JPH04107479U - fuel injection pump - Google Patents

Abstract

(57) [Summary] [Purpose] When the engine is under low load, the fuel injection rate is reduced regardless of the engine speed. [Structure] Control edge 12a of upper lead 12 and lower lead 1
Regarding the control edge 14a of No. 4, the low load side (vertical groove 13 side)
The plunger 6 is inclined so as to move toward the rear end in the forward movement direction of the plunger 6 as it goes toward the high load side. However, the inclination angle of the control edge 14a is made larger than that of the control edge 12a so that the distance between the upper lead 12 and the lower lead 14 increases from the low load side to the high load side. Further, as a cam for reciprocating the plunger 6, a two-stage cam is used in which the lift speed is slow in the first half and fast in the second half.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea uses a two-stage cam to make the fuel injection rate variable. Regarding injection pumps.

0002

[Conventional technology]

As a conventional fuel injection pump of this type, for example, Japanese Patent Application Laid-Open No. 168958/1983 Some are listed in the official gazette. The fuel injection pump described in this publication has a plunger that moves A 2-stage cam is used as the cam for double movement, and a 2-stage cam is used as the delivery valve. The two-stage cam is shown in Figure 1 (B). As shown in the figure, the lift speed is slow in the first half and reaches maximum speed in the second half. It has speed characteristics. In addition, the delivery valve with Angleich has a suction volume that is equal to or greater than that of the engine. It has the characteristic that it is less when driving at low speeds and more when driving at high speeds.

0003 A fuel injection pump equipped with such a two-stage cam and a delivery valve with Angleich During low-speed, low-load operation such as idling, the suction back of the delivery valve is Since the amount is small, it is almost the same as the plunger being forced forward by the low speed range of the cam. Fuel injection is performed at the same time. In this case, the injection rate is It is low because the load speed) is slow. On the other hand, during high-speed, high-load operation, the suction back of the delivery valve Since the amount is large, the fuel pressurized by the forward movement of the plunger in the low speed range is sucked. It is spent on compensating for the return and is not injected. fuel injection plunge This is done when the motor is forced to move forward due to the high speed range. Injection rate in this case is high as the plunger is forced to move forward at high speed due to the high speed range of the cam. Become.

0004

[Problem that the idea aims to solve]

In the above conventional fuel injection pump, the injection rate at high speed and low load should be low. Despite this, there was a problem in that the injection rate became high. In other words, the delivery valve with angleich has a large amount of suction when the engine rotates at high speed. It becomes. Therefore, at high speed and low load, the forward movement of the plunger in the low speed range causes combustion. When I tried to inject the liquid, almost nothing was injected. Therefore, high speed At low loads, fuel injection is performed by forward movement of the plunger in the high speed range near the low speed range. I'm trying to get them to do it. However, since the high-speed range is used, it is not possible to lower the injection rate. I was unable to do so. This results in noise and nitrogen oxidation at high speeds and low loads. There was a problem that NOx was generated.

[0005] This idea was made to solve the above problem, and the It is possible to achieve a low injection rate not only at low speeds and low loads, but also at high speeds and low loads. The purpose of the present invention is to provide a fuel injection pump that has the following characteristics.

[0006]

[Means to solve the problem]

In order to achieve the above purpose, this device is reciprocated by a cam, When the outer circumferential surface covers the intake and exhaust hole that opens into the fuel pressurizing chamber during forward movement, the fuel in the fuel pressurizing chamber A plunger that pressurizes the The location on the outer circumferential surface of the plunger facing the suction/exhaust hole is changed depending on when the load is high (hereinafter referred to as , the locations that face each other during low load and high load are called the low load side and the high load side, respectively. ) rotational displacement mechanism, and the cam has a low-speed range where the lift speed is slow in the front half. It has a high speed region in the latter half where the lift speed reaches the maximum speed from a low speed region and then decreases. In a fuel injection pump using a cam, the outer peripheral surface of the plunger includes: Circumferentially from the low load side to the high load side at the tip and middle part in the forward direction. It forms an upper lead and a lower lead that extend in the direction. Each control edge adjacent to the lead in the axial direction of the plunger is connected to the plunger on the low load side. It is located at the tip side in the forward movement direction of the runger, and at the rear end side on the high load side. , the spacing between these control edges is narrow on the low load side and wide on the high load side. It is something.

[0007]

[Effect] When the engine is operating at low load, the low load side of the plunger is Rotatably displace the plunger so that it faces the suction/discharge hole. on the low load side of the plunger In this case, the control edge of the upper lead is located at the tip of the plunger in the forward direction. Therefore, while the plunger is being moved forward by the low speed range of the cam, the upper lift is The control edge of the guard moves away from the intake/discharge hole in the forward direction, and fuel injection begins. this place In this case, the injection rate is low because the injection is performed by the low speed range of the cam. Therefore , the injection rate becomes low not only at low speed and low load, but also at high speed and low load.

[0008]

【Example】

Hereinafter, embodiments of this invention will be described with reference to FIGS. 1 to 10. FIG. 2 shows an embodiment of the fuel injection pump according to this invention, and is designated by reference numeral 1. is the pump housing. This pump housing 1 has a structure from its upper end surface to its lower end. A hole 1a penetrating to the surface is formed. The upper end of this hole 1a has a cylindrical shape. Barrel 2 is inserted and fixed. The intermediate outer circumferential surface of this barrel 2 and the A fuel reservoir 3 is formed between the hole 1a and the inner circumferential surface of the hole 1a. This fuel pool 3 In this case, fuel is supplied from a feed pump (not shown) through fitting 4. It has become.

[0009] Inside the barrel 2, a delivery valve 5 is screwed and fixed to its upper end. A plunger 6 is inserted into the lower end so as to be slidable and rotatable within a predetermined range. The internal space of the barrel 2 defined by the delivery valve 5 and the plunger 6 is filled with fuel. It is referred to as a pressurizing chamber 7. This fuel pressurizing chamber 7 includes an intake and exhaust hole 2a formed in the barrel 2. It communicates with the fuel reservoir 3 via. In addition, as the delivery valve 5, A device with a constant amount of suction is used.

0010 The lower end of the plunger 6 protrudes downward from the barrel 2 and is supported by a spring 8. is brought into pressure contact with the cam portion 11 (cam) of the camshaft 10 via the roller assembly 9. being admired. Therefore, when the camshaft 10 rotates, the plate follows the rotation. The plunger 6 will reciprocate. In this case, the forward movement speed of the plunger 6 (lift speed) changes depending on the lift speed characteristics of the cam portion 11. As shown in Figure 1(B), after the lift speed reaches a predetermined speed, the speed is maintained at a constant speed. A low speed range that is maintained and a high speed range where the lift speed decreases after reaching the maximum speed from the low speed range. It is formed as a two-stage cam with

[0011] As shown in FIG. 1(A), the upper end of the outer peripheral surface of the plunger 6 (in the forward direction) An upper lead 12 extending in the circumferential direction is formed at the tip end portion). This top lead 1 The upper side of the plunger 2 is open to the upper end surface of the plunger 6. This allows the top The lead 12 is communicated with the fuel pressurizing chamber 7. On the other hand, the lower side of the upper lead 12 The side edge of is a control edge 12a for regulating the fuel injection start timing. The control edge 12a extends from one end side (hereinafter referred to as low load side) to the other end side (hereinafter referred to as high load side). It's called the side. ) toward the lower end of the plunger 6 (the rear end in the forward direction) It is slanted towards the sky.

0012 Also, on the outer circumferential surface of the plunger 6, there is a part that is slightly spaced apart from the end of the lower load side of the upper lead 12. A vertical groove 13 extending downward from the upper end surface of the plunger 6 is formed in the space between the two. and extends from the lower end of the vertical groove 13 in the same direction as the upper lead 12. A extending lower lead 14 is formed. The upper side edge of this lower lead 14 It is a control edge 14a for regulating the firing end timing, and this control edge 14a is It is inclined in the same direction as the control edge 12a of the upper lead 12. However, the control edge The angle of inclination of the control edge 14a is greater than the angle of inclination of the control edge 12a. This conclusion As a result, the distance between the upper lead 12 and the lower lead 14 increases from the low load side to the high load side. It is gradually spreading.

Further, as shown in FIG. 2, a control sleeve 15 is fitted to the lower end of the plunger 6 in a slidable but non-rotatable manner. This control sleeve 15 is adapted to be rotated by a control rod 16, and when the control sleeve 15 is rotated, the plunger 6 is rotationally displaced together with it. As a result, the location on the outer peripheral surface of the plunger 6 facing the suction/discharge hole 2a can be changed. In this case, as shown in FIG. 1(A), during low load such as idling, the outer peripheral surface of the plunger 6 is connected to the suction/discharge hole 2a on a line L1 passing through the center of the upper lead ₁₂ and the vertical groove 13. They are opposed to each other, and at the time of maximum load, they are rotated so as to face the suction/discharge hole 2a on a line _L2 passing through the high-load side ends of the upper lead 12 and the lower lead 14. As is clear from this point, the control sleeve 15 and the control rod 16 constitute a rotation mechanism.

[0014] Note that the control rod 16 is connected to a governor (not shown). With the governor, the location where the plunger 6 faces the suction/discharge hole 2a changes as shown above. It is controlled as follows.

[0015] Next, the operation of the fuel injection pump having the above configuration will be explained. As the camshaft 10 rotates, the plunger 6 starts to move forward, and the outer circumference of the plunger 6 When the surface covers the suction/discharge hole 2a, the plunger 6 pressurizes the fuel in the fuel pressurization chamber 7. starts. The pressurized fuel is delivered to a fuel injection nozzle (not shown) via a delivery valve 5. and is injected into the combustion chamber of the engine. During the forward movement of plunger 6, the lower lead The control edge 14a of 14 is located above the lower edge of the suction/discharge hole 2a, and the lower lead 14 is When the fuel in the fuel pressurizing chamber 7 comes to face the exhaust hole 2a, the fuel in the fuel pressurizing chamber 7 flows into the vertical groove 13 and the lower lead. 14 and the fuel reservoir 3 through the suction/discharge hole 2a. This allows fuel injection ends. Note that when the plunger 6 moves back, the fuel in the fuel reservoir 3 flows through the suction/discharge hole 2a and the lower lip. The fuel is sucked and introduced into the fuel pressurizing chamber 7 via the rod 14 and the vertical groove 13.

[0016] Here, the fuel injection start timing is determined at low load times such as when idling. This is when the upper end of the plunger 6 is located above the suction/discharge hole 2a, and under high load, the upper end of the This is when the control edge 12a of the door 12 is located above the suction/discharge hole 2a. In this case, the control The edge 12a is located on the rear end side in the forward movement direction of the plunger 6 on the high load side. Because of this, the injection start timing is earlier when the load is low, and the injection start timing is shorter when the load is high. Become slow.

[0017] Also, at the end of injection, the control edge 14a of the lower lead 14 is closer to the lower edge of the suction/discharge hole 2a. This is the time when the control edge 14a is located on the upper side and the control edge 14a is in the forward direction on the low load side It is located on the high load side and on the rear end side in the forward movement direction. Therefore, The firing end time is earlier when the load is low, and becomes later when the load is high.

[0018] As mentioned above, the injection start and end timings are earlier when the load is low, and when the load is high In this embodiment, as shown in Fig. 1(B), the speed becomes slower at low load. Fuel injection is set to occur in range A of the low speed range, and at high load. is set so that fuel injection is performed in range B of the high speed range. Range A is Since the engine is in a low speed range, the fuel injection rate under low load is low regardless of the rotation speed. on the other hand Since range B is a high speed range, the fuel injection rate under high load is always high. Note that when the load is low, the injection rate is low and there is a gap between the upper lead 12 and the lower lead 14. Since the gap is narrow, the amount of fuel injected is small. Of course, when the load is high, the injection rate is high and Since the distance between the upper lead 12 and the lower lead 14 is wide, the fuel injection amount is increased.

[0019] This invention is not limited to the above-mentioned embodiments, but within the scope of the invention. It can be changed as appropriate in the box.

[0020] For example, in the above embodiment, the control edge 12a of the upper lead 12 is rotated at a certain angle. Although it is shown as being inclined, it may also be formed as shown in FIGS. 3 to 6. The one shown in FIG. 3 increases the inclination angle of the control edge 22a of the upper lead 22 at a low load. It is smaller on the high load side. Of course, on the contrary, the inclination angle should be set to the low load side. It may be small on the high load side and large on the high load side. What is shown in FIG. The inclination angle of the goen 32a is reduced in the low load range, increased in the medium load range, and increased in the high load range. It was set to zero. What is shown in FIG. 5 is the slope of the control edge 42a of the upper lead 42. The curved shape is such that the angle gradually decreases from the low load side to the high load side. It was formed in 6, the control edge 52a of the upper lead 52 is The control edge 52a is formed in the shape of the plunger 6 on the high load side. It extends along one circumference toward the low load side, and from there along the axis of the plunger 6. It extends to the tip and is aligned with the tip of the plunger 6 on the low load side. death Therefore, the upper lead 52 is formally formed only on the low load side. ing.

[0021] Of course, the control edge 14a of the lower lead 14 can also be changed as appropriate. however In either case, the fuel injection amount is small on the low load side and large on the high load side. , the distance between the upper lead 12 and the lower lead 14 is narrower on the low load side and wider on the high load side. There is a need.

[0022] Furthermore, the lift speed characteristics of the cam portion 11 are also limited to the above-mentioned lift speed characteristics. 7 to 10 may be adopted instead. Shown in Figure 7 This is the constant lift speed part in the low speed range of the lift speed characteristics shown in Figure 1 (B). is changed so that the lift speed gradually decreases as the cam angle increases. It is. What is shown in FIG. 8 is the lift speed of FIG. 1(B), contrary to what is shown in FIG. The constant portion is changed so that the lift speed gradually increases. What is shown in Figure 9 is shown in Figure 1(B), where the lift speed is higher than that at the front end of the constant lift speed part. This is the part where the speed is slightly faster. What is shown in Figure 10 is the lift speed in the low speed range. The degree is gradually increased.

[0023]

[Effect of the idea]

As explained above, according to the fuel injection pump of this invention, the outer circumference of the plunger The front end and the middle part of the surface are arranged from the low load side to the high load side in the forward direction. to form an upper lead and a lower lead extending in the circumferential direction, and these upper leads and Each control edge adjacent to the lower lead in the axial direction of the plunger is It is located on the tip side in the forward movement direction of the plunger, and on the rear end side on the high load side. This is because the spacing between these control edges is narrower on the low load side and wider on the high load side. , low injection rate not only at low speeds and low loads such as idling, but also at high speeds and low loads. The effect is that it is possible to realize the following.

[Brief explanation of drawings]

FIG. 1 (A) is a side view showing an enlarged tip of a plunger used in an embodiment of the invention;
(B) is a diagram showing the lift speed characteristics of the cam.

FIG. 2 is a longitudinal sectional view showing an embodiment of the invention.

FIG. 3 is a side view showing an enlarged tip of the plunger according to the invention.

FIG. 4 is a side view showing an enlarged tip of the plunger according to the invention.

FIG. 5 is a side view showing an enlarged tip of the plunger according to the invention.

FIG. 6 is a side view showing an enlarged tip of the plunger according to the invention.

FIG. 7 is a diagram showing lift speed characteristics of the cam according to the invention.

FIG. 8 is a diagram showing lift speed characteristics of the cam according to the invention.

FIG. 9 is a diagram showing lift speed characteristics of the cam according to the invention.

FIG. 10 is a diagram showing lift speed characteristics of the cam according to the invention.

[Explanation of symbols]

2a Suction and exhaust hole 6 Plunger 7 Fuel pressurization chamber 11 Cam part (cam) 12 Upper lead 12a Control edge 14 Lower lead 14a Control edge 15 Control sleeve 16 Control rod 22 Upper lead 22a Control edge 32 Upper lead 32a Control edge 42 Upper lead 42a Control edge 52 Upper lead 52a control edge

Claims (1)

[Scope of utility model registration request] Claim 1: A plunger which is caused to reciprocate by a cam, and which pressurizes the fuel in the fuel pressurizing chamber when its outer circumferential surface covers the suction and exhaust hole opening into the fuel pressurizing chamber during forward movement, and the plunger is rotatably displaced. , the location on the outer circumferential surface of the plunger facing the suction/exhaust hole is changed depending on whether the engine is under low load or high load. The cam has a low speed range in the first half where the lift speed is slow, and a high speed range in the second half where the lift speed decreases after reaching the maximum speed from the low speed range. In a fuel injection pump using a cam, the outer circumferential surface of the plunger has an upper lead and a lower lead extending circumferentially from the low load side to the high load side at the tip and middle part in the forward movement direction. The control edges of the upper lead and the lower lead that are adjacent to each other in the axial direction of the plunger are
It is characterized by being located at the tip side in the forward movement direction of the plunger on the low load side, and at the rear end side on the high load side, and the interval between these control edges is narrow on the low load side and wide on the high load side. fuel injection pump.