JPS6321358A - Distribution type fuel injection pump - Google Patents

Abstract

PURPOSE:To obtain a distribution type fuel injection pump which can optionally change injection timing by providing a planetary gear mechanism in between the driving shaft of said distribution type fuel injection pump and a cam, and varying the fixed position of a ring gear which is a part of said mechanism. CONSTITUTION:Due to the rotation of a driving shaft 5, pinions 11a-11d which are meshed with a sun gear 9 on the end part of the shaft 5 and a ring gear 10, rotate a carrier 13 while rotating on their own axes. At the same time, a cam 16 is rotated, and the reciprocating movement of a plunger 23 causes fuel to be sucked in from a suction passage 31, to become a high pressure fuel, and to be discharged out of discharge passages 33, 34. The gear ratio of the sun gear 9 to the ring gear 10 is determined 1/2. The control of injection timing is carried out by rotating a worm gear meshed with a worm wheel on the outer periphery of the ring gear 10 by means of a stepping motor 19. Since the phases of the carrier 13, cam 16, and plunger 23 can be changed respectively enabling a suction timing and a discharge timing to be adjusted simultaneously, the injection timing can be optionally adjusted without limitation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a distribution type fuel injection pump used in a fuel injection device for an internal combustion engine.

(Prior art) In an internal combustion engine, the timing of injection into the cylinder depends on the output,
Since it has a large effect on fuel efficiency, exhaust gas, noise, etc., it is necessary to accurately match the overall optimum value. A timer is provided to adjust the injection timing by advancing the injection timing, and as shown in Japanese Patent Application Laid-Open No. 53-44724, this timer is used to move the roller holder in a distribution type fuel injection pump. A conventional example having such a timer is shown in FIG.

In FIG. 3, a disk-shaped cam 16 is engaged with the drive shaft 5 in the radial direction, and a plunger 23 is fixed to this cam 16. This plunger 23 is fitted into a barrel 24, and the plunger 23 is and the barrel 24 create a high pressure chamber 2.
9 are configured.

The cam 16 comes into contact with a roller 22, which is supported by the roller holder 20, so that when the drive shaft 5 rotates, the plunger 23 rotates back and forth. The plunger 23 is formed with a suction group 30 that communicates with the high pressure chamber 29 and a distribution boat 33, and the suction group 30 communicates with the suction passage 31 during the suction stroke when the plunger 23 retreats, so that fuel is supplied from the suction space 40 in the housing 1. is sucked into the high pressure chamber 29. Further, the distribution boat 33 is connected to the plunger 2.
3 aligns with the distribution passage 34 during the forward discharge stroke and opens the delivery valve 41 to deliver fuel.

The suction group 30 communicates with the suction passage 31 only during the suction stroke, and the distribution boat 33 communicates with the distribution passage 34 only during the discharge stroke to prevent backflow of fuel.

The timer T has a timer piston 43 that is slidable within a timer cylinder 42, and this timer piston 43 is connected to the aforementioned roller holder 20 via a lever 44. The timer cylinder 42 receives pressure-adjusted fuel from a feed pump 45 through a regulating valve (not shown) flowing into the suction space 40, moves the timer piston 43 according to the rotational speed of the internal combustion engine, and moves the timer piston 43 to the roller holder. 20 to change the phase between the cam 16 and the roller 22. As a result, as shown in Fig. 4, the cam curve slides to the left as shown by the dotted line after the advance, compared to the cam diagram before the advance (not shown by the solid line), and the plunger lifts. In other words, the injection timing is brought forward.

(Problems to be Solved by the Invention) However, in the above conventional example, the roller holder 2
Since the injection timing is adjusted by rotating the rotation angle θ of the drive shaft 5, the discharge timing that matches the distribution boat 33 and distribution passage 34 and the suction group 30 and suction passage 31 are adjusted. The suction timing at which the two coincide with each other remains unchanged, and only the phase of the reciprocating motion of the plunger 23 changes.

On the other hand, as described above, the distribution boat 33 must be communicated with the distribution passage 34 only during the discharge stroke of the plunger 23, and the suction group 30 must be communicated with the suction passage 31 only during the suction stroke, so as shown in FIG. In addition, the distribution boat 33 of the plunger 23 starts alignment in the distribution passage 34 at the earliest at the top dead center of θ1 before the advance angle, and finishes alignment at the latest at the bottom dead center of θ2 after the advance angle. , the suction group 30 of the plunger 23 starts alignment at the bottom dead center of θ at the latest before the suction passage 31 is advanced;
After the advance, the above-mentioned discharge timing and suction timing are set so that alignment is completed at the top dead center of e4 at the earliest. Therefore, the advance angle amount by the timer is θ, ~θ2
Alternatively, the angle is limited to between θ3 and θ4, and cannot be advanced any further, and is limited to about 106. This is because if the fuel angle is advanced any further, the suction group 30 and the suction passage 31 will communicate with each other during the discharge stroke, for example, and the fuel in the high pressure chamber 29 may flow back into the suction space 40. Therefore, considering the characteristics of the internal combustion engine, it may be advantageous to advance the angle further, but since the amount of advance is limited, the problem is that the optimum injection timing cannot be obtained. There it was.

Therefore, it is an object of the present invention to solve the above-mentioned problems and provide a distribution type fuel injection pump that can arbitrarily change the injection timing.

(Means for Solving the Problems) However, the gist of the present invention is to provide a distribution fuel injection pump in which a plunger is connected to a drive shaft via a cam. The planetary gear mechanism is interposed therebetween, and a driving means for changing the fixing position of the ring gear constituting the planetary gear mechanism is provided.

(Function) Therefore, when the fixed position of the ring gear is changed by the driving means, the relative rotational position of the drive shaft, cam, and plunger changes, and the suction timing and discharge timing with respect to the rotation angle of the drive shaft can be changed. , it is possible to achieve the above problems.

(Embodiment) An embodiment of the present invention is shown in FIGS. 1 and 2, in which a cylindrical housing 1 has a head 2 and a lid 3 fixed to both ends of the housing 1. and a radial bearing 4a on the lid body 3.

A drive shaft 5 is rotatably supported via 4b. One end of the drive shaft 5 protrudes from the lid 3 to receive driving force from a four-cycle internal combustion engine (not shown), and a pulser 6 is provided near the center of the drive shaft 5. An electromagnetic pickup 7 is provided in the housing 1 so as to face the drive shaft 6, and the rotation speed of the drive shaft 5 is detected by this electromagnetic pickup 7.

The planetary gear mechanism 8 includes a sun gear 9 formed around the other end of the drive shaft 5, a ring gear 10 provided along the inner circumference of the housing 1, and, for example, four pinions 112 that mesh with the sun gear 9 and the ring gear 10. ~ has lid. Carrier pins 12a to 12d are rotatably inserted into the centers of the binions lla to 11d, and carriers 13 are similarly rotatably inserted into the carrier pins 12a to 12d. This carrier 13 has claws 14a and 14b formed on the opposite side of the carrier 13,
The pawls 14a and 14b engage with a cam 16, which will be described later, via a coupling 15 in the radial direction so as to allow the cam 16 to move in the axial direction. Sun gear 9 and ring gear 10 above
The ratio of the number of teeth is set to 1:2, so that the cam 16 rotates at 1/2 of the rotational speed of the drive shaft 5.

Furthermore, teeth are formed on a part of the outer periphery of the ring gear 10 to constitute a worm wheel 17, and a worm gear 18 meshes with the worm wheel 17. The worm gear 18 is rotatably inserted into the housing 1, and the other end of the worm gear 18 is connected to a stepping motor 19.
This constitutes a driving means for moving the ring gear 10. This driving means is a stepping motor 19
By controlling the energization, the worm gear 18 is rotated, thereby the ring gear 10 is rotated, and the relative position of the drive shaft 5 and the cam 16 in the radial direction is changed.

The roller holder 20 is provided so as to surround the carrier 13 described above, and is fixed to the housing 1 by a fixing pin 21. This roller holder 20 has a plurality of rollers 22.
is rotatably supported, and a disc-shaped cam 16 is in contact with this roller 22. This cam 16 is
A plunger 23 as described below is attached to the periphery that comes into contact with the roller 22.
A cam portion is formed for reciprocating. The cam diagram of this cam portion is similar to the conventional example shown in FIG.

The plunger 23 is slidably inserted into the barrel 24 fixed to the head 2 described above, and the plunger 23
The base of the cam 16 is fixed to the cam 16 to prevent movement in the radial direction. Between the base of the plunger 23 and the head 2, there is a thrust bearing 25 provided at the periphery of the base of the plunger 23, a first spring receiver 26 that comes into contact with the thrust bearing 25, and one end of the first spring receiver 26. A plunger spring 27 that receives the plunger spring 27 and a second spring receiver 28 fixed to the head 2 so as to receive the other end of the plunger spring 27 are interposed.
The plunger 23 is configured to reciprocate and rotate along the cam surface.

The high pressure chamber 29 is surrounded by the plunger 23, the barrel 24, and a valve body 36 of a solenoid valve 35, which will be described later, and which is screwed to the center of the head 2 so that the barrel 24 is pressed. In the plunger 23, suction groups 30 whose one end opens into the high pressure chamber 29 are formed on the periphery in parallel with the axial direction in a number corresponding to the number of cylinders of the internal combustion engine.

This suction group 30 communicates with a suction passage 31 formed in the head 2 and the barrel 24 during the suction stroke of the plunger 23. The other end of the suction passage 31 is connected to a fuel tank via a feed pump. Further, the plunger 23 has a vertical hole 32 formed at its axial center, one end of which opens into the high pressure chamber 29, and the other end of the vertical hole 32 is connected to a distribution port 33 formed on the circumferential surface of the plunger 30. The distribution ports 33 are formed in the head 2 and the plunger barrel 24 in a number corresponding to the number of cylinders of the internal combustion engine.
4 during the discharge stroke of the plunger 23. The distribution passage 34 is provided with a delivery valve (not shown), and the other end is connected to a nozzle via an injection pipe.

The electromagnetic valve 35 has a valve body 36 screwed to the center of the head 2 , and a spill passage 37 is formed between the valve body 36 and the head 2 , one end of which is connected to the high pressure chamber 29 . A needle valve 38 is provided to open and close the needle valve 3.
8 is connected to an actuator section 39 containing an armature and a starter.

In the above configuration, when the drive shaft 5 is rotated, the sun gear 9 formed on the drive shaft 5 rotates, so the binions Ila to lid revolve around the sun gear 9 while rotating around the carrier pins 12a to 12d. , the carrier 13 rotates, and the cam 16 and plunger 23 connected thereto rotate while reciprocating according to the cam diagram of the cam 16. In this case, since the tooth ratio between the sun gear 9 and the ring gear 10 is set to 1:2, the plunger 23 rotates at 1/2 the rotation speed of the internal combustion engine, and the 4-cycle internal combustion engine and injection pump The pulley ratio connecting the pumps can be set to 1:1, and the diameter of the pulley on the pump side can be reduced.

During the suction stroke of the plunger 23, the suction port 30 and the suction passage 31 communicate with each other, and fuel is sucked into the high pressure chamber 29.

Next, when the plunger 23 enters the discharge stroke, the communication between the suction port 30 and the suction passage 31 is cut off, the distribution port 33 and the distribution passage 34 are communicated, and the spill passage 37 is closed by the solenoid valve 35. For example, fuel pressurized in the high pressure chamber 29 is forced into the nozzle via the vertical hole 32, the distribution port 33, and the distribution passage 34. At this time, when the spill passage 37 is opened by the electromagnetic valve 35, the fuel in the high pressure chamber 37 escapes to the tank side, and the pressure of the fuel in the high pressure chamber 37 suddenly decreases to end the pressure feeding, and the electromagnetic valve 35 injects the fuel. Amount controlled.

The injection timing is controlled by a stepping motor 19. When the worm gear 18 is rotated by this stepping motor 19 -, this worm gear 18
The ring gear 10 of the planetary gear mechanism 8 that is meshed with rotates. As a result, the drive shaft 5, carrier I3, and cam I6
Since the phases of the plunger 23 and the rotation angle of the drive shaft 5 are shifted, the suction timing at which the suction group 3o of the plunger 23 communicates with the suction passage 31 with respect to the rotation angle of the drive shaft 5 and the plunger 23
The discharge timing at which the distribution port 33 communicates with the distribution passage 34 is adjusted at the same time.

In the above embodiment, the present invention is applied to a so-called Bosch type distribution type fuel injection pump, but it can also be applied to a known inner plunger type fuel injection pump having a plunger in an inner cam.

(Effects of the Invention) As described above, according to the present invention, a planetary gear mechanism is interposed between the drive shaft and the cam, and the ring gear of the planetary gear mechanism is moved by the drive means to change the injection timing. Therefore, the injection timing can be adjusted arbitrarily and without restriction, and combustion in the internal combustion engine can be controlled more accurately.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along the line nn of Fig. 1, Fig. 3 is a longitudinal cross-sectional view showing a conventional example, and Fig. 4 is a conventional injection FIG. 3 is a diagram showing characteristics of timing control. 5... Drive shaft, 8... Planetary gear mechanism, 9... Sun gear, 10... Ring gear, lla~lid... Pinion, 13... Carrier, 14a, 14b... Pawl, 16...Cam, 17...Worm wheel, 18
...worm gear, 19...stepping motor,
23... Plunger.

Claims (5)

[Claims] 1. In a distribution type fuel injection pump in which a plunger is connected to a drive shaft via a cam, a planetary gear mechanism is interposed between the drive shaft and the cam, and the fixed position of a ring gear constituting this planetary gear mechanism is changed. A distribution type fuel injection pump characterized by being provided with a driving means. 2. The planetary gear mechanism includes a sun gear provided at one end of the drive shaft, a pinion that meshes with the sun gear and the ring gear, and a carrier connected to the pinion, and the carrier is provided with a pawl that engages with the cam. The distribution type fuel injection pump according to claim 1, characterized in that: 3. Claim 1 or 2, wherein the ring gear has a worm wheel formed on its outer periphery, and the driving means has a worm gear, and the worm gear meshes with the worm wheel. distribution type fuel injection pump. 4. 4. The distribution type fuel injection pump according to claim 1, wherein the driving means includes a stepping motor. 5. 3. The distribution type fuel injection pump according to claim 2, wherein the planetary gear mechanism has a sun gear and a ring gear with a tooth ratio of 1:2.