JPS58195035A - Device for adjusting maximum pressure in engine cylinder for diesel engine - Google Patents

Abstract

PURPOSE:To enhance responsive performance, by providing an injection timing setting unit for controlling fuel injection timing, so that abrapt increase in Pmax is avoided in the condition of transient operation for moderating the limiting value of a stopper. CONSTITUTION:The Pmax which is detected by an engine cylinder pressure transmitter 9 is compared with a Pmax set value in an engine cylinder maximum pressure comparator Pmax for obtaining a deviation DELTAP which is then introduced into a converter 3 for converting it into an adjusting amount signal of injection timing. The signal operates an actuator 4 so that a new injection timing is set by means of the timing adjusting device of a fuel injection pump 5. The thermal load of the engine is very moderately increased since the timing control is brought about even if a fuel amount Q is increased, thereby responsive performance is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a maximum cylinder pressure regulating device for a diesel engine.

In diesel engines that use a jerk-type fuel injection pump, the fuel injection timing is determined by the shape of the pump's silant lead. on the other hand.

The maximum cylinder pressure of the engine (hereinafter abbreviated as Pmax) depends on the fuel injection timing, so as shown in Figure 1,
The PmaX characteristics are constant depending on the various lead shapes. In FIG. 1, 01 is an injection start control lead, and 02 is an injection path control lead.

Therefore, these devices have the following drawbacks.

(1) The fuel efficiency (fuel consumption rate) of a diesel engine is P
(In one example, if ax increases P by 5 kg/c-, the fuel consumption will be approximately 1 gA
) S-Hax is said to improve). Engine load conditions (e.g.
In the case of marine vessels, PmIILx fluctuates due to the size of cargo, dirt on the hull, ambient conditions such as disturbance, etc.) or changes over time, and it is not always possible to maintain the optimum PmaX.

(2) The use of fuel oil with poor ignitability, indicated by the teasel index or cetane number, increases the Prrla
X change occurs. In extreme cases, Pmax rises above the engine's allowable level, and it is necessary to reduce the load to protect the engine.

(3) Under transient operating conditions such as when a ship increases speed, turns, or in rough weather, the load temporarily increases, resulting in a so-called overload state. do.

(4) On the other hand, in recent low fuel consumption engines, (c) in Figure 1
A reed-shaped injection pump as shown in the figure has been put into practical use, and the optimum i'max is obtained at the normal output. However, the normal output level on the ship is 75%, 8
0%...90 inches, and if the lead shape is changed each time, the number of types increases, causing problems in manufacturing management.

Note that +Pmax can be changed by adjusting the fuel cam, but in the case of item (2) above.

It is cumbersome to do this every time you refuel, and in reality it often limits the load.

The purpose of the present invention is to provide a diesel engine maximum in-cylinder pressure regulating device that is capable of achieving low fuel consumption in one engine, automating maximum adjustment, and improving performance in transient conditions, focusing on the above points. The feature is that the engine speed, the amount of fuel injected into the cylinder, the pressure of air supply into the cylinder, and the heat generation rate in the cylinder are inputted to each signal, and the optimum cylinder maximum is calculated. A maximum cylinder pressure calculator that calculates the pressure, and a maximum cylinder pressure comparator that receives signals from the above-mentioned optimal maximum cylinder pressure and the actual maximum cylinder pressure and calculates the deviation between the two.

The above deviation Nobutoyo is input, and the injection timing adjustment amount corresponding to the above optimal cylinder maximum and high pressure is set, and the signal of the adjustment amount is transmitted to the □ actuator, and the fuel injection pump injects 1.
It is equipped with an injection timing setting device that controls injection timing.

In other words, (1) a calculation and setting mechanism is provided that can set the optimum 'max so that the fuel efficiency is the lowest under all operating conditions and operating modes of the engine, and (2) fuels with different combustion characteristics such as ignitability are provided. (3) In an overload state, a stopper was conventionally provided to detect the amount of fuel that increases as the load increases.

In order to avoid a sudden increase in Pmax during transient operating conditions, response performance was improved by loosening the Stone-Taira limit values in response to the decrease in thermal load.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is an explanatory diagram showing one embodiment of the apparatus according to the present invention.

In the figure, 1 is a controller, that is, a cylinder maximum pressure calculator that calculates the optimum cylinder maximum pressure, 2 is a cylinder maximum pressure comparator, 3 is a converter, that is, an injection timing setting device, and 4 is an actuator (injection timing (for setting), 5 is a fuel injection pump with variable injection timing adjustment device, 6 is a fuel position transmitter,
7 is a supply pressure transmitter, 8 is a rotational speed transmitter, and 9 is an in-cylinder pressure transmitter.

10 is a heat release rate calculator, and 11 is a PmaX adjustment limit setter.

The controller 1 receives the fuel injection amount Q from the fuel position transmitter 6.
9 rotation speed n from rotation speed transmitter 8, air supply pressure transmitter 7
The upstream supply air pressure P, and the heat release rate dcv'dθ calculated by the calculator 1 ( ) based on the change in the cylinder pressure are input. In addition, dQ/dθ=P Ppyu+-! -■-.

RdORdθ And the max characteristic is the above fuel injection amount Q99 engine speed n
, function Pmax of supply pressure P8 and heat release rate dQ//dθ
= / (Q, n, P8- dQ/dθ), and the optimum Pm1Lx under the operating conditions is Pm
Output to ax comparator 2.

For example, when a certain heat release rate dQ/dθ and supply air pressure P8 are given, a Pmax characteristic function as shown in FIG.
The optimum setting value is determined in order to increase aX. At that time”m
As shown in FIG. 3, ax is constrained by various limit lines that take into account the permissible in-cylinder pressure, the upper limit of exhaust temperature, the occurrence of non-king, etc. Therefore, PmaX is set within the limits indicated by diagonal lines in FIG.

This limit line can be easily changed using the setting device 11, facilitating adjustment.

Improved practicality. When the heat release rate dQ/dθ changes, the max characteristic function changes each time, so another function table is applied and the optimum Pmax setting value changes.

On the other hand, the actual Pm1L detected by the cylinder pressure transmitter 9
x is compared with the Pmax set value by the in-cylinder maximum pressure comparator 2, and the deviation ΔP = (Pmax detected value) - (Pmax set value) is determined.

The deviation ΔP is input to the converter 3 and converted into an injection timing adjustment amount signal Δθinj. The signal Δθinj operates the actuator 4, and the timing adjustment device of the fuel injection cylinder f5 sets a new injection timing:: Δθilj. □ The above operation compensates for the new ・'It"1yta x, and the set value and actual value become equal.

Therefore, the conventional type has PmaX due to the difference in fuel properties.
However, in the present invention, the timing is automatically adjusted so as to always maintain the set value of Pmax.

Furthermore, in a transient state, the fuel amount Q is controlled by the operation of the speed governor, but in the conventional system, as the load increases, the fuel amount Q is immediately set to the stopper position, which causes The pressure was rising too high. However, in the present invention, functions other than the fuel amount Q, that is, the rotation speed n,
Even if the fuel amount Q increases due to the effect of the air supply pressure P8, P
Timing control works to suppress the rate of increase ix.

The increase in heat load on the engine will be very gradual compared to the conventional one.

Also, according to the present invention, the fuel injection ponzosolanger only requires setting the fuel amount, so if a sufficient amount of fuel can be secured (securing the discharge stroke), one lead shape can be used.
We can meet a wide range of required specifications. , j Note that this variable injection timing adjustment device can be used regardless of whether it is an electronic type or a mechanical type.

Furthermore, the ``max calculation general constant adjustment mechanism'' can also be applied to land engines by changing the Pmax characteristic function.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the lead shape and Pmax characteristics, and FIG. 2 is an explanatory diagram showing one embodiment of the device according to the present invention. FIG. 3 is a diagram showing an example of the PmaX characteristic function. l... Maximum cylinder pressure calculator, 2... Maximum cylinder pressure comparator, 3... Injection timing setter, 4... Actuator, 5... Fuel injection pump, 6... Fuel Position transmitter, 7... Supply pressure transmitter, 8... Rotation speed transmitter, 9... In-cylinder pressure transmitter, io... Heat release rate calculator, 11... PmaX adjustment limit Setting device. Lead shape p max Poetry section maximum 1% pressure injection amount 1 (￥)

Claims (1)

[Claims] ■ Signals of the engine rotational speed, the amount of fuel injected into the cylinder, the pressure of air supply into the cylinder, and the rate of heat generation in the cylinder are each input to calculate the optimal maximum cylinder pressure. A maximum cylinder pressure comparator receives the signal of the optimum maximum cylinder pressure and the actual maximum cylinder pressure and calculates the deviation between the two, and a maximum cylinder pressure comparator receives the signal of the above deviation and calculates the optimum cylinder pressure as described above. Injection corresponding to the highest pressure in the cylinder. A maximum in-cylinder pressure regulating device for a diesel engine, comprising an injection timing setting device that sets a timing adjustment amount and transmits a signal of the adjustment amount to an actuator to control injection timing of a fuel injection pump.