JP2503393B2 - Fuel injection pump injection amount control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a distributed fuel injection pump used in a diesel engine, and more particularly to an injection amount control device for improving startability in cold weather.

[Conventional technology and problems]

The injection amount characteristic of this type of fuel injection pump changes as a → b → c → d → e → f as the pump speed increases during normal operation, as shown by the solid line in FIG. However, during idle operation, it changes as a → b → g → h. However, since the injection amount (c → d) at the pump speeds N ₁ to N ₂ is relatively small at the cold start of the engine, it takes time until the engine completes the explosion at the cold start, which leads to the complete explosion. There is a risk of stopping without doing anything. In order to avoid this, increase the resilience of the idle spring, change the part of the characteristic curve from g → h to the broken line g ′ → h ′, and change the injection amount from the pump speed N ₁ to N ₂ ′. If it is increased, the injection amount increases as shown by the one-dot chain line c ′ → d ′ even in the normal operating range, so that the amount of smoke is increased and not only the fuel consumption is deteriorated but also the pollution is preferable. Absent.

Therefore, conventionally, the characteristic curve a → b → c ′ at the time of cold start.
A fuel injection pump that can obtain an injection amount along the line d → d → e → f and can also obtain an injection amount along the characteristic curve a → b → c → d → e → f during normal operation other than cold start Is desired. In Japanese Utility Model Laid-Open No. 59-76760, the magnitude of the elastic force of an idle spring (start idle spring) inserted between a control lever (start lever) and a tension lever is described as the fuel in the fuel injection pump. It is described that the adjustment is performed by a bimetal that is bent at 180 ° and deforms according to the temperature. However, this conventional technique is intended to prevent the fuel injection amount from excessively decreasing at the time of idle rotation after the completion of warm-up of the diesel engine, resulting in unstable rotation (rotation drop). When the idle spring is compressed by the bimetal to increase the resilience of the idle spring, the fuel injection amount is increased and corrected as the fuel temperature rises. Therefore, this prior art is completely different in purpose from the present invention, and does not solve the above-mentioned problems, and the bimetal used therein has a direction opposite to that of the bimetal in the present invention described in detail later. It is designed to work. In addition, Japanese Utility Model Publication No. 59-36664 discloses a configuration that is similar to the present invention, but this also does not solve the above problems.

In view of the problems of the prior art, the present invention, in order to improve the startability at the time of cold starting of a diesel engine, increases and corrects the fuel injection amount at the time of starting, and in the normal operating range by the increase correction at the time of starting. An object of the present invention is to gradually decrease the increase correction amount of the fuel injection amount as the fuel temperature rises so as not to cause a problem.

[Means for solving problems]

As a means for solving the above-mentioned problems of the prior art, the present invention causes a plunger to reciprocate in the cylinder bore to change the volume of the pump chamber, and to suck fuel from the low pressure chamber into the pump chamber. A fuel injection pump that pressurizes fuel in the pump chamber and discharges the fuel to the outside, the fuel injection pump being slidably fitted to a projecting portion of the plunger toward the low pressure chamber, and being formed in the plunger and the pump chamber. A spill ring that can open and close a spill port that communicates with the low pressure chamber, a control lever that is pivotally supported by the casing of the fuel injection pump and that engages with the spill ring, and the control lever according to the pump rotation speed. A control means for rotationally displacing the spill ring to change the position of the spill ring, and a tension lever pivotally supported by the control lever. A lever restricting means for restricting the position of the tension lever, an idle spring provided between the control lever and the tension lever, and an adjusting mechanism for changing the elastic force of the idle spring, The adjusting mechanism has one end attached to the tension lever and the other end being a free end, and a spiral bimetal having at least one or more turns, and one end pivotally supported by the tension lever. Of the idler spring and the other end thereof forms a spring seat of the idle spring, and when the temperature of the fuel in the low-pressure chamber is low, the spiral bimetal is contracted and deformed. A support member that rotates to increase the compression amount of the idle spring and the tension lever And a stopper that abuts against the other end of the support member when the temperature of the fuel in the low-pressure chamber is high, and that restricts excessive extension of the idle spring due to extensional deformation of the spiral bimetal. An injection amount control device for a fuel injection pump is provided.

[Action]

During cold start, when the temperature of the fuel in the low-pressure chamber of the fuel injection pump is low, the spiral bimetal shrinks and deforms, its free end abuts one end of the support member, and the support member is pressed to rotate and displace. Let As a result, the spring seat at the other end of the support member compresses the idle spring, and the amount of compression increases and the elastic force increases, so that the control lever rotates with respect to the tension lever and the spill ring on the plunger. To improve the startability in cold weather and the stability of rotation of the diesel engine by increasing and correcting the fuel injection amount.

As the temperature of the fuel in the low-pressure chamber of the fuel injection pump rises, the spiral bimetal expands, reducing the amount of compression of the idle spring by the spring seat at the other end of the support member and reducing its resilience. Therefore, the relative rotation amount of the control lever with respect to the tension lever also decreases, the spill ring moves toward the normal position on the plunger, and the increase correction amount of the fuel injection amount gradually decreases.

Furthermore, the temperature of the fuel in the fuel injection pump becomes higher,
When the spiral bimetal expands, the other end of the support member comes into contact with the stopper to prevent the idle spring from expanding further, and the increase of the fuel injection amount for temperature correction is completed, and the spiral bimetal becomes free. The end is free to extend away from one end of the support member. Therefore, after that, the fuel injection amount is controlled independently of the bimetal, and the influence of the correction correction of the fuel injection amount at cold start affects the normal operating state of the diesel engine and It is possible to prevent the characteristics of the bimetal from changing due to an unreasonable force.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 3 shows a fuel injection pump to which an embodiment of the present invention is applied, and has the same configuration as a conventionally known fuel injection pump except for the adjusting mechanism 200.

The field pump 101 is rotationally driven by a drive shaft 102 that is driven via the engine, and supplies the liquid fuel flowing in from the direction of arrow A into the low pressure chamber 103. Plunger 104
Is slidably supported in a cylinder bore 107 of a tubular member 106 provided in a casing 105, is rotatable around an axis, and moves back and forth in the axis direction, and is formed by a plunger 104 and a cylinder bore 107. By expanding and contracting the pump chamber 108, the fuel sucked from the low pressure chamber 103 via the suction passage 109 is pressure-fed to the injection valve (not shown) via the distribution passage 110 and the delivery valve 111. The injection valve opens, for example, according to the pressure of the fuel, and injects this fuel.

The plunger 104 is rotationally driven by the drive shaft 102, and the face cam 112 provided on the base portion is engaged with the roller 113 to move back and forth in the axial direction. Face cam 112
Is constantly urged to the left in the figure by a spring 114 provided between it and the inner wall of the casing 105 to engage with the roller 113, which causes the plunger 104 to rotate around the axis and to move to the face cam. It moves back and forth according to the shape of the cam surface of 112.

A spill port 115 that allows the pump chamber 108 and the low-pressure chamber 103 to communicate with each other is formed at the base side of the plunger 104, that is, the protruding portion to the low-pressure chamber 103. The short cylindrical spill ring 120 is slidably fitted to the plunger 104 to open and close the spill port 115. That is, when the plunger 104 moves back and forth, the spill port 115 is opened and closed by the spill ring 120.

Then, when the plunger 104 moves back and forth to discharge the fuel to the outside, the discharge of the fuel starts when the plunger 104 moves to the right and starts compressing the pump chamber 108, and then the plunger 104 moves to the right to move to the spill port. 115 is a spill ring 120
It ends when the inside of the low pressure chamber 103 is opened from the right end of the. That is, the position of the spill ring 120 determines the amount of fuel recirculated from the pump chamber 108 to the low pressure chamber 103, that is, the amount of fuel supplied from the pump chamber 108 to the injection valve.

Next, a governor mechanism for changing the position of the spill ring 120 will be described.

The governor lever 121 is connected to the casing 105 via the pin 122.
The control lever 124 and the tension lever 125 are pivotally supported via a pin 123 located on the spill ring 120 side of the pin 122. Control lever 1
24 has a protrusion 126 at the lower end, and this protrusion 126 fits into a recess 127 formed on the outer peripheral surface of the spill ring 120. Therefore, when the control lever 124 is displaced, the spill ring 120 is displaced and the fuel discharge amount is changed.

A start spring 128 made of a leaf spring is attached to the control lever 124, and the spring 128 engages with the tension lever 125. An idle spring 129 is provided between the tip of the control lever 124 and the tension lever 125.
The elastic force is adjusted according to the temperature by the adjusting mechanism 200 described later. A connecting member 130 is attached to the tip of the tension lever 125.
The control spring 131 attached to the connecting member 130 is coupled to the rotating shaft portion 133 of the adjusting lever 132 rotatably supported by the casing 105. A damper spring 134 is provided between the connecting member 130 and the tension lever 125.

Therefore, the adjusting lever 132 is attached to the rotary shaft portion 1
Control spring 13 by rotating it around the axis of 33.
When tension is generated in 1, the tension lever 125 is rotationally displaced counterclockwise in the figure via the connecting member 130 and the damper spring 134. The counterclockwise rotation of the tension lever 125 is restricted by the stopper 135.

The control lever 124 is engaged with the governor sleeve 140, and the governor sleeve 140 is guided by the governor shaft 141 to move back and forth to displace the control lever 124. The governor shaft 141 is rotatably supported by a casing 105 around its axis, and a gear 142 fixed to the shaft 141 meshes with a gear 143 fixed to the drive shaft 102 to rotate, whereby the governor shaft 141 is rotationally driven. In the holder 144 provided on the governor shaft 141, the shaft 14
The flyweight 145 that spreads outward is accommodated by the centrifugal force generated by the rotation of 1, and the governor sleeve 140 engages with this flyweight 145. Governor shaft 141
When the fly weight 145 spreads by rotating, the governor sleeve 140 is displaced along with it and the control lever 124
Is pressed.

1 and 2 are enlarged views showing an adjusting mechanism 200 for changing the elastic force of the idle spring 129 according to the temperature of the fuel in the low pressure chamber 103, and the structure in the vicinity of this mechanism 200.

The support member 201 fixed to the front surface 125a of the tension lever 125 has a pair of flange portions 201a and 201b, and a pin 203 is fixed to the flange portions 201a and 201b via a ring member 202. The pin 203 is parallel to the pin 123 connecting the tension lever 125 and the governor lever 121. The support member 204 includes a support portion 204a rotatably supported by the pin 203 and a lever 204b fixed to the support portion 204a.
Has a protrusion 204c with which a bimetal 210 described later can be engaged and a spring seat 204d with which the idle spring 129 is locked. The opposite surface 204e of the spring seat 204d is a tension lever.
It can be locked by a stopper 205 attached to the front surface 125a of the 125, and this restricts the clockwise rotational displacement of the lever 204b (Fig. 1).

One side of the tension lever 125 is bent and the flange part 1
25c is formed, and the spiral wound bimetal 210 is supported by the protrusion 206 formed on the outer surface of the flange portion 125c. The bimetal 210 extends around the protrusion 206 several times and extends above the protruding portion 204c of the lever 204b, and a pressing member 211 for pressing the upper surface of the protruding portion 204c is fixed to the tip end portion. The pressing member 211 faces the protrusion 204c with a gap at a relatively high temperature.

The bimetal 210 strengthens the degree of eddy winding when the temperature is low, and weakens the degree of eddy winding that tends to extend straight when the temperature is high. Therefore, the low pressure chamber 10
When the fuel temperature in 3 is low, the pressing member 211 of the bimetal 210
Is displaced downward in the figure, and as a result, the protrusion 204c is pushed down, the lever 204b is rotationally displaced counterclockwise, and the spring member 204d is displaced leftward to compress the idle spring 129. That is, the resilience of the idle spring 129 increases.
On the other hand, when the fuel temperature in the low pressure chamber 103 is high, the pressing member 211 of the bimetal 210 is displaced upward in the figure, and as a result,
The pressing member 211 is separated from the protruding portion 204c, and the lever 204b is rotationally displaced clockwise. Therefore, the spring seat 204d is displaced to the right, releasing the idle spring 129 and reducing its resilience.

Since the governor mechanism is configured as described above, it operates as follows to change the fuel injection amount.

When starting the engine, first, adjust lever 132
Control spring 131
To generate tension. Then, the tension lever 125 is rotationally displaced counterclockwise and locked by the stopper 135 and stopped. At this time, the control lever 124 is pressed against the governor sleeve 140 by the action of the start spring 128,
This causes the flyweight 145 to be completely closed. In this way, the control lever 124 is rotationally displaced counterclockwise about the pin 123 as compared with the non-actuated state, whereby the spill ring 120 is displaced rightward in the drawing. When the engine is started in this state, the increased fuel is discharged from the fuel injection pump, and the fuel injection amount at this time is represented by the straight line ab in FIG.

After starting the engine, return the adjusting lever 132 to the idle position, which
The tension of 131 becomes almost zero. Therefore, the control lever 124 is rotationally displaced clockwise about the pin 123,
The spill ring 120 moves to the left. The tension lever 125 also rotates clockwise around the pin 123 and separates from the stopper 135. Since the tension of the control spring 131 is almost zero, the flyweight 145 spreads outward even when the pump rotation speed is low, and the governor sleeve 140 is displaced to the right as the rotation speed increases. That is, the spill ring 120 is displaced to the left, and the flyweight 145
It stops at the place where the centrifugal force of and the elastic force of each of the start spring 128 and the idle spring 129 are balanced. The fuel injection amount at this time is represented by the curve gh in FIG.

As described above, the injection amount characteristic during idle operation is represented by abgh in FIG.

When the adjusting lever 132 is moved to the full position during full load operation, the tension of the control spring 131 increases and the tension lever 125 is locked to the stopper 135. When the number of rotations of the pump increases, the flyweight 145 expands due to the centrifugal force, and the governor sleeve 140 tries to protrude to the right. The amount of protrusion of the governor sleeve 140 at this time is determined by the balance between the centrifugal force of the flyweight 145 and the elastic forces of the start spring 128 and the idle spring 129. Then, the control lever 124 is rotationally displaced clockwise, and the position of the spill ring 120 is determined by this. The injection amount at this time is represented by the curve cd in FIG.

When the pump speed further increases, the flyweight 14
The governor sleeve 140 is further projected by the centrifugal force of 5, and the control lever 124 compresses the start spring 128 and the idle spring 129 and locks the tension lever 125, and the position of the spill ring 120 is determined. After that, even if the pump speed increases, the control spring
Since 131 acts, the control lever 124 is not rotationally displaced, and the position of the spill ring 120 becomes substantially constant.
The injection amount at this time is represented by the straight line de in FIG.

In addition, the pump speed increases and the fly weight 145
When the centrifugal force of overcomes the control spring 131, the control lever 124 and the tension lever 125 are pin 123.
Rotate clockwise around the center to displace the spill ring 120 to the left. Therefore, the spill port 115 is opened earlier when the plunger 104 moves forward, and the fuel injection amount sharply decreases as the pump rotational speed increases. The injection amount at this time is represented by the curve ef in FIG.

As described above, in the characteristic curve of FIG. 4, the portions of the curves gh and cd are the portions on which the idle spring 129 acts. In this embodiment, as described above, the low pressure chamber 103
Since the elastic force of the idle spring is increased as the internal fuel temperature becomes lower, the fuel injection amount increases in the idle operation at the cold start and changes along the curve g'h '. Therefore, smooth idle operation is performed.
On the other hand, during normal operation, if the fuel temperature rises, the fuel injection amount changes along the curve abcded, and at the pump rotational speeds N _{1 to} N ₂ ′ along the curve c′d ′ as in the conventional case. It is not increased and there is no risk of smoke.

As described above, in the present embodiment, the adjusting mechanism 200 having the bimetal 210 is added to the conventional governor mechanism, and it is not necessary to remodel the conventional device. The fuel temperature when increasing the injection amount can be easily changed by adjusting the mounting angle of the bimetal 210 in the gap between the pressing member 211 of the bimetal 210 and the protruding portion 204c of the lever 204b. The characteristic curve of injection quantity (Fig. 4) is
It can be changed by changing the zero displacement-temperature characteristic.

〔The invention's effect〕

As described above, according to the present invention, the fuel injection pump that increases the fuel injection amount in the full load operation and the idle operation at the cold start and does not increase the fuel injection amount from the normal amount during the normal operation. Can be obtained.

[Brief description of drawings]

1 is an enlarged side view showing an adjusting mechanism according to an embodiment of the present invention, FIG. 2 is a front view of the adjusting mechanism of FIG. 1, and FIG. 3 is an adjusting mechanism shown in FIGS. 1 and 2. FIG. 4 is a cross-sectional view showing a fuel injection pump to which the mechanism is applied, and FIG. 4 is a graph showing changes in the fuel injection amount with respect to the pump rotation speed. 104 …… Plunger, 107 …… Cylinder bore, 108 …… Pump chamber, 115 …… Spill port, 120 …… Spill ring,
124 …… control lever, 125 …… tension lever, 129 …… idle spring, 131 …… control spring (lever regulating means), 145 …… flyweight (control means), 200 …… adjusting mechanism, 204 …… support member ,
204d …… Spring seat, 210 …… Bimetal.

Claims (1)

(57) [Claims] 1. A fuel injection in which a plunger reciprocates in a cylinder bore to change the volume of the pump chamber, sucks fuel from the low pressure chamber into the pump chamber, pressurizes the fuel in the pump chamber, and discharges the fuel to the outside. A spill pump, which is slidably fitted to a protruding portion of the plunger toward the low pressure chamber, and which can open and close a spill port formed in the plunger to connect the pump chamber and the low pressure chamber. A ring, a control lever pivotally supported by the casing of the fuel injection pump and engaged with the spill ring, and a control means for rotationally displacing the control lever according to a pump rotation speed to change the position of the spill ring. , A tension lever pivotally supported by the control lever, and a lever regulating hand for regulating the position of the tension lever And an idle spring provided between the control lever and the tension lever, and an adjusting mechanism that changes the elastic force of the idle spring. One end of the adjusting mechanism is attached to the tension lever. And the other end is a free end, and the spiral bimetal having at least one or more turns is pivotally supported by the tension lever, and one end is engageable with the free end of the bimetal. At the same time, the other end forms the spring seat of the idle spring, and when the temperature of the fuel in the low pressure chamber is low, it rotates in accordance with the contraction deformation of the spiral bimetal to reduce the compression amount of the idle spring. When the temperature of the fuel in the low pressure chamber is high, it is formed integrally with the supporting member for increasing and the tension lever. An injection amount of a fuel injection pump, comprising: a stopper that is in contact with the other end of the support member and restricts excessive extension of the idle spring due to extension deformation of the spiral bimetal. Control device.