JPH02191827A - Prestroke control mechanism for fuel injecting device - Google Patents

Abstract

PURPOSE:To advance the fuel injecting period a the time of starting at low temperature by forming an actuator for turning a timing rod with a wound spring made of the form storage alloy and an ordinary wound spring and a lever. CONSTITUTION:An actuator for turning a timing rod 26 consists of a wound spring 50 made of the form storage alloy and an ordinary wound spring 51 and a lever 52, and one end of the lever 52 is fixed on one end of the timing rod 26, and a pin 53 is standingly provided on the other end of the lever. Each one end of both wound springs 50, 51 is respectively connected to the pin 53, and other ends are respectively connected to a pump housing 2. The timing rod 26 is turned to the direction to lower the timing sleeve at low temperature by vertically locating both wound springs 50, 51 along the axial direction of a plunger. Thereby, the reduction of the prestroke at low temperature is facilitated. Further, the actuator itself can sense the temperature and operate automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a prestroke control mechanism for a fuel injection device.

(Prior Art) The prestroke control mechanism of a conventional fuel injection device includes a timing sleeve that adjusts the prestroke position, a timing rod that moves the timing sleeve up and down along a plunger, and an electromagnetic system that rotates the timing rod. It is equipped with an actuator.

When the timing rod is rotated by the electromagnetic actuator, the timing sleeve moves up and down along the plunger. As a result, the prestroke position changes.

(Problems to be Solved by the Invention) However, in the case of a fuel injection device using an electromagnetic actuator, the structure is complicated and a control unit is required, so the manufacturing cost is higher than that of a mechanical fuel injection device. Furthermore, during low-temperature starting, the sliding resistance is large and the battery voltage is low, making it difficult to lower the timing sleeve to reduce the prestroke.

Book-1! The invention was developed in view of the above-mentioned circumstances, and the purpose is to provide a pre-stroke control mechanism for a fuel injection device that can advance the fuel injection timing during cold start and reduce manufacturing costs. do.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a timing sleeve for adjusting a pre-stroke position that is slidably attached to a plunger, and a timing for moving the timing sleeve up and down along the plunger. A rod is rotatably attached to the plunger in a direction perpendicular to the plunger, and a tip of a pin fixed to the timing rod is slidably fitted into a groove in the timing sleeve, so that the timing rod is In the pre-stroke control mechanism of a fuel injection device equipped with a rotating actuator,
The actuator is composed of a shape memory alloy coil spring, a normal coil spring, and a lever, one end of the lever is fixed to one end of the timing rod, and a pin is erected at the other end of the lever. One end of each of the coil springs is connected to a pin of the lever, the other end of each of the coil springs is connected to a pump housing, and the two coil springs are connected along the axial direction of the plunger. By arranging the timing rods in tandem, the timing rods are rotated in the direction of lowering the timing sleeve at low temperatures.

The actuator includes a wax whose volume changes significantly due to temperature changes, a shaft fixed to the wax, and a timing rod that controls the movement of the shaft that moves along the axial direction of the plunger in response to the wax. S may also be composed of a lever that converts the rotational movement of the

(Function) The actuator consists of a shape memory alloy coil spring, a normal coil spring, and a lever, one end of the lever is fixed to one end of the timing rod, and a pin stands at the other end of the lever. one end of each of the coil springs is connected to a pin of the lever, the other end of each of the coil springs is connected to a pump housing, and the two coil springs are connected in a direction 111 of the plunger. By arranging the timing rods in tandem along the axis, the timing rods are rotated in the direction of lowering the timing sleeve at low temperatures, making it easy to reduce the prestroke at low temperatures. Furthermore, since the actuator itself senses the temperature and operates automatically, a control unit for controlling the actuator is not required.

Further, the actuator includes a wax whose volume changes significantly due to temperature changes, a shaft fixed to the wax, and a shaft that moves along the axial direction of the plunger in response to the wax (movement of the shaft is controlled by the timing). The lever converts the movement into rotational movement of the rod, so when the temperature is low, the wax contracts and the shaft lowers, and the lever converts the downward movement of the shaft into rotational movement of the timing rod, lowering the timing sleeve, and reducing the prestroke. In this way, the actuator operates independently of the battery voltage, so the prestroke can be easily reduced at low temperatures.Also, since the actuator itself senses the temperature and operates automatically, it is easy to control the actuator. No control unit is required.

(Example) An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a front view showing a prestroke control mechanism of a fuel injection device according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing a fuel injection device equipped with the prestroke control mechanism.

In the figure, 2 is a housing of a diesel engine-shaped fuel injection device, 4 is one of a plurality of barrels held within the housing, and the axis of each barrel 4 is aligned with the housing 2.
They are arranged in parallel on one side of the interior. 6 is a discharge valve holder attached to the upper part of each barrel 4 and connected to each cylinder of the engine, 7a is a discharge valve, 8 is a plunger slidably fitted in each barrel 4, and 10 is the plunger. 12 is a cam that is linked to the drive shaft of an engine (not shown) and pushes up the plunger 8; 14 is a timing sleeve slidably fitted around the outer periphery of the plunger 8; 16 is fixed to each barrel 4; A guide pin 18 that engages with the guide groove I7 of the timing sleeve 14 to restrict its rotation is a sleeve rotatably supported by the barrel 4 and non-rotatably engaged with the plunger 8. The plunger 8 has an oil passage 8a that communicates between the upper end surface and the circumferential side, a circumferential side opening 8b that communicates with the oil passage 8a and is formed on the circumferential side, and a vertical groove 8C that extends along the plunger axis.
and an inclined groove 8d that is inclined with respect to the plunger axis, and a control groove is formed by the grooves 8c and 8d and the peripheral side opening 8b (hereinafter referred to as opening). On the other hand, the timing sleeve 14 is provided with a control hole 14a that defines an injection path.

Reference numeral 15 indicates a fuel chamber that stores fuel supplied from a feed pump (not shown), and the fuel is stored in the barrel 4 because the plunger 8 is fitted into the barrel 4 in an oil-tight state.
No leakage into the camshaft chamber 13.

Further, reference numeral 21 indicates an oil supply port for supplying lubricating oil into the camshaft chamber 13, and 23 indicates a guide pin protruding from the tappet 25, which is slidably engaged with a guide groove 27 carved in the housing 2. do. Reference numeral 29 is a pre-stroke fine adjustment adjustment screw screwed into a threaded hole of a timing rod 26, which will be described later.By loosening the screw and appropriately rotating the pin 28, the pre-stroke of the plunger 8 is finely adjusted. It is something that can be done.

The actuator for rotating the timing rod 26 includes a shape memory alloy coil spring 50, a normal coil spring 51, and a lever 52, as shown in FIG. One end of the lever 52 is fixed to one end of the timing rod 26, and a pin 53 is fixed to the other end of the lever 52.

One end of the coil springs 50, 51 is connected to a pin 53 of the lever 52, and the other end of the coil spring 50, 51 is connected to a pin 54, 55, respectively, provided upright on the outer wall surface of the housing 2. be. The coil springs 50, 51 are arranged in tandem along the axial direction of the plunger 8. In the case of this embodiment, a normal coiled spring 51 is arranged on the upper side, and a coiled spring 50 made of a shape memory alloy is arranged on the lower side, and the spring spring 50 made of a shape memory alloy is designed to contract at low temperatures. .

That is, since the coiled spring 50 tends to contract at low temperatures, the spring force of the coiled spring 50 made of shape memory alloy is greater than that of the normal coiled spring 51, and the lever 5
．． 2 is the timing rod 2 pulled by the cam 12 (11)
6 rotates counterclockwise, the timing sleeve 14 moves toward the small prestroke side, and the coiled spring 5 rotates at high temperatures.
0 tries to expand, the spring force of the normal coil spring 51 is greater than that of the shape memory alloy coil spring 50, the timing rod 26 rotates clockwise, and the timing sleeve 14 moves to the large side of the prestroke. is maintained.

Furthermore, in the above configuration, when the cam I2 rotates once, the roller 25a of the tappet 25 moves the plunger 8 upward by a portion every time the cam I2 rotates once due to the camshaft 12a interlocking with the rotational force received from the drive shaft of the engine. Lift amount, i.e. 1
It reciprocates up and down the stroke.

Here, the process of pumping fuel by the plunger 8 being pressed by the cam 12 will be explained with reference to FIGS. 14 is in the state shown in FIG. Not pumped. Next, the opening 8b passes through the state of (b) and then opens the timing sleeve 1 as shown in (C).
4 , the pressurizing chamber 20 is cut off from the fuel chamber 15 and pressurized by the plunger 8 . This (a)~
The stroke of the plunger 8 between (C) is called prestroke.

(C) When the plunger 8 rises as shown in the figure, the pressurizing chamber 2
The discharge pressure within 0 overcomes the spring force of the spring 7b of the discharge valve holder 6, the discharge valve 7a opens, and the high pressure fuel flows into the injection pipe 7a.
The water is supplied to an injection nozzle (not shown) via. Then, the inclined groove 8d of the plunger is inserted into the control hole 14a as shown in FIG.
However, when the inclined groove 8d comes to face the control hole 14a as shown in FIG. It communicates with chamber 15 and pressure feeding ends. Further, since the inclined groove 8d extends on the outer periphery of the plunger 8 at an angle with respect to its axis, by rotationally displacing the plunger 8 by the sleeve 18, the inclined groove 8d and the opening 14a of the control sleeve 14 are This allows you to change the response time of plunger 8.1.
The amount of injection per stroke can be adjusted. Note that the sleeve 18 is displaced in the rotational direction by displacing the rack 24, which engages with the ball 22 fixed on the sleeve 18, in its longitudinal direction.

The injection timing is controlled by slidingly displacing the timing sleeve 14 along the plunger 8. This sliding displacement is caused by a timing rod 26 that is supported by the housing 2 and is located on the side of the timing sleeve 14 and has an axis on a straight line that is parallel to the plane in which the barrels 4 are arranged in parallel and perpendicular to the axis of the plunger 8. , a pin 28 fixed to the timing rod 26 and extending from the timing rod toward the plunger 8, and a timing sleeve 1.
4 and engages with the tip of the pin 28 to link the rotational displacement of the pin about the timing rod 26 and the sliding displacement of the timing sleeve 14] 4
b.

Note that the outer circumferential surface of the tip of the pin 28 has a curvature that constantly contacts the inner circumferential surface of the groove 14b to prevent play.

According to the above configuration of the present embodiment, the effective stroke of the plunger is changed by rotating the plunger 8 around its axis and changing the relative position of the control hole 14a with respect to the inclined groove 8d forming a part of the control groove. Therefore, the fuel injection amount can be adjusted.

Further, by rotationally displacing the timing rod 26 having the lever 28, the timing sleeve 14 is displaced in the axial direction of the plunger. As a result, the plunger's bristle stroke changes, allowing the injection timing to be adjusted.

FIG. 5 shows a prestroke control mechanism of a fuel injection device according to another embodiment of the present invention, and FIG. 5(a) is a front view thereof;
Figure (b) is a side view.

In the embodiment shown in FIG. 1, a case was described in which an actuator consisting of a shape memory alloy coiled spring 50, a normal coiled spring 51, and a lever 52 was used, but instead of this, the actuator shown in FIG. As shown in (b), a wax 60 that contracts at low temperatures and expands at high temperatures;
0, and a lever 62 that converts the movement of the shaft 61, which moves along the axial direction of the plunger 8 in response to the wax 60, into rotational movement of the timing rod 26. The same effect as in the embodiment shown in FIG. 1 can be obtained by housing this actuator in a cover 63 that stores fuel and operating the actuator according to the temperature of the fuel.

Incidentally, according to the actuators shown in FIGS. 5(a) and 5(b), as shown in FIG. 6, the prestroke increases as the temperature of the fuel increases.

(Effects of the Invention) As explained above, according to the prestroke control mechanism of the fuel injection device of the present invention, the actuator is composed of a shape memory alloy coil spring, a normal coil spring, and a lever, and one end of the lever is fixed to one end of the timing rod, a pin is erected at the other end of the lever, one end of each of the two coil springs is connected to a pin of the lever, and one end of each of the two coil springs is connected to a pin of the lever. The other ends are respectively connected to the pump housing, and by arranging both coiled springs in tandem along the axial direction of the plunger, the timing rod is rotated in the direction of lowering the timing sleeve at low temperatures. It is easy to reduce the prestroke at low temperatures, and since the actuator itself senses the temperature and operates automatically, there is no need for a control unit to control the actuator, and costs can be reduced.

Further, the actuator controls the movement of the wax whose volume changes significantly due to temperature changes, the shaft fixed to the wax, and the shaft that moves along the axial direction of the plunger in response to the front 3C wax at the timing. It consists of a lever that converts the rotational movement of the rod,
When the temperature is low, the wax contracts and the shaft lowers, and the lever converts the downward movement of the shaft into a rotational movement of the timing rod, lowering the timing sleeve and reducing the prestroke. Since the actuator operates independently of battery voltage, the prestroke can be easily reduced at low temperatures.Also, since the actuator itself senses the temperature and operates automatically, the control unit that controls the actuator is not necessary, and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a prestroke control device according to an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view showing a fuel injection device equipped with the prestroke control device, and FIG. 3 is the same as that shown in FIG. It is a diagram explaining the operation of the prestroke control device,
4(a) is a diagram showing the state at low temperature, FIG. 4(b) is a diagram showing the state at high temperature, and FIGS. 4(a) to 4(d) are for explaining the relationship between the plunger and the timing sleeve. , and FIG. 5 show a prestroke control device according to another embodiment of the present invention, in which FIG. 6(a) is a front view, FIG. 6(b) is a side view, and FIG. It is a graph showing temperature characteristics of a prestroke control device.

Claims (2)

[Claims] 1. A timing sleeve for adjusting a pre-stroke position is slidably attached to the plunger, a timing rod for moving the timing sleeve up and down along the plunger is rotatably attached in a direction perpendicular to the plunger, and In the prestroke control mechanism of a fuel injection device, the prestroke control mechanism of a fuel injection device is provided with an actuator for rotating the timing rod, the tip of a pin fixed to the timing rod being slidably fitted into a groove of the timing sleeve. The actuator consists of a shape memory alloy coil spring, a normal coil spring, and a lever, one end of the lever is fixed to one end of the timing rod, and a pin is erected at the other end of the lever. , one end of each of the coil springs is connected to a pin of the lever, the other end of each of the coil springs is connected to a pump housing, and the two coil springs are arranged in tandem along the axial direction of the plunger. 1. A pre-stroke control mechanism for a fuel injection device, wherein the timing rod is arranged so as to rotate the timing rod in a direction to lower the timing sleeve at low temperatures. 2. A timing sleeve for adjusting a pre-stroke position is slidably attached to the plunger, a timing rod for moving the timing sleeve up and down along the plunger is rotatably attached in a direction perpendicular to the plunger, and In the prestroke control mechanism of a fuel injection device, the prestroke control mechanism of a fuel injection device is provided with an actuator for rotating the timing rod, the tip of a pin fixed to the timing rod being slidably fitted into a groove of the timing sleeve. An actuator includes a wax whose volume changes significantly due to temperature changes, a shaft fixed to this wax, and a movement of the shaft that moves along the axial direction of the plunger in response to the wax, and a rotation of the timing rod. A prestroke control mechanism for a fuel injection device characterized by comprising a lever that converts motion into motion.