JPS5822993Y2 - Injection timing adjustment device for distributed fuel injection pump - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an injection timing adjustment device for a distribution type fuel injection pump for internal combustion engines and open use.

A distribution type fuel injection pump installed in an injection type internal combustion engine such as a diesel engine is equipped with a timer piston that is activated by oil pressure that changes in relation to engine rotation.
The injection timing is advanced as the engine speed increases.

By the way, in this type of engine, if the injection timing is rapidly advanced due to the operation of the timer piston due to the sudden increase in oil pressure during sudden acceleration, the combustion temperature will rise and the concentration of nitrogen oxides (NOx) in the exhaust gas will increase. There is a problem that it increases.

In this case, if the response of the timer piston to changes in oil pressure is slowed down by using an orifice to narrow the passage that leads the oil pressure to the pressure oil chamber formed at one end of the timer piston, the oil pressure will suddenly increase during sudden acceleration. However, the operation of the timer piston is delayed and the angle can be advanced gradually, which eliminates the above-mentioned problem.

However, in this case, it is difficult to properly delay the injection timing by pressing the button during deceleration.

The present invention was devised in view of the above circumstances, and is designed to provide a pressure path that acts on the timer piston, such as the hydraulic pressure path or the return path of a chamber formed on the side opposite to the side where this hydraulic pressure acts. In addition, a valve device configured to reduce the passage area when transmitting pressure related to the movement of the timer piston in the advance direction, specifically, a distributed fuel injection system in which a so-called one-way delay valve is inserted in a predetermined direction. It provides pumps.

Embodiments will be described in detail below according to embodiments shown in the drawings.

In the distribution type fuel injection pump shown in FIGS. 1 and 2, fuel oil is sucked and pressurized from a fuel tank 1 by an oil feed pump 2, and is supplied to a suction space 4 in a pump Ujifugu 3.

Since the internal pressure of the suction space 4 is controlled by the pressure control valve 5 in relation to the engine speed, as is well known, the internal pressure increases as the engine speed increases.

A pump/dispensing plunger 7 is installed in the sliding hole 6 in the pump puffer fish 8, and this plunger 7 is caused to reciprocate and rotate at the same time by means to be described later.

That is, a drive shaft (not shown) and a cam disk 8 fixed to the end of the plunger 7 are connected in the rotational direction via the driving disk (not shown), and the number of cylinders of the engine formed on the cam disk 8 is adjusted. By pressing a cam surface having a corresponding peak against a roller 10 held in a fixed roller holder 9 by a plunger spring (not shown), the plunger 7 is provided with a reciprocating motion for sucking and pumping fuel and for distributing fuel. The rotation for the purpose is performed at the same time.

When the plunger 7 is in the suction stroke (downward movement in FIG. 1), fuel in the suction space 4 flows from the supply hole 11 to the plunger 70.
It is supplied to the plunger chamber 13 through one of the plurality of vertical grooves 12 provided on the outer peripheral surface of the head.

When the plunger 7 moves to the pressure stroke (upward movement in FIG. 1), the supply hole 11 and the vertical groove 12 are separated, and the plunger chamber 1
The fuel No. 3 is compressed and supplied from the vertical hole 14 in the plunger 7 through the distribution vertical groove 15 to one of the discharge holes 17 (provided for the number of cylinders in the circumferential direction) equipped with a check valve 16. Then, it is injected into the cylinder from an injection nozzle (not shown).

A control sleeve 18 is slidably fitted in the part of the plunger T that protrudes toward the suction space 4 side, and a cut-off port 1 connected to the vertical hole 14 of the plunger 7 is fitted.
When the control sleeve 9 comes off the upper edge of the control sleeve 18 and opens into the suction space 4, the fuel flows out into the suction space 4, and therefore the delivery to the discharge hole 17 side is stopped and becomes an injection path.

This control sleeve 18 is adjusted in position on the plunger T by a well-known governor mechanism (not shown) via a lever 20 that engages with the control sleeve 18, thereby changing the injection path, that is, increasing or decreasing the injection amount. Can be controlled.

On the other hand, the roller holder 9 is rotatably provided concentrically with the plunger 7, and one point of action of a lever 22 that swings about a fixed shaft 21 is engaged with the roller holder 9, and the other point of action is engaged with the piston 23. match.

Each end of the piston 23 has a chamber 2 containing a spring 24.
5, and a pressure oil chamber 26 on which the oil pressure in the suction space 4 acts, and the position of the piston 23 and thus the circumferential position of the roller holder 9 via the lever 22 is determined in relation to the force of the spring 240 and the oil pressure. It is now possible to do so.

Due to the change in the circumferential position of the roller holder 9, the contact position between the roller 10 and the cam surface of the cam disk 8 changes, and the operating position of the plunger 7 is determined by the circumferential phase of the drive shaft and the contact position. As a result, the injection timing can be changed relative to the rotation of the drive shaft.

In this case, the piston 23 is moved by the spring 2 due to hydraulic pressure.
4, the roller holder 9 is rotated clockwise and the injection timing is advanced.

Here, the hydraulic pressure in the suction space 4 is transmitted from an opening 27 on the side of the piston 23 through a hydraulic passage 28 provided in the axial direction of the piston 23 so as to communicate the opening 27 and the pressure oil chamber 26. You will be led to room 26.

In the first embodiment of the present invention shown in FIG. 3, this hydraulic passage 28 is formed between a small diameter part of a stepped hole bored in the axial direction of the piston 23 body and a barrel embedded in a large diameter part of the stepped hole. 31, and the inner hole of the barrel 31 is composed of a large diameter portion on the side of the stepped pin J and the diameter portion, and a small diameter portion on the pressure oil chamber 26 side.

A valve body 32 is slidably disposed along the large diameter portion of the inner hole of the barrel 31, and a spring 33 is interposed between the back of the valve body 32 and the stepped portion of the stepped hole of the piston 23 body. has been done.

In this way, the valve body 32 is normally biased by the spring 33, and the valve body 32 is pressed against the seat surface 34 formed in the stepped portion of the inner hole of the barrel 31.

A small-diameter through hole 35 is bored in the axial direction of the valve body 32, and even when the valve body 32 is pressed against the seat surface 34, the hydraulic passage 28 is opened through this through hole 35. .

However, in this case, the through hole 35 has the smallest diameter in the hydraulic passage 28 and limits the transmission of hydraulic pressure.

Moreover, between the outer peripheral surface of the valve body 32 and the inner hole of the barrel 31,
As shown in FIG. 4, a gap 36 is provided in the axial direction except for a part of the sliding surface.

Therefore, when the valve body 32 separates from the seat surface 34,
A gap 36 opens in parallel with the through hole 35, and since the total flow area of the gap 36 is sufficiently larger than that of the through hole 35, the hydraulic passage 28 is made substantially large in diameter, and the hydraulic pressure is transmission with almost no response delay.

In this configuration, when the oil pressure in the suction space 4 suddenly increases during acceleration, the oil pressure on the back side of the valve body 32 increases momentarily, and together with the action of the spring 33, the valve body 32 moves to the left in FIG. and comes into contact with the seat surface 34.

Therefore, at this time, pressure oil passes through the hydraulic passage 28 to the pressure oil chamber 2.
Since the flow only passes through the small-diameter through hole 35 when the oil reaches the 100mm, pressure transmission is delayed, and even if the oil pressure in the suction space 4 suddenly increases, the oil pressure in the pressure oil chamber 26 that acts on the piston 23 will be gradual. Rise.

Therefore, the speed of advancing the injection timing during rapid acceleration can be slowed down, thereby avoiding problems such as an increase in the amount of NOx emissions described in 7 above.

In addition, when the oil pressure in the suction space 4 decreases during deceleration, the pressure inside the pressure oil chamber 26 becomes higher, so the valve body 32 is moved to the right in FIG. 3 against the spring 33 and separated from the seat surface 34. let

Therefore, at this time, the gap 36 is opened and the pressure oil chamber 26 is opened.
The pressure oil inside is quickly discharged into the suction space 4 through this.

Therefore, the oil pressure change in the oil pressure space 4 acting on the piston 23 can be followed without response delay, that is, the injection timing can be appropriately and promptly delayed during deceleration.

FIG. 5 shows a second embodiment of the invention.

A chamber 25 housing a spring 24 opposing the piston 23 on the opposite side from the pressure oil chamber 26 has a return passage 29 for the purpose of maintaining its internal pressure at a predetermined pressure and discharging leaked oil.
It is connected to the suction side of oil pump 2, etc.
Here, the return passage 29 is modified so that when the oil pressure in the suction space 4 rises and the piston 23 moves to the right in FIG.
is pressed against the valve seat 42.

At this time, the pressure inside the chamber 25 escapes through the small diameter through hole 43 provided in the center of the valve body 41, so the pressure inside the chamber 25
The pressure inside 5 remains high for a while, and this acts to prevent the piston 23 from moving to the right.

Therefore, even if the oil pressure in the suction space 4 rises rapidly during rapid acceleration and attempts to move the piston 23 in the advance direction, the damper effect of the pressure confined within the chamber 25 for a certain period of time slows down the movement of the piston 23 in the advance direction. It can be done.

Also, if the oil pressure in the suction space 4 decreases, the piston 2
3 moves to the left in FIG. 5, but when the pressure inside the chamber 25 decreases at this time, the valve body 41 is attracted to the left against the force of the weak spring 44, and the valve body 41 separates from the valve seat 42. Therefore, the flow area of the return passage 29 becomes large, and the pressure is quickly guided to prevent a large negative pressure from being generated in the chamber 25.

Therefore, when the oil pressure in the suction space 4 decreases during deceleration and the piston 23 is to be moved in the retarded direction, the pressure in the chamber 25 can be prevented from interfering with the movement.

A cylindrical distributor that is rotatably moved by an engine has a pair of plungers facing each other on the sides, and the plunger of the distributor runs over the inner cam surface of a cam ring provided surrounding the plungers. Even in distribution type fuel injection pumps, which suck and pump fuel by the reciprocating motion of the plunger that rotates through a roller interposed between the plunger and the plunger, the cam ring, which is the injection timing control member, is moved around the circumference. It goes without saying that similar effects can be obtained if the present invention is applied to a timer piston that is displaced in the same direction.

As explained above, according to the present invention, by making the speed of the timer piston in the advance direction slower than the speed in the retard direction, the degree of advance of the injection timing is delayed during acceleration. It is possible to eliminate problems such as an increase in the amount of NOx emissions, and also to appropriately and quickly retard the injection timing during deceleration.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of essential parts showing an example of a distribution type fuel injection pump to which the present invention is applied, Fig. 2 is a cross-sectional view taken along the -■ arrow in Fig. A cross-sectional view of a timer piston showing an embodiment, FIG. 4 is a cross-sectional view taken in the direction of the ■÷■ arrow in FIG.
FIG. 5 is a cross-sectional view of a timer piston showing a second embodiment of the present invention. 3... Pump housing, 4... Suction space, 7...
...Plunger, 8...Cam disc, 9...Roller holder, 23...Piston, 26...Pressure oil chamber, 2
8... Hydraulic passage, 29... Return passage, 32.41.
...Valve body.

Claims (3)

[Scope of utility model registration request] (1) 'The pressure that acts on the timer piston in a distribution type fuel injection pump that controls the injection timing by driving the injection timing control member by the timer piston that is operated by oil pressure that changes in relation to engine rotation. In the aisle of
1. An injection timing adjustment device for a distribution type fuel injection pump, characterized in that a valve device is installed to reduce a passage area when transmitting pressure related to movement of a timer piston in an advance direction. (2) Injection timing adjustment of the distribution type fuel injection pump according to claim 1, wherein the valve device is interposed in a passage that guides the hydraulic pressure to a pressure oil chamber formed at one end of the timer piston. Device. (3) Injection timing adjustment of the distribution type fuel injection pump according to claim 1, wherein the valve device is interposed in a return passage of a chamber on the opposite side of the timer piston to the side on which the hydraulic pressure acts. Device.