JPH0921407A - Torque transmission mechanism and fuel injection device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regulate a phase between a rotary shaft and a rotary member while preventing turning movement of a woodruff key in a woodruff key groove by forming the woodruff key so as to steppedly displace a chord part to one side of a woodruff part, in a device formed in such a constitution that a torque is given and received between the rotary shaft and the rotary member using the woodruff key. SOLUTION: A woodruff key 1 is provided with a woodruff part 1a whose circumferential surface is formed in a circular arc surface shape, and a straight chord part 1b formed continuously to the woodruff part 1a. In this case, the chord part 1b is formed to have a difference in level by displacing in a prescribed dimension on one side of the woodruff part 1a. The woodruff key 1 is installed between a rotary shaft 10 and a rotary member (a gear) 20. Namely, a woodruff groove 11 is formed along an axial direction on the rotary shaft 10, a straight key groove 22 is formed along the axial direction on the installing hole 21 inner surface of the gear 20, the woodruff part 1a of the woodruff key l is dropped down on the woodruff groove 11 of the rotary shaft 10, and chord part 1b of the woodruff key 1 is fit to the key groove 22 of the gear 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque transmission mechanism that transmits and receives torque between a rotary shaft and a rotary member by using a half-moon key and a fuel injection device using the same.

[0002]

2. Description of the Related Art A half-moon key is used as a mechanism for transmitting torque between a rotary shaft and a gear, a rotary shaft and a belt wheel, a rotary shaft and a shaft coupling, and the like. The torque transmission mechanism using this kind of half-moon key forms a half-moon groove on the side surface of the rotary shaft, and the lower half-moon part of the half-moon key is fitted into this half-moon groove, and the upper chord part protruding from this half-moon groove is attached to the rotary shaft. It is fitted in a key groove formed on the inner surface of the counterpart rotary member covered with the above, and torque of either one of the rotary shaft and the rotary member is transmitted to the other through the half-moon key.

[0003]

By the way, in this type of half-moon key, when the half-moon is fitted in the half-moon groove, the upper surface of the upper chord part is in a posture parallel to the side surface of the rotating shaft. desirable. However, in general, the fitting of the half-moon key and the half-moon groove is often a clearance fit in consideration of easiness of attachment and detachment work at the time of assembling and disassembling the rotary shaft and the rotary member. For this reason, when the rotary shaft is fitted into the hole of the rotary member, the rotary member may come into contact with the half-moon key and the half-moon key may rotate in the half-moon groove, causing a positional deviation such as tilting. There is a problem that the half-moon key falls out of the half-moon groove. Therefore, a measure for preventing the half-moon key from rotating in the half-moon groove is desired.

On the other hand, in the torque transmission mechanism using the half-moon key, the half-moon portion of the half-moon key fits into the half-moon groove on the rotary shaft side and the chord portion fits into the key groove of the rotary member. The members are rotationally positioned. Therefore, when it is desired to change the rotational phases of the rotary shaft and the rotary member, there is a problem in that they cannot be dealt with.

A typical example of the use of this type of torque transmission mechanism using a half-moon key is an engine fuel injection device. The fuel injection device of the engine injects the fuel supplied from the fuel injection pump into the combustion chamber of the engine through the injection nozzle. The fuel injection timing needs to be adjusted according to the engine speed. Therefore, a fuel injection timing adjusting device, that is, an automatic timer is used. In the above timer, a centrifugal weight is housed in a timer housing rotated by an engine, and the eccentric cam adjusts the phase of the centrifugal weight in accordance with the rotation speed of the timer housing. The rotation is transmitted to the timer hub. Therefore, by connecting the timer hub and the cam shaft of the fuel injection pump, the rotation whose phase is adjusted by the automatic timer is transmitted to the fuel injection pump, which causes the fuel injection pump to have a predetermined timing according to the number of rotations. It is designed to send out fuel.

In such a fuel injection device, the above-mentioned torque transmission mechanism using the half-moon key is used to connect the cam shaft of the fuel injection pump and the timer hub of the automatic timer. That is, a half-moon groove is formed on the cam shaft, a half-moon portion of the half-moon key is fitted into the half-moon groove, and a key groove is formed on the inner surface of the timer hub. It is fitted and transmits the rotation of the timer hub to the cam shaft via the half-moon key.

In the fuel injection device having such a structure, since the rotation whose phase is adjusted by the automatic timer is transmitted to the fuel injection pump, the rotation phase must be determined with high accuracy.

However, machining errors and assembly errors occur in the respective components of the timer as described above, such as the centrifugal weight and the eccentric cam, and such errors are accumulated in the connecting portion between the timer hub and the cam shaft. Expanded. The error magnified in this way is transmitted to the fuel injection pump, causing variations in the injection timing.

Therefore, such an error must be eliminated as much as possible. In the conventional case, the processing accuracy of each component of the timer is increased, the assembly accuracy is improved,
In addition, the specified mounting accuracy is achieved by making fine adjustments, etc., but it requires a great deal of labor to correct these,
And there are limits. In addition, there is a problem that the engine cannot be mounted or the performance is deteriorated, although a lot of labor is spent.

Therefore, an object of the present invention is to provide a torque transmission mechanism which does not rotate the half-moon key in the half-moon groove, and which can adjust the phase between the rotary shaft and the rotary member, and the torque transmission mechanism. The present invention aims to provide the fuel injection device.

[0011]

[Means for Solving the Problems]

[Structure] In order to achieve the above object, the invention of claim 1 has a rotary shaft having a half-moon groove formed on its side surface; a hole into which the rotary shaft is inserted; A half-moon key having a half-moon portion and a string portion connected to the half-moon portion, the half-moon portion being attached to the half-moon groove and the string portion being fitted in the key groove; Is a torque transmission mechanism in which the string portion is offset to one side of the half-moon portion in a step shape.

According to the invention of claim 2, the fuel injection timing is such that the cam shaft of the fuel injection pump having a half-moon groove formed on the side surface and the key groove having the chord part of the half-moon key formed on the inner surface thereof are formed. A timer hub of the adjusting device; a half-moon key having a half-moon portion and a string portion connected to the half-moon portion, the half-moon portion being attached to the half-moon groove and the string portion being fitted into the key groove; The fuel injection device is characterized in that the chord portion is offset to one side of the half-moon portion in a step shape.

[Operation] According to the invention of claim 1, since the chord portion of the half-moon key is offset to one side of the half-moon portion in a step shape, when the half-moon portion is fitted into the half-moon groove, the chord portion is inserted. Rides on the side surface of the rotating shaft corresponding to the opening surface of the half-moon groove, and thus the half-moon key is prevented from rotating.

Further, since the chord portion is deviated to one side of the half-moon portion, it is possible to shift the rotational phases of the rotating shaft and the rotating member by an amount corresponding to this deviation amount. Also, when the half-moon key is installed by reversing the right and left, the deflection direction of the string portion becomes the opposite position, so that the rotational phase can be shifted in this direction.
Therefore, the rotation phase can be adjusted.

According to the second aspect of the present invention, the same operation as that of the first aspect is achieved, and therefore, the variation of the rotational phase transmitted from the timer to the fuel injection pump is provided between the timer hub and the cam shaft. It can be corrected with the key, and the variation in the injection timing can be suppressed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the first embodiment shown in FIGS. The present embodiment shows an example in which an example of a torque transmission mechanism using a half-moon key is applied to a connecting portion of a rotary shaft and a gear, FIG. 1 is a diagram showing a configuration of the half-moon key, and FIG. FIG. 3 is a diagram showing a connecting structure of the rotating shaft and the gear.

FIG. 1A is a perspective view showing the whole half-moon key, FIG. 1B is a side view, and FIG. 1C is a front view. The illustrated half-moon key 1 is composed of a half-moon part 1a whose circumferential surface is formed into an arc surface and a straight chord part 1b formed continuously with the half-moon part 1a, and the chord part 1b is the half-moon part. The step 1a is formed in a step shape with a predetermined size deviation on one side.

The half-moon key 1 as described above is mounted between the rotary shaft 10 and the gear 20 corresponding to the rotary member of the present invention, as shown in FIG. That is, as shown in FIG. 2A, a half-moon groove 11 is formed on the side surface of the rotary shaft 10 along the axial direction. Further, a straight key groove 22 along the axial direction is formed on the inner surface of the mounting hole 21 of the gear 20.
Are formed.

The half-moon groove 1 of the half-moon key 1 is inserted into the half-moon groove 11 of the rotary shaft 10, and the chord portion 1b of the half-moon key 1 is fitted in the key groove 22 of the gear 20.
Since the string portion 1b of the half-moon key 1 is displaced from the half-moon portion 1a, the half-moon groove 11 of the rotary shaft 10 and the key groove 22 of the gear 20 are circumferentially displaced, that is, corresponding to this displacement amount. The rotational phases are out of phase, and the rotating shaft 10 and the gear 20 are coupled in this state.

With the half-moon key 1 having such a structure, when the half-moon portion 1a of the half-moon key 1 is mounted on the half-moon groove 11 of the rotary shaft 10, even if these are fitted by a clearance fit, the half-moon groove 11 is formed. Since the string portion 1b protruding from the half-moon portion 1a is offset to one side, as can be understood from FIG. 2B,
The chord portion 1b rides on the side surface of the rotating shaft 10 corresponding to the opening surface of the meniscus groove 11. Therefore, half-moon key 1 is half-moon groove 1
Rotation along 1 is prevented. Therefore, the rotating shaft 1
If the mounting hole 21 of the gear 20 is fitted into the
Even if the inner surface or the keyway 22 contacts the half-moon key 1, the half-moon key 1
The inclination and dropout of are prevented.

As a result, the work of attaching and detaching the gear 20 is facilitated, the work efficiency is improved, and since the half-moon key 1 receives the torque on the wide side surface, a large torque can be transmitted.

Further, since the chord portion 1b is deviated from the half-moon portion 1a, the half-moon groove 11 of the rotary shaft 10 and the key groove 22 of the gear 20 are coupled by being displaced in the circumferential direction. Therefore, the rotational phases of the rotary shaft 10 and the gear 20 can be shifted. That is, to explain in detail with reference to FIG. 3, the connection structure shown in FIG. 3 (A) shows the case where the conventional half-moon key 30 is used, and the conventional half-moon key 30 has the half-moon portion and the chord portion deviated. Since there is not, the half moon groove 11 of the rotary shaft 10 and the gear 20
The key grooves 22 of are aligned in the circumferential position. In this case, the angle between the reference point a of the gear 20 and the position of the meniscus groove 11 formed on the rotary shaft 10 is θ ₀ .

On the other hand, as shown in FIG.
When the half-moon key 1 of this example is used, the half-moon part 1a and the chord part 1b are deviated, so that the half-moon groove 11 of the rotary shaft 10 and the gear 20 are rotated.
The key groove 22 of is shifted in the circumferential direction, and the angle between the reference point a of the gear 20 and the position of the meniscus groove 11 formed on the rotating shaft 10 is θ _1.
Therefore, compared with the case of FIG. 3A, θ ₁ −θ ₀ = α
The phase changes by minutes.

On the other hand, when the half-moon key 1 of this example is used by reversing the horizontal direction as shown in FIG. 3C, the half-moon portion 1a and the chord portion 1b are used.
Are deviated in the opposite direction, and the half-moon groove 11 of the rotary shaft 10 and the gear 20
The key groove 22 of is displaced in the opposite circumferential direction. In this case, the angle between the reference point a of the gear 20 and the position of the meniscus groove 11 formed on the rotary shaft 10 is θ ₂ , which is θ ₀ −θ ₂ = α, as compared with the case of FIG. The phase changes in the opposite direction.

Therefore, if the half-moon key 1 of this example is used, the rotational phases of the rotary shaft 10 and the gear 20 can be adjusted. In addition, according to the present invention, the half-moon groove 11 of the rotary shaft 10 and the key groove 22 of the gear 20 do not need to be changed from the conventional structure.
The conventional half-moon key 30 can also be used as shown in FIG.

Next, an example in which the torque transmission mechanism of the present invention is applied to a fuel injection device for an engine will be described with reference to FIGS. 4 to 7. FIG. 4 shows the overall structure of the fuel injection device,
Reference numeral 100 is a fuel injection pump, 200 is a fuel injection timing adjusting device, that is, an automatic timer, and 300 is a governor.

The fuel injection pump 100 is a column-type fuel injection pump, and has a fuel pressurizing mechanism consisting of cams and plungers of the same number as the number of cylinders of the engine (not shown), and each cam moves the plunger up and down. The fuel pressurizing mechanisms are arranged in series so as to operate in the order of combustion of the cylinders. Each cam is operated by a cam shaft 220, which will be described later, which is led to one side.

The fuel injection pump 100 has a structure in which the fuel sucked up from the fuel tank by the feed pump 110 provided on the lower side surface of the main body of the fuel injection pump 100 is
The fuel is pressurized by the fuel pressurizing mechanism including the cam and the plunger, and the high-pressure fuel is sent to the injection pipe (not shown) through the delivery valve 120 provided at the upper part of the main body of the fuel injection pump 100, and is supplied to the injection nozzle from the injection pipe. It is designed to be injected into the combustion chamber.

As will be described later, the automatic timer 200 automatically adjusts the phase between the engine and the injection pump 100 so that the fuel injection timing becomes optimum with respect to the crank angle of the engine according to the engine speed and the magnitude of the load. To adjust to.

The governor 300 operates a control rack (not shown) of the fuel injection pump 100 according to the change of the load to automatically adjust the fuel supply amount, and is well known.

The automatic timer 200 will be described with reference to FIGS. In the figure, reference numeral 201 denotes a timer housing, which has a tubular shape having an end wall 202 at one end. On this end wall 202, the timer gear 2
03 is fixed via a connecting bolt 204, and this timer gear 203 meshes with a drive gear connected to a crankshaft of an engine (not shown). Therefore, the timer housing 201 is rotated in synchronization with the engine.

Reference numeral 205 denotes a timer hub, which is provided with a flange portion 206 on the outer circumference. The flange portion 206 is slidably fitted inside the peripheral wall of the timer housing 201, and is in sliding contact with the end wall 202. Therefore, the timer housing 201 and the timer hub 205 can be rotationally displaced relative to each other.

The other end opening of the timer housing 201 is closed by an end plate 207 screwed into this opening. The end wall 20 of the timer housing 201
7, an oil seal 208 is provided between the timer hub 205, and another oil seal 209 is also provided between the end plate 207 and the timer hub 205. Then, the end plate 207 and the timer housing 2
An O-ring 210 is fitted between the open end of 01.

An eccentric cam mechanism is provided on the flange portion 206. The eccentric cam mechanism is configured as follows. That is, the first circular cams 215 and 215 are rotatably fitted to the flange portions 206 at eccentric and symmetrical positions. These first circular cams 21
Second circular cams 216, 216 are rotatably fitted in the eccentric positions in 5, 215, respectively.

Second pins 217 and 217 are fitted to the second circular cams 216 and 216 at eccentric positions,
One end of each of the second pins 217 and 217 is projected, and the projecting end is the end wall 20 of the timer housing 201.
2 is press-fitted.

Further, the first pins 218 and 218 are fitted to the eccentric positions of the first circular cams 215 and 215, and the protruding ends of these first pins 218 and 218 are attached to the centrifugal weights 220 and 220. It is press-fitted.

Therefore, the rotation of the timer housing 201 is transmitted to the second circular cams 216 and 216 via the second pins 217 and 117, and the first circular cam 21 is rotated.
Since the flange portion 206 is rotated through 5, 215, the timer hub 205 is rotated.
The rotation of 5 is transmitted to the cam shaft 150 of the fuel injection pump 100.

Inside the timer housing 201, a pair of centrifugal weights 220, 220 are arranged. The centrifugal weights 200, 200 surround the timer hub 205 and are displaced in the radial direction due to an increase in centrifugal force due to an increase in the number of rotations. In this case, the pair of centrifugal weights 220, 220 linearly move in a direction in which they approach and separate from each other while maintaining a substantially parallel state.

The first pins 218 and 218 connected to the eccentric positions of the first circular cams 215 and 215 are press-fitted into these centrifugal weights 220 and 220. When it is displaced in the radial direction due to the increase, this displacement causes the displacement of the first pins 218, 2
It is transmitted to the first circular cams 215 and 215 through 18. In this case, the first circular cams 215 and 215 rotate in the direction of arrow A shown in FIG. Second by this rotation
The circular cams 216 and 216 are rotated in the direction of arrow B. The rotation of the second circular cams 216 and 216 is transmitted to the timer housing 201 via the second pins 217 and 217, and as a result, the timer housing 201 and the flange portion 206 are relatively angularly displaced, and thus the timer housing 201. On the other hand, the phase of the timer hub 205 is changed to the advance side.

Guide rods 221 and 221 penetrate between the pair of centrifugal weights 220 and 220.
Retaining rings 222 and 222 are provided at both ends of each guide rod 221.
The end spring seats 223 and 223 are attached via the. The centrifugal weight 220 includes an inner spring seat 22.
4, 224 are in contact with each other, and the end spring seats 223, 223 are provided.
Coil springs 225 and 225 are stretched between the inner side spring seats 224 and 223 and the inner side spring seats 223. Therefore,
The rotation of the timer housing 201 causes the centrifugal weight 22 to rotate.
Centrifugal weight 220,2 when centrifugal force is generated in 0,220
20 is moved in the outer diameter direction while being guided by the guide rods 221 and 221 against the pressing force of the coil springs 225 and 225.

The cam shaft 150 of the fuel injection pump 100 is connected to the timer hub 205. That is, the conical hole 230 is formed at the end of the timer hub 205. A straight key groove 231 is formed on the inner surface of the conical hole 230. On the other hand, a conical tapered surface 151 is formed at the end of the cam shaft 150 of the fuel injection pump 100, and a male screw portion 152 is formed at the tip of this. And this cam shaft 150
A half-moon groove 153 is formed on the tapered surface 151.

The half-moon key 1 of the present invention is attached between the half-moon groove 153 of the cam shaft 150 and the key groove 231 of the timer hub 205. As shown in FIG. 1, the half-moon key 1 has a half-moon portion 1a and a string portion 1b that is offset in a step shape,
The half-moon portion 1 a is fitted in the half-moon groove 153 of the cam shaft 150, and the chord portion 1 b is fitted in the key groove 231 of the timer hub 205.

Further, the male screw portion 152 formed at the tip of the cam shaft 150 is inserted into the timer hub 205, and the round nut 240 fitted from the other end of the timer hub 205 is screwed into the male screw portion 152. ing. The cam shaft 150 and the timer hub 205 are axially coupled by the round nut 240.

In the fuel injection device having such a structure, the rotation is transmitted to the cam shaft 150 of the fuel injection pump 100 through the half-moon key 1 to the timer hub 205 on the timer 200 side, and the half-moon key 1 is stepped with the half-moon portion 1a. Since the half-moon portion 1a is fitted into the half-moon groove 153 of the cam shaft 150 and the chord portion 1b is fitted into the key groove 231 of the timer hub 205, the chord portion 1b is deviated to the first embodiment. Has the same effect.

That is, when the half-moon portion 1a of the half-moon key 1 is mounted in the half-moon groove 153 of the cam shaft 150, the chord portion 1b abuts the outer surface of the cam shaft 150 and the rotation thereof is blocked. Therefore, even when the inner surface of the conical hole 230 or the key groove 231 contacts the half-moon key 1 when the timer hub 205 is covered with the cam shaft 150, the half-moon key 1 is prevented from being inclined or falling off. Therefore, the work of attaching / detaching the timer hub 205 and the cam shaft 150 is facilitated, the work efficiency is improved, and since the half-moon key 1 receives the torque on the wide side surface, a large torque can be transmitted.

Moreover, since the chord portion 1b is offset from the half-moon portion 1a, the half-moon groove 153 of the cam shaft 150 and the key groove 231 of the timer hub 205 are coupled so as to be displaced in the circumferential direction.
Therefore, the rotation phases of the timer hub 205 and the cam shaft 150 can be shifted. This phase shift corresponds to the amount of deviation of the string portion 1b, and the case shown in FIG. 3B or the case shown in FIG. 3C can be selected.

For this reason, processing errors and assembly errors occur in each component of the timer 200, such as the centrifugal weight 220 and the eccentric cams 215 and 216, and such errors occur in the connecting portion between the timer hub 205 and the cam shaft 150. Even if they are accumulated and enlarged, the enlarged error can be absorbed by selecting and using the mounting posture of the half-moon key 1. Therefore, the rotation of which the phase is adjusted by the timer 200 is transmitted to the fuel injection pump 100, the operation of the fuel injection pump 100 can be made highly accurate, and the variation in the fuel injection timing can be prevented.

When it is not necessary to adjust the phase between the timer hub 205 and the cam shaft 150, the above-mentioned FIG.
The conventional half-moon key 30 can also be used as shown in FIG.

[0049]

As described above, according to the invention of claim 1, since the half-moon key is composed of the half-moon part and the chord part which is offset to one side stepwise, the half-moon part is the half-moon part. The rotation of the half-moon key is prevented when the half-moon key is fitted in the groove, and the half-moon key is prevented from tilting or falling off even if the half-moon key comes into contact with the half-moon key. Therefore, the work of attaching and detaching the rotary shaft and the rotary member is facilitated, and the work efficiency is improved.

Further, since the string portion is deviated to one side of the half-moon portion, the rotation phase of the rotary shaft and the rotary member can be shifted by an amount corresponding to this deviation amount, and the half-moon key can be pressed. If it is installed by reversing the right and left, the deflection direction of the chord portion becomes opposite, so that the rotational phase can be shifted also in this direction. Therefore, the rotation phase can be adjusted.

Further, according to the invention of claim 2, since the half-moon key similar to that of claim 1 is mounted between the timer hub of the timer and the cam shaft, the same operation as that of claim 1 is achieved.
Therefore, the phase variation between the timer and the fuel injection pump, which is highly required to prevent the phase error, can be adjusted with high accuracy, and the variation in the injection timing can be suppressed.

[Brief description of drawings]

1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is a perspective view showing the whole half-moon key, FIG. 1B is a side view, and FIG. 1C is a front view.

2A and 2B show details of a mounting state of the half-moon key of the embodiment, FIG. 2A is a sectional view, and FIG. 2B is a sectional view taken along line IIB-IIB.

3A and 3B show an example in which the half-moon key according to the related art and the present embodiment is used in a connecting portion between a rotary shaft and a gear. FIG. 3A is a diagram when a conventional half-moon key is used, and FIG. The figure when the half-moon key of the implementation is used, and the figure (C) is the figure when the half-month key of this implementation is used in reverse.

FIG. 4 is a side view showing the second embodiment of the present invention and showing the entire fuel injection device.

FIG. 5 is a sectional view of the automatic timer of the same embodiment.

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is an exploded perspective view of the timer hub and the cam shaft of the embodiment.

[Explanation of symbols]

 1 ... Half moon key 1a ... Half moon part 1b ... Chord part 10 ... Rotating shaft 11 ... Half moon groove 20 ... Gear (rotating member) 21 ... Mounting hole 22 ... Key groove 100 ... Fuel injection pump 150 ... Camshaft 151 ... Tapered surface 153 ... Half-moon groove 200 ... Automatic timer 300 ... Governor 201 ... Timer housing 203 ... Timer gear 205 ... Timer hub 206 ... Flange portion 215 ... First circular cam 216 ... Second circular cam 217 ... Second pin 218 ... First pin 220 … Centrifugal weight 225… Coil spring 230… Conical hole 231… Key groove 240… Round nut

Claims (2)

[Claims] 1. A rotary shaft having a half-moon groove formed on its side surface; a rotary member having a hole into which the rotary shaft is inserted, and a key groove formed on the inner surface of the hole; A half-moon key that is attached to the half-moon groove, and the half-moon part is fitted into the key groove, and the half-moon key is one of the half-moon part. A torque transmission mechanism, which is laterally offset in a step shape. 2. A camshaft of a fuel injection pump having a half-moon groove formed on a side surface thereof, and a timer hub of a fuel injection timing adjusting device having an inner surface provided with a key groove for locking the chord portion of the half-moon key; A half-moon key having a string part and a string part connected to the half-moon part, the half-moon part being mounted in the half-moon groove and the string part being fitted in the key groove; A fuel injection device, wherein the fuel injection device is offset to one side of the portion in a stepped shape.