JPH0441232Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a fuel injection pump drive device that can optimally adjust the fuel injection timing for injecting fuel into a cylinder in a diesel engine.

In general, when considering fuel efficiency, vibration, knocking noise, etc., diesel engines have
It is desirable to set the fuel injection timing later than the standard injection timing at low engine speeds, and to increase it as the engine speed increases.

For this reason, fuel injection pump drive devices that inject fuel into the cylinders of conventional diesel engines are equipped with an auto-timer or helical spline, or use helical gears, which control the rotation of the engine. The fuel injection timing is changed according to the number of fuel injections.

However, with the former type of automatic timer, helical spline, helical gear, etc., the larger the fuel injection pump that injects fuel into the cylinder, the larger the device becomes, making it difficult to install due to size, weight, etc. It becomes difficult. In addition, other disadvantages include that the structure is quite complicated and must be large, and that it is expensive.

The purpose of this invention is to provide a fuel injection pump drive device that can arbitrarily adjust fuel injection timing, has a simple structure, and can be obtained at low cost.

This invention provides a fuel injection pump drive device that operates a fuel injection pump by rotating a pump drive shaft in the circumferential direction by an output shaft that operates in synchronization with the rotation of the crankshaft of a diesel engine.
A shape memory alloy element is installed between the output shaft and the pump drive shaft, and the degree of torsion in the circumferential direction changes depending on temperature conditions to change the phase of the output shaft and the pump drive shaft. The above object is achieved by adding a temperature control means for controlling the shape memory alloy element to a predetermined temperature in synchronization with the rotation speed of the diesel engine.

Hereinafter, embodiments of this invention will be described in detail with reference to the drawings.

Reference numeral 1 shown in FIG. 1 is a diesel engine, and this diesel engine 1 is provided with a timing gear 2 that rotates in synchronization with a crankshaft. On the other hand, reference numeral 3 designates a fuel injection pump, which injects fuel into the cylinders of the diesel engine 1 from the fuel injection pump 3 by rotating a pump drive shaft 4. The output shaft 5 and the pump drive shaft 4 to which power is transmitted from the timing gear 2 are configured to rotate in synchronization with each other by a shape memory alloy element 7 connected via a flexible plate 6. . Here, the flexible plate 6 functions to absorb misalignment between the output shaft 5 of the diesel engine 1 and the pump drive shaft 4 of the fuel injection pump 3.

In addition, the shape memory alloy element 7 changes the degree of twist depending on temperature conditions, thereby changing the phase between the output shaft 5 connected to the timing gear 2 and the pump drive shaft 4, as shown in FIG. At room temperature, the fuel injection timing of the fuel injection pump 3 relative to the rotational speed of the engine 1 is set later than the standard fuel injection timing,
It is becoming faster as the temperature rises.
In the vicinity of the shape memory alloy element 7, a temperature control means 8 such as an electric heater whose temperature rises in synchronization with the rotation speed of the engine 1 in a normal state is installed to control the shape memory alloy element 7 of the engine 1. It is designed to heat up to a temperature that corresponds to the increase in rotational speed.

Next, the operation of the apparatus configured as described above will be explained.

First, when the engine 1 is operated at idling and low speed, the fuel injection timing is later than the standard injection timing because the shape memory alloy element 7 is maintained at a temperature close to room temperature. Further, when the engine 1 is operated at high rotation speed, the shape memory alloy element 7 is heated by the temperature control means 8 such as an electric heater as the rotation speed increases. Then, the heated shape memory alloy element 7 twists the pump drive shaft side in the rotational direction to change the phase between the crankshaft of the engine 1 and the pump drive shaft 4, thereby advancing the fuel injection timing.

Although the temperature control means 8 is an electric heater, it is not limited to this, and a device having both heating and cooling means is more effective.
Furthermore, since the response of shape memory alloy elements to temperature changes is not that sensitive, this idea
It is unsuitable for engines such as automobiles that require rapid and frequent changes in rotation speed, and is not suitable for engines that do not require frequent changes in rotation speed, such as engines that are larger than the size where a commercially available auto-timer is used. , implemented in medium-sized engines for power generation.

As explained in detail above, according to this invention, the fuel injection pump drive operates the fuel injection pump by rotating the pump drive shaft in the circumferential direction using the output shaft that operates in synchronization with the rotation of the crankshaft of the diesel engine. In the device, a shape memory alloy element is installed between the output shaft and the pump drive shaft, and the shape memory alloy element changes the phase of the output shaft and the pump drive shaft by changing the degree of torsion in the circumferential direction depending on temperature conditions. Since the memory alloy element is equipped with a temperature control means that controls the shape memory alloy element to a predetermined temperature in synchronization with the diesel engine rotation speed, the structure is simple and inexpensive, and the temperature control means can be adjusted according to the engine rotation speed. Optimal fuel injection timing can be set.

Therefore, the combustion effect of the engine can be improved, and vibration, noise, knocking phenomenon,
This has advantages such as being able to improve start-up performance.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of this invention. Figure 1 is a schematic configuration diagram showing the fuel injection pump drive device according to this invention installed in a diesel engine, and Figure 2 shows its shape. FIG. 3 is a diagram showing the relationship between the temperature of a memory alloy element and fuel injection timing. 1... Diesel engine, 3... Fuel injection pump, 7... Shape memory alloy element, 8... Temperature control device.

Claims (1)

[Scope of utility model registration request] In a fuel injection pump drive device that operates the fuel injection pump 3 by rotating the pump drive shaft 4 in the circumferential direction by the output shaft 5 that operates in synchronization with the rotation of the crankshaft of the diesel engine 1, the output shaft 5
and the pump drive shaft 4, there is a shape memory alloy element 7 whose twist degree in the circumferential direction changes depending on the temperature condition to change the phase between the output shaft 5 and the pump drive shaft 4.
is attached to the shape memory alloy element 7, and a temperature control means 8 is attached to the shape memory alloy element 7 to control the shape memory alloy element 7 to a predetermined temperature in synchronization with the rotation speed of the diesel engine 1. Fuel injection pump drive device.