JPS6145305Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an intake passage device for reducing combustion noise during low-speed, low-load operation of a diesel engine, including idling operation. This relates to a valve control mechanism.

FIG. 1 is a sectional view showing the structure of an intake passage device for a diesel engine previously proposed by the applicant. In this figure, 1 is a cylinder head of a diesel engine, 2 is an intake valve, 3 is an intake manifold, and 4 is an air cleaner connected to the starting end of the intake manifold 3. Reference numeral 5 designates a main passage for intake air, and an intake throttle valve 6 for adjusting the amount of intake air is provided in this main passage 5, and this intake throttle valve 6 is controlled by a diaphragm valve 22 as shown in FIG. It is fully closed during idling operation. 7
is an intake sub-passage, which is attached to the intake manifold 3 by a flare nut 8. An intake air heating section (pipe) 9 is provided on the outer periphery of the sub passage 7, and engine cooling water is introduced into a passage 10 of the intake air heating pipe 9 to heat the sub passage 7.
Therefore, when the engine is in idle operation or low speed/low load operation, the intake throttle valve 6 is either fully closed or its opening is very slightly restricted, so that most of the air taken into the engine flows through the auxiliary passage. 7, the air (a small amount) taken into the engine is warmed and the piston compression start temperature becomes high. Therefore, the temperature of the intake air is greatly increased by piston compression, and the fuel injected into the cylinder immediately starts combustion, which prevents a sudden increase in cylinder pressure due to ignition delay, and reduces idle operation and low speed. - Reduces engine vibration and noise during low-load operation.

Next, the control mechanism of the intake throttle valve 6 will be described based on FIG. In Figure 2, 11 is battery;
A key switch 12 includes a preheating switch 12a and a starter switch 12b. 13 indicates a glow plug.

When starting the engine, when the key switch 12 is switched from the stop position to the operating position, the preheating switch 12a is activated.
is closed and the glow plug 13 is heated. Next, when the glow plug 13 is heated, the starter switch 12b is closed by switching the key switch 12 from the operating position to the starting position. Therefore, the coil 14a of the starter relay 14 is excited, the contact 14b is closed, and the starter motor 15 is started.
Start by cranking. The accelerator switch 16 is in contact with a cam 17 that rotates around a camshaft 17a according to the amount of depression of an accelerator pedal (not shown), and is turned on in low speed and low load ranges, including idling operation with a small amount of depression of the accelerator pedal. It is configured to turn off in other operating ranges. Since the accelerator switch 16 is on in the low speed/low load range including idling, the solenoid valve 18 is activated, the valve element 18a is pulled down, the passage 18b is opened, and the passage 18c is activated.
cut off. Therefore, the negative pressure generated by the vacuum pump 20 in conjunction with the alternator 19 is introduced from the vacuum tank 21 through the passage 18b into the negative pressure chamber 22a of the diaphragm valve 22, and the valve body 2
Pull up 2b. As a result, the intake throttle valve 6 blocks the intake passage 5 and supplies air from the sub passage 7.
In operating ranges other than low speed and low load ranges, including idling, the accelerator switch 16 is turned off, the valve body 18a of the solenoid valve 18 blocks the passage 18b, and the passage 1
8c is opened, the atmosphere is introduced into the negative pressure chamber 22a of the diaphragm valve 22, the intake throttle valve 6 is opened, and air is supplied through the main passage 5. (For example, see Japanese Utility Model Application No. 55-35372.) However, in such a conventional intake throttle valve control mechanism, the intake throttle valve 6 is configured to be fully closed even during startup and warm-up. (1) The amount of intake air decreases, the compression pressure decreases,
The end-of-compression temperature is correspondingly lower, resulting in poor startability.

(2) When the engine is cold, compression pressure and excess air ratio decrease, combustion conditions worsen and white smoke increases.

There was a problem.

This invention was developed with a focus on these conventional problems, and it solves the above problems by detecting a signal indicating the engine status at startup and warm-up, and controlling the intake throttle valve to the open state. It aims to solve the problem.

This invention will be explained in detail below based on the drawings.

FIG. 3 is a block diagram showing an embodiment of this invention. In FIG. 3, 23 is a NAND circuit, and 24 is a thermoswitch that detects the engine representative temperature, such as water temperature, or a starter start signal detector that detects when the engine starts, and these control means control the opening and closing of the intake throttle valve 6. is configured. And thermo switch 24
is configured to turn off when the temperature is below the set temperature and turn on when the temperature is above the set temperature (after warming up). In addition,
Other same reference numerals as in FIG. 2 indicate the same components.

Next, the effect will be explained. An "H" level signal is always sent to the a terminal of the NAND circuit 23. When starting, the starter switch 12b of the key switch 12
When the coil 14 of the starter relay 14 is closed,
Since the contact a is excited and the contact 14b is closed, an "H" level signal is also sent to the b terminal of the NAND circuit 23, and the output of the NAND circuit 23 becomes "L" level. Therefore, at the time of starting, the signal to the solenoid valve 18 is cut off regardless of whether the thermo switch 24 and the accelerator switch 16 are on or off, and the valve element 18a opens the passage 18c and blocks the passage 18b.
Atmospheric air is introduced into the negative pressure chamber 22a of the diaphragm valve 22, and the intake throttle valve 6 is fully opened. Since the starter switch 12b is opened except when starting, the contact 14b of the starter relay 14 is opened, and the b terminal of the NAND circuit 23 becomes "L" level, so the output of the NAND circuit 23 becomes "H" level. . However, when the engine is cold, the thermo switch 24 is turned off when the engine representative temperature, for example, the water temperature, is below the set temperature, so air is introduced into the negative pressure chamber 22a as described above, and the intake throttle valve 6 is fully opened. Next, when the engine warms up and reaches a temperature higher than the set temperature of the thermoswitch 24, the thermoswitch 24 is turned on. Therefore, since the accelerator switch 16 is turned on in a low speed/low load range including idling operation, the valve body 18a of the solenoid valve 18 shuts off the passage 18c and opens the passage 18b, so that the vacuum tank 21 is placed in the negative pressure chamber 22a. negative pressure is introduced, and the intake throttle valve 6 is kept fully open.

As explained above, this invention detects signals indicating the engine status during startup and warm-up, such as the starter start signal and the typical temperature of the engine such as water temperature, and controls the intake throttle valve to the open state. Since the configuration is provided with a control means for controlling the intake throttle valve to a closed state when the representative temperature becomes equal to or higher than the set temperature and during low speed/low load operation including idling operation, the control means is provided for controlling the intake throttle valve to the closed state. It is possible to improve the starting time while reducing combustion noise under load, and to prevent an increase in white smoke during warm-up.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of an intake passage device previously proposed by the applicant, FIG. 2 is a configuration diagram illustrating the control mechanism of the intake throttle valve shown in FIG. 1, and FIG. FIG. 1 is a configuration diagram showing an embodiment of this invention. In the figure, 5 is a main passage, 6 is an intake throttle valve, 7 is a sub passage, 23 is a NAND circuit, and 24 is a thermoswitch.

Claims (1)

[Scope of utility model registration request] The intake passage is configured into two systems: a main passage and a sub-passage equipped with an intake air heating section having a smaller cross-sectional area,
An intake throttle valve that can variably adjust the cross-sectional area of the main passage is provided in the main passage, and in a low speed/low load range of the engine, the main passage is throttled so that almost the entire amount of intake air is supplied from the sub passage. An intake passage device for a diesel engine configured as described above, further comprising a control means for detecting a signal indicating an engine state and controlling the intake throttle valve to an open state at startup and warm-up based on the signal. Engine intake passage device.