JPS6226598Y2 - - Google Patents

Description

[Detailed description of the invention] This invention connects a brake booster of a vacuum braking force amplification device to a negative pressure generating device such as a vacuum pump driven by an engine via a brake side piping system, and The present invention relates to an automatic stopping device for a diesel engine that is connected to a diaphragm device for automatically stopping the engine via an automatic stopping piping system.

A device of this kind has been proposed as described in Japanese Utility Model Application Laid-Open No. 52-148830. This prior art is based on the first
As shown in the figure, a negative pressure generator d is constructed by connecting a negative pressure tank c to a vacuum pump b driven by an engine a, and a vacuum control system is connected to the negative pressure tank c via a brake side piping system e. A brake booster f of a power amplification device is connected to the brake booster f, and a diaphragm device h for automatic engine stop is connected via an engine automatic stop side piping system g. v is a three-way solenoid valve placed in the middle of piping system g on the engine automatic stop side,
This is switched by turning the starter key switch (hereinafter referred to as the key switch) on and off.
When the key switch j is turned OFF, the negative pressure in the negative pressure tank c is guided to the diaphragm device h, and by operating the diaphragm device h, the operating lever l of the shutoff valve provided in the fuel passage of the fuel injection pump k is operated to close. , the fuel is cut and the engine a is stopped.

By the way, the engine automatic stop side piping system g
Generally, rubber hoses are used as conduits, so there is a high risk that the rubber hoses will come off or break and be exposed directly to the atmosphere. At this time, the suction capacity of the vacuum pump b of the negative pressure generator d becomes insufficient, and the degree of vacuum in the brake booster f decreases, causing the vacuum braking force amplification device to not operate properly, resulting in a dangerous situation. There is a problem with that.

The purpose of this invention is to solve the problems of the prior art described above.The present invention connects a brake booster to a negative pressure generator through a brake side piping system, and also connects a diaphragm for automatic engine stop through an engine automatic stop side piping system. The automatic stopping device for a diesel engine is characterized in that an orifice is disposed in a conduit of the piping system on the automatic engine stopping side.

The present invention will be specifically explained below based on the embodiments shown in FIGS. 2 to 6.

The embodiment shown in FIGS. 2 and 3 employs a vacuum pump (preferably a vane pump) 3 driven by an engine 2 as the negative pressure generating device 1. This vacuum pump 3 and the brake booster 4 of the vacuum braking force amplification device
and are connected by the brake-side piping system 5, and the two are in communication. A metal pipe or a strong rubber hose is used as a conduit for this brake side piping system 5. On the other hand, a vacuum pump 3 and a diaphragm device 6 for automatic engine stop
and is connected by an engine automatic stop side piping system 7. A three-way solenoid valve 8 is disposed in the middle of this piping system 7. Reference numeral 9 denotes a fuel injection pump, and an operating rod 11 of the diaphragm device 6 is connected to one end of an operating lever 10 for operating a fuel cutoff valve (not shown) provided in a fuel passage of the pump 9. The operating lever 10 is biased by a return spring 12 in the opening direction Q of the fuel cutoff valve. The three-way solenoid valve 8 is electrically connected to the ON position contact 13a of the key switch 13, and when the key switch 13 is turned ON, the negative pressure chamber 6a of the diaphragm device 6 is opened to the atmosphere through the atmosphere release pipe 14, while the key switch 13 is turned off, the negative pressure chamber 6a is configured to communicate with the vacuum pump 3.

Thus, when the key switch 13 is turned OFF when stopping the engine 2, the three-way solenoid valve 8
operates to communicate the negative pressure chamber 6a of the diaphragm device 6 with the vacuum pump 3,
The air in the negative pressure chamber 6a is sucked by the vacuum pump 3, and the operating rod 11 moves in the direction P in FIG. Close the isolation valve and
The fuel supply to the engine 2 is stopped and the engine 2 is stopped. On the other hand, turn key switch 13
When turned on, the three-way solenoid valve 8 opens the negative pressure chamber 6a of the diaphragm device 6 to the atmosphere and operates to block the flow path between the negative pressure chamber 6a and the vacuum pump 3, so that the return spring 12 Due to the restoring force, the operating lever 11 moves as shown in Fig. 2Q.
direction, the fuel cutoff valve opens, and fuel can be supplied to the engine 2.

Inside the vacuum pump 3, a one-way valve 15 is arranged as shown in FIG. 3, and a connecting fitting 16 is attached. A conduit 5a of the brake-side piping system 5 is connected to this connection fitting 16, and a connecting metal pipe 7a of the engine automatic stop-side piping system 7 is connected to the connection fitting 16. There is an orifice 1 in the conduit of this connecting metal pipe 7a.
7 is provided.

The diameter of the orifice 17 is such that the pressure inside the brake booster 4 can be maintained at a negative pressure state with a higher degree of vacuum than -300 mmHg even if the engine automatic stop side piping system 7 is damaged (rubber hose falling off, rubber hose broken, etc.). In addition, it is preferable to set it in a range such that the time required until the fuel is cut to the engine 2 by the operation of the three-way solenoid valve 8 under normal conditions is 1 second or less, and it is generally preferable to select it in the range of 0.5 mm to 1.2 mm.

In this embodiment, the engine automatic stop side piping system 7 includes the connecting metal pipe 7a, a rubber hose conduit 7b connecting the pipe 7 and the three-way solenoid valve 8, and a rubber hose conduit 7b connecting the three-way solenoid valve 8 and the diaphragm device 6. Although the orifice 17 is arranged within the connecting metal pipe 7a, the arrangement position of the orifice 17 is of course not limited to that of this embodiment. Further, as shown in FIG. 4, the orifice 17 can be integrally formed in the conduit portion of the engine automatic stop side piping system 7 of the connecting fitting 16a attached to the vacuum pump 3. In FIG. 3, 18, 18, . . . are vanes, 19 is a discharge port, and 20 is a connecting pipe for communicating the discharge port 19 with the crank chamber of the engine 2.

FIG. 5 shows the pressure in the brake side piping system 5 when the vacuum pump 3 is operated using the connection fitting 16a shown in FIG. 4 (the measurement point is set at point B in FIG. 4). It shows change. are normal, ,, are when the engine automatic stop side piping system 7 is open to the atmosphere, and when the orifice 17 has a diameter of 0.5 mm, 1.0 mm, and 1.2 mm, are the engine automatic stop side. It shows the pressure change when the piping system 7 is open to the atmosphere and does not have the orifice 17. The vacuum pump 3 used had a theoretical discharge rate of 28 CC/rev and a maximum allowable rotation speed of 10,000 rpm.

As is clear from FIG. 5, when the engine automatic stop side piping system 7 is normal, the pressure in the brake side piping system 5 drops to approximately -750 mmHg, but if the engine automatic stop side piping system 7 is damaged and When the orifice 17 is not provided, almost no pressure drop is observed. If the diameter of orifice 17 is 0.5mm, 1.0mm, 1.2mm,...
Since the pressures are reduced to about -650 mmHg, -480 mmHg, and -380 mmHg, respectively, a degree of vacuum higher than -300 mHg required for normal operation of the vacuum brake amplifier can be obtained.

FIG. 6 shows the pressure change in the engine automatic stop piping system 7 when the vacuum pump 3 is operated using the orifice 17 (point A in FIG. 4 is the measurement point). (The diameter of the diaphragm device 6 is 71.6 mm, and the spring constant of the return spring 12 is 53 g/mm.). As is clear from this figure, when the diameter of the orifice 17 is 0.5 mm, the -200 mmHg required to operate the diaphragm device 6 is reached in about 1 second. Orifice 17
Needless to say, when the diameter of the tube is set to 1.0 mm and 1.2 mm, the temperature reaches -200 mmHg in an even shorter time. In this way, adjust the diameter of orifice 17.
When it is larger than 0.5 mm, the response time of the diaphragm device 6 can be made 1 second or less, and there is no practical problem.

The present invention can be configured in various ways other than those shown in the above embodiments. For example, the negative pressure generator 1
Alternatively, one that utilizes the negative pressure in the intake pipe of the engine 2 may be adopted. Further, in the above embodiment, the fuel supply to the engine 2 can be cut off by the operation of the diaphragm device 6;
The configuration may be such that intake air supply to the engine 2 can be cut off.

As mentioned above, in this invention, an orifice is placed in the conduit of the engine automatic stop piping system, so there is no chance that the rubber hose will come off or break and the piping system on the engine automatic stop side will be directly exposed to the atmosphere. However, as long as this opening is located closer to the diaphragm device than the orifice, the vacuum level of the vacuum pump can be maintained at a predetermined value or higher due to the action of the orifice, and as a result, the vacuum brake amplifier device can operate normally. Operation can be ensured and safety can be improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the principle of the prior art, Fig. 2 is a schematic diagram showing the principle of the embodiment of the present invention, Fig. 3 is a longitudinal sectional view of the main part thereof, and Fig. 4 is a schematic diagram showing the principle of the embodiment of the present invention. The vertical sectional view of the main part of the embodiment, and FIGS. 5 and 6 are explanatory diagrams showing the action of the orifice of the present invention in a graph. 1... Negative pressure generator, 4... Vacuum pump, 5... Brake side piping system, 6... Diaphragm device, 7... Engine automatic stop side piping system, 17
...Orifice chair.

Claims (1)

[Scope of utility model registration request] A brake booster is connected to the negative pressure generating device via a brake side piping system, and a diaphragm device for automatic engine stop is connected via an engine automatic stop side piping system, in which the engine automatic stop side piping system is connected to a brake booster. An automatic stop device for diesel engines characterized by an orifice placed in the conduit.