides, the input to the integrator is cut off, the output of the integrator gradually decreases as shown in the iris diagram), the transistor Tr becomes non-conducting again, and the solenoid valve 10 is opened. Therefore, the action of the dash pot 5 as a damper disappears, and the control rack begins to move in response to the accelerator again.

As explained in detail above, the car knock prevention device according to the present invention installs a vibration detector on the body of a vehicle, selects only the vibration frequency output due to the car knock unique to the vehicle from the output of this vibration detector, and prevents the car knock from occurring. After converting into a first-flow signal with a magnitude corresponding to the magnitude of vibration, this converted DC signal is integrated using an integrator, and when the integrated amount exceeds a preset external value, the injection pump starts fuel injection. We applied a brake to the control rack that adjusts the amount, and automatically released the brake when the car knock subsided.
Unlike conventional car knock prevention devices, there is no misalignment such as deterioration of smoke, and there is no deterioration in driving performance.
It operates only when a car knock occurs and exhibits the outstanding effect of effectively eliminating the car knock.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between engine speed and fuel injection amount when the control rack lid is kept constant, Fig. 2 is a control system diagram of the car knock prevention device according to the present invention, and Fig. 5 is a vibration detection FIG. 3 is a diagram for explaining processing of an output signal from the device. 1. Fuel injection pump, 2. Control rack, 5.
... Capana, 4... Lever, 5... Dash, Bo, To, 6... Diaphragm, 7... Spring, 8...
Pipe, 9... Office, 10... Solenoid valve, 11
... Vibration detector, 12... Amplifier, 15... Bandpass filter, 14... Rectifier, 15... Integrator, 16...
... Comparator, Tr... Transistor J-1R... Resistor, C... Capacitor. Patent applicant: Isuso Jidosha Co., Ltd. Representative Patent Attorney Sangai Tsuji (2 persons)

Claims (1)

[Claims] a detector for detecting vibrations of a vehicle body; a selection circuit for selecting only a vibration frequency output due to a car knock unique to the vehicle from the output of the detector; and a control circuit for issuing an output when the output of the selection circuit exceeds a predetermined value; A car knock prevention device for a diesel engine, comprising a braking device that applies braking to a control rack of a fuel injection pump using the output of the control circuit.