JPS5840266Y2 - Supercharged diesel engine with low compression ratio - Google Patents

Description

[Detailed description of the invention] This invention is a supercharger with a low compression ratio that automatically operates an exhaust throttle valve depending on the conditions of the intake air taken into the engine, the engine load, and the cooling water temperature conditions. Regarding diesel engines.

When increasing the output of a diesel engine, the maximum combustion pressure Pma
As x increases and Pmax increases, stress in diesel engine parts increases, requiring design changes and increasing costs.

Therefore, in order to increase the output while keeping Pmax as low as possible, the compression ratio is lowered.

However, if the compression ratio is lowered, starting performance and low-load performance will deteriorate, so to prevent this, an exhaust throttle valve is installed.
The operator manually operates this valve according to engine startup and load, but adjusting the opening requires skill, and if the operator forgets to adjust the opening, it may cause an increase in engine exhaust gas temperature or knocking. There is a button that causes problems such as deterioration of engine performance.

The present invention was made with the aim of eliminating the above-mentioned drawbacks of the conventional means, and includes a temperature switch that operates when the temperature of intake air is below a certain temperature and outputs a signal to a first AND circuit; a temperature switch that operates depending on the cooling water temperature of the ring, and if the cooling water temperature detected by the temperature switch is lower than a reference temperature, a signal is output to the first AND circuit, and if it is higher than the reference temperature, a signal is output to the OR circuit. a circuit that outputs a signal to the engine, a pressure switch activated by the high-pressure supercharging air pressure entering the engine, and a circuit that outputs a signal from the first AND circuit when the high-pressure supercharging air pressure detected by the pressure switch is lower than the reference pressure. a second AN that can input signals of
a circuit that outputs a signal to the D circuit and outputs a signal to the OR circuit when the high pressure supercharging air pressure is higher than the reference pressure;
A circuit that outputs a signal to throttle the exhaust throttle valve provided in the supercharger exhaust pipe in response to a signal from the second AND circuit, and a signal to open the exhaust throttle valve in response to a signal from the OR circuit. The device is characterized in that it is provided with a circuit.

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

In the figure, 1 is an intake pipe, and 2 is an exhaust pipe. Between the intake pipe 1 and the exhaust pipe 2, cylinders 3 of the engine are connected in parallel.

4 is a low-pressure supercharger, 5 is a low-pressure air cooler, 6 is a high-pressure supercharger, 7 is a high-pressure air cooler, 8 is an exhaust throttle valve attached to the exhaust pipe 2, 9 is intake air, and 10 is an exhaust air cooler. It's gas.

The exhaust throttling control system is shown in FIG. The high-pressure supercharging air pressure entering the engine from 6 is set to a predetermined set pressure (in this example,
G) It is designed to operate in the above cases.

12 is a timer; 13 is an alarm that warns of poor control of the exhaust throttle valve 8;

14 is a temperature at which the temperature of the intake air is constant (in this example, 3
15 is a circuit that issues a command signal to throttle the exhaust throttle valve 8; 16 is a throttle switch that detects the closed position of the exhaust throttle valve 8; 17;
is an indicator lamp that flashes to indicate that the exhaust throttle valve 8 is being throttled.

Furthermore, 18 is a temperature switch that is activated when the cooling water temperature of the cylinder 3 exceeds a predetermined set temperature (40° C. in this embodiment), and 19 is a temperature switch that outputs a 0VER signal when the temperature switch 18 is activated. Temperature switch 18 is activated L
%・caseK)−! This is a circuit that outputs a BELOW signal.

Furthermore, like the pressure switch 11, 20 is a pressure switch installed at a predetermined position in the cylinder 31 from the outlet side of the high-pressure supercharger 6, for example, in the intake pipe 1, and the pressure switch 20 exits from the high-pressure supercharger 6 and enters the engine. It is activated when the high-pressure supercharging air pressure reaches a predetermined set pressure (0.3 kg/CrrL2G in this example).

21 outputs a 0VER signal when the pressure switch 20 operates, and outputs a B signal when the pressure switch 20 does not operate.
A circuit that outputs the ELCyyV signal, 22 and 23 are timers, 24 is a circuit that outputs a signal to open the exhaust throttle valve 8, and 25 is a throttle switch that detects the fully open state of the exhaust throttle valve 8;
26 is an indicator lamp that flashes to indicate that the exhaust throttle valve 8 is being opened; 27.28.29.30;

31 is an AND circuit, and 32 is an OR circuit.

Among the AND circuits 27, 28, 29, 30, and 31, the M circuit 28 is the first one in the description of the utility model registration claim.
The AND circuit 29 is also called a second AND circuit in the claims of the utility model registration.

Press the button at startup and under low load, and the temperature of the intake air is 30.
℃ or less, ■Cylinder cooling water temperature is 40℃ or less, ■High-pressure supercharging air pressure entering the engine is 0.3Kg/cm2C or less.
is narrowed down.

That is, when the intake air temperature is below 30°C, the temperature switch 14 is activated and a signal is sent to the AND circuit 28, and when the cooling water temperature of the cylinder 3 is below 40°C, the temperature switch 18 is not activated. , the BELOW signal is sent from the circuit 19 to the AND circuit 28, and when both signals enter the AND circuit 28, a signal is sent from the AND circuit 28 to the AND circuit 29.

On the other hand, when the high-pressure supercharging air pressure is 0.3 kg/σ or less, the pressure switch 20 does not operate and the circuit 21 outputs B
The ELOW signal is sent to the AND circuit 29 via the timer 23.

Since all of the conditions (2), (2), and (3) are satisfied, a signal is sent from the AND circuit 29 to the circuit 15, and the circuit 15 outputs a signal to throttle the exhaust throttle valve 8. The exhaust throttle valve 8 is throttled.

In addition, when the exhaust throttle valve 8 is throttled, the limit switch 16 is activated, and the signal output from the limit switch 16 is sent to the indicator lamp 17.

Therefore, the indicator lamp 17 lights up to indicate that the exhaust throttle valve 8 is throttled.

When the throttle valve 8 is further throttled, the limit switch 16 outputs a closing signal for the valve 8 to the AND circuit 27. 0.5 in the case of the example
K9/cm 2 G) or more, so as mentioned above, if the high pressure supercharging air pressure is 0.5
Kg/cm2 If the pressure is below G, press the pressure switch 1.
1 does not work.

Therefore, since no signal is sent from the pressure switch 11 to the AND circuit 27, the AND circuit 27 is not established, and no signal is output from the AND circuit 27 to the alarm 13.

Therefore, the alarm 13 does not issue a warning.

By controlling as described above, when the diesel engine is started and the load is low, the exhaust throttle valve 8 is throttled to allow exhaust gas to flow backward during the intake stroke, increasing the compression line temperature in the cylinder 3 and facilitating ignition. I will finish it.

When the load on the engine increases, the temperature of the cooling water in the cylinder 3 or the high-pressure supercharging air pressure at the engine inlet increases, and one of the conditions (1) or (2) exceeds the set value.

Then, the temperature switch 18 is activated depending on the cooling water temperature, or the pressure switch 20 is activated depending on the high pressure supercharging air pressure.
Each operates.

For example, when the cooling water temperature of the cylinder 3 is higher than the set temperature (40°C), the temperature switch 18 is activated and a signal is output to the circuit 19, and the 0VER signal is ORed from the circuit 19.
The signal is sent to circuit 32.

Also, the high pressure supercharging air pressure is the set pressure (0.3Kg/cm 2
G) In the above case, the pressure switch 20 is activated and a signal is output to the circuit 21, and a 0VER signal is sent from the circuit 21 to the OR circuit 32.

Then, when a signal is sent from either circuit 19 or 21 to the OR circuit 32, the signal is sent from the OR circuit 32 to the circuit 24 which issues a signal to open the exhaust throttle valve 8, and from the circuit 24 When a command to fully open the throttle valve 8 is issued, the exhaust throttle valve 8 becomes fully open.

When the exhaust throttle valve 8 is fully opened, this is detected by the limit switch 25, and an instruction is given from the limit switch 25 to the indicator lamp 26, which lights up to clearly indicate this fact.

If the temperature of the cooling water in the cylinder 3 is higher than the set temperature of the temperature switch 18, no signal is output from the circuit 19 to the AND circuit 28, and therefore no signal is output from the AND circuit 28.

Further, when the high-pressure supercharging air pressure is higher than the set pressure of the pressure switch 20, no signal is output from the circuit 21 to the AND circuit 29, and therefore, no signal is output from the AND circuit 29.

For example, suppose that the exhaust throttle valve 8 does not open due to a malfunction in the control system even though either of the conditions (1) or (3) exceeds the set value.

In this case, the high pressure supercharging air pressure is 0.5 kg/c
When the pressure exceeds m 2 G, the pressure switch 11 is activated and a signal is sent to the AND circuit 27.

On the other hand, since the exhaust throttle valve 8 was previously throttled without opening, the limit switch 16 outputs a signal to close the exhaust throttle valve 8.
This is one trench sent to D circuit 27.

Therefore, even though the exhaust throttle valve 8 should be open, the high-pressure supercharging air pressure is 0-5 Kf/c when the exhaust throttle valve 11 is closed.
m''G is exceeded, the pressure switch 11 and limit switch 16 send a signal to the AND circuit 27, and the AN
An alarm 135 signal is output from the D circuit 27, and the alarm 13 issues an alarm.

The reason why the timers 22, 23, and 12 are provided is that the high-pressure supercharging air pressure on the downstream side of the high-pressure supercharger 6 pulsates and the pressure switch 20.11 changes between the operating state and the non-operating state (ON, 0FF) in short cycles. This is to prevent repetition.

The specific conditions for opening and closing the throttle valve in the embodiment of the present invention are determined from the test results depending on the engine type, and are limited to the case of two-stage supercharging as shown in Fig. 1, and the conditions for single-stage supercharging. It goes without saying that the present invention can be applied to any vehicle, and that other changes can be made within the scope of the vehicle design.

Since the supercharged diesel engine with a low compression ratio of the present invention has the above-described configuration, it exhibits various excellent effects as described below.

(I) The compression ratio can be lowered without deteriorating start-up performance and low-load performance.

(n) Good starting performance.

(2) Reduces knocking due to ignition delay at low loads,
Moreover, the exhaust gas concentration at low load is reduced.

■ No performance deterioration under high loads.

M It is possible to save labor by eliminating the need for the operator to operate the exhaust throttle valve.

M) There is no need for the driver to consciously try to drive smoothly manually, and all controls are performed continuously and automatically.

Therefore, it is easy to operate.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a supercharged diesel engine with a low compression ratio according to the present invention, and FIG. 2 is a block diagram of a control system for an exhaust throttle valve used in the diesel engine of FIG. 3 is a cylinder, 4 is a low pressure supercharger, 5 is a low pressure air cooler,
6 is a high-pressure supercharger, 7 is a high-pressure air cooling device, 8 is an exhaust throttle valve, 11.20 is a pressure switch, and 14° and 18 are temperature switches.

Claims (1)

[Scope of utility model registration request] A temperature switch that operates when the intake air temperature is below a certain temperature and outputs a signal to the first AND circuit, a temperature switch that operates depending on the cylinder cooling water temperature, and a cooling water temperature detected by the temperature switch. A circuit that outputs a signal to the first M (e) circuit when the temperature is lower than the reference temperature and outputs a signal to the OR circuit when it is higher than the reference temperature, and a pressure operated by the high-pressure supercharging air pressure entering the engine. and a second AND circuit which can input the signal from the first AND circuit when the high-pressure supercharged air pressure detected by the pressure switch is lower than the reference pressure, and outputs a signal to the high-pressure supercharged air. When the pressure is higher than the reference pressure, a signal is output from a circuit that outputs a signal to the OR circuit and a signal from the second AND circuit to throttle the exhaust throttle valve provided in the turbocharger exhaust pipe. A supercharged diesel engine having a low compression ratio, comprising: a circuit for outputting a signal for opening the exhaust throttle valve in response to a signal from the OR circuit;