JP2600877B2 - Inner cam type distribution type fuel injection pump - Google Patents

Description

Description: BACKGROUND OF THE INVENTION (Industrial application field) The present invention relates to an inner-cam type distribution type fuel injection pump for supplying fuel to a diesel engine or the like under pressure, and more particularly, to a roller that slides on an inner peripheral surface of the inner cam. The present invention relates to a fuel injection pump in which lubricating oil easily enters a gap with a roller shoe.

(Prior Art) An inner cam type distribution type fuel injection pump is configured to displace fuel in a plunger chamber pressurized by a cam lift of a plunger when a fuel port of a rotor that slides and rotates in a cylinder communicates with a discharge port of the cylinder. The fuel is supplied from a delivery port to a diesel engine through a delivery port of a cylinder, a fuel passage, and the like from a delivery valve (JP-A-59-145359).
Issue).

Then, as shown in FIG. 12, for example, the pumping mechanism of the distribution type fuel injection pump has a rotor 13 for distributing fuel, a through hole 35 opened in the rotor radial direction, and slidably fitted in the through hole 35. The plungers 36 to be combined, the plunger chamber 14 defined by the inner end faces of the plungers 36, the roller shoes 38 abutting on the other end faces of the plungers 36, and the roller guide grooves 38a of the roller shoes 38 are rotatably provided. Roller 39,
It is composed of an inner cam 40 with which the roller 39 contacts.

The roller 39 reciprocates the plunger 36 via the roller shoe 38 in accordance with the inner peripheral cam shape of the inner cam 40 with the rotation of the rotor 13, so that the fuel is sucked into the plunger chamber 14 and fed.

(Problems to be Solved by the Invention) In such an inner cam type distribution type fuel injection pump,
As shown in FIG. 12, the roller 39 is
, And makes sliding contact with the roller guide groove 38a. In this case, the roller 39 and the inner cam 40
There is no problem because the lubrication oil is lubricated by the surrounding lubricating oil.

However, the gap between the roller 39 and the roller shoe 38 is small, and when the rotor 13 rotates in the direction indicated by the arrow A in FIG. 13 with respect to the inner cam 40, the roller 39 rotates in the direction indicated by the arrow B. Since the tip portion has a cutting edge shape, the lubricating oil on the outer periphery of the roller is not sufficiently caught in the roller guide groove 38a, and the oil film formation between the roller 39 and the roller shoe 38 is insufficient, so that the roller 39 and the roller shoe 38 or the roller 39 There is a problem that seizure and abrasion easily occur with the inner cam 40.

The present invention has been made in order to solve such problems, and promotes the formation of an oil film so that lubricating oil is easily guided to a roller guide groove of a roller shoe, suppresses seizure, abrasion, and the like, and improves durability. It is an object of the present invention to provide an inner cam type distribution type fuel injection pump in which the pressure is improved.

(Means for Solving the Problems) For this purpose, a distribution type fuel injection pump according to the present invention includes a rotor having a distribution portion that slidably rotates in a cylinder and distributes fuel, and a position surrounding a pressurizing portion of the rotor. An inner cam, a roller contacting a cam surface of the inner cam, a roller shoe rotatably supported by a roller guide groove, and a roller shoe formed on an outer peripheral surface of a pressing portion of the rotor, the roller shoe having a diameter. The roller is pressed against the cam surface of the inner cam via the roller shoe, and the inner cam is formed in a through hole formed in a radial direction of a pressing portion of the rotor. A plunger that reciprocates according to the cam surface of the plunger; a fuel pressurizing chamber defined by the inner end face of the plunger and the inner wall surface of the through hole; A metering member for controlling the amount of fuel to be supplied, and pressurizing the fuel in the fuel pressurizing chamber by sliding the plunger, and forcing a predetermined fuel injection amount to the engine via a distributor of the rotor. In the pump, an oil introduction groove is provided at least at a rear end of the roller guide groove of the roller shoe in the rotor rotation direction along the rotor axial direction.

(Operation) According to the distribution type fuel injection pump of the present invention, the lubricating oil around the roller that comes into rolling contact with the inner peripheral surface of the inner cam with the rotation of the rotor is actively drawn into the roller guide groove from the oil introduction groove. The formation of an oil film on the guide groove surface is promoted, and seizure between the roller and the roller shoe and between the roller and the inner cam is prevented, and wear is suppressed.

(Example) An example of the present invention will be described with reference to the drawings.

FIG. 2 shows a schematic configuration of an inner-cam type distribution type fuel injection pump according to a first embodiment of the present invention.

The distribution type fuel injection pump 1 has a gallery (low fuel pressure chamber) 5 which pumps fuel pumped from the fuel tank 3 to the pump low pressure side passage 6 by the feed pump 2 via the pump high pressure side passage 4.
High-pressure fuel whose injection timing and injection amount are adjusted as described later is pumped from the delivery valve 7 to the injection nozzle of the diesel engine.

The inside of the fuel injection pump 1 has a cylindrical cylinder 12 built in a pump housing 11, a rotor 13 rotatably fitted to an inner peripheral surface of the cylinder 12, and switching a fuel passage.
The rotor 13 includes an electromagnetic spill valve 16 and the like for allowing fuel pressurized by a plunger chamber (fuel pressurizing chamber) 14 to overflow from a fuel passage in the rotor 13.

Inside the cylinder 12, a suction passage 2 for supplying fuel from the gallery 5 to the plunger chamber 14 via the communication passage 34 is provided.
1. A discharge passage 22 for pumping the fuel pressurized in the plunger chamber 14 to the delivery valve 7, and an overflow for releasing the fuel from the plunger chamber (fuel pressurizing chamber) 14 to the gallery 5 to adjust the fuel injection amount. Passages 23 are provided, and these passages 21, 22, 23 are respectively opened on the outer peripheral surface of the rotor small diameter portion 13a that slides on the cylinder inner peripheral wall surface 12a.

The plunger chamber 1 is provided in the rotor small diameter portion 13a for distributing fuel.
A suction port 31 for introducing the fuel supplied to the intake passage 4 from the suction passage 21, and a high-pressure fuel pressurized in the plunger chamber 14 is supplied to the discharge passage 31.
A discharge port 32 for discharging fuel to an overflow port 22, an overflow port 33 for discharging fuel to an overflow passage 23 for adjusting a fuel injection amount, one end of each of which is connected to each of the ports 31, 32, 33, and the other end of which is a plunger chamber 14.
Are provided respectively with communication paths 34 communicating with each other.

The rotor large-diameter portion 13b as a fuel pressurizing portion having a larger outer diameter than the rotor small-diameter portion 13a is provided with two through holes 35 orthogonal to the radial direction. Four plungers 36 are fitted slidably in the radial direction, and the plunger chamber 14 is interposed between the inner end faces of the plungers 36.
Is formed.

As shown in FIG. 3, a roller shoe 38 for rotatably holding a roller 39 is provided on an outer end surface of the plunger 36 in a radially outward direction.
Are slidably disposed in the shoe guide groove 81 in the radial direction. The inner peripheral surface 40a of the inner cam (inner cam) 40 faces the radially outer direction of the roller 39, and a cam ridge is formed in a circumferential direction of the inner peripheral surface. Plunger 36 urged radially outward by the fuel pressure and centrifugal force of plunger chamber 14
Is connected to the roller 39 via the roller shoe 38 by one end.
Is in contact with the cam surface formed on the inner peripheral surface 40a.

In the fuel suction stroke in which the plunger 36 moves radially outward by the rotation of the rotor 13, the suction passage 21 and the suction port 31 are moved.
Communicate with the suction passage 21 and the suction port during the compression stroke.
31 is arranged to close. Further, the discharge port 32 of the rotor 13 communicates with the discharge passage 22 of the cylinder 12 during a discharge stroke. The discharge passage 22 is connected to the pump housing 11
It is connected to the delivery valve 7 via the passage 57 inside. The delivery valve 7 is connected to a pipe (not shown), and the other end of the pipe is connected to an injection nozzle mounted on a diesel engine.

An electromagnetic spill valve 16 is disposed in a fuel passage downstream of the overflow passage 23, and the electromagnetic spill valve 16 establishes or blocks communication between the overflow passage 23 and the gallery 5. Solenoid spill valve
The drive 16 is controlled based on a signal indicating the operation state of the diesel engine, for example, a signal from an accelerator opening sensor, a signal from a rotation sensor, and the like.

A rotation speed signal detected by a rotation sensor 28 provided at a position facing the pulsar 26 provided in the rotor large-diameter portion 13b is input to a control device 60.The control device 60 changes the engine operation state based on various sensor signals. The required electromagnetic spill valve opening timing is calculated, the valve opening time is converted into a time, and a valve opening signal is sent to the electromagnetic spill valve 16.

When the rotor 13 is rotated by the rotation of the diesel engine, the plunger 36 reciprocates in the radial direction along the cam profile of the inner cam 40 to suck fuel from the gallery 5 into the plunger chamber 14 and a delivery valve from the plunger chamber 14. The pressure feeding process of sending high-pressure fuel to the nozzle via 7 is repeated, and in synchronization with this, the overflow timing is adjusted by the electromagnetic spill valve 16, that is, the fuel injection amount is controlled.

As shown in FIGS. 1 (A), (B), (C), FIGS. 3 and 4, a roller shoe 38 according to a first embodiment of the present invention is a roller shoe which rotatably supports a roller 39. Guide groove 38
An oil introduction groove 38b is provided in the roller axial direction on the rear side in the rotor rotation direction (the direction indicated by the arrow A in FIG. 4). Both ends in the roller axis direction of the oil introduction groove 38b formed by chamfering are
An edge-shaped roller falling-off preventing portion 38c is left. The roller falling-off preventing portion 38c is provided with the roller falling-off preventing portion 3 facing thereto.
The roller 8 sandwiches the outer periphery of the roller 39 and plays a role of preventing the roller 39 from dropping out of the roller guide groove 38a.

Regarding the processing method of the roller shoe 38, for example, a through hole is made in the longitudinal direction of the block material, heat treatment is applied, the sliding surface such as the hole and side surface is polished, unnecessary parts are cut, and oil is introduced by electric discharge machining or the like. A groove 38b is formed. As a result, the formation of an oil film between the roller shoe 38 and the roller 39 is improved, and seizure is prevented and wear is suppressed.

Next, regarding the dimensions of each part of the roller and roller shoe,
A description will be given based on FIG. 5 and FIG. Here, a roller shoe having a shoe longitudinal length L = 20 mm and a guide groove diameter D = 8 mm will be described as an example.

The clearance ΔR between the roller outer peripheral surface and the roller guide groove is
It is preferable that ΔR ≧ 150 μm. This is because, as shown in FIG. 7, when ΔR ≧ 150 μm, the roller easily rolls in the roller guide groove, and when the roller comes into sliding contact from rolling contact, the allowable surface pressure with the inner peripheral surface of the inner cam at the time of sliding contact is reduced. Since it is 5 to 7 times, it is more preferable to make the roller in rolling contact, since stress concentration can be avoided and strength is required.

From the viewpoint of the contact surface pressure shown in FIG. 8, the clearance ΔR
Exceeds 30 μm, the allowable contact surface pressure between the roller and the roller shoe is exceeded. Therefore, the clearance ΔR is set to 30 μm or less unless other dimensions are changed.

However, in this case, there is no range of the clearance ΔR that satisfies both of the above requirements. Therefore, in the present embodiment, an oil introduction groove 38b is formed as an oil introduction groove at the end of the roller guide groove of the roller shoe on the rotor rotation rear side. The oil introduction groove 38b is a place where the surface pressure from the roller 39 does not act. By providing this oil introduction groove, the roller
The contact between the roller shoe 38 and the roller shoe 38 is increased from the sliding contact to the rolling contact. This solves the problem of strength.

The reason why the oil introduction groove 38b is provided in a part of the entire length of the shoe in the axial direction of the shoe is that if the pressing force is not applied between the roller shoe 38 and the roller 39 during the plunger suction stroke, the oil introduction groove 38b is provided in the entire axial length of the shoe. This is because the roller 39 may fall off from the roller guide groove 38a.

In order to prevent the roller 39 from dropping out of the roller guide groove 38a, it is conceivable to increase the height H of the shoe top surface 38e from the center of the roller rotation shaft as shown in FIG. Is too large, as shown in FIG.
Since the shoe top surface 38e interferes with the inner cam inner peripheral surface 40a, the height H cannot be set to 0.7 mm or more with this roller shoe as shown in FIG. Therefore, the height H is set to less than 0.7 mm, and the roller drop-off preventing portion 38c is provided.

The axial length C of the roller falling-off preventing portion 38c is set to a length that does not hinder the formation of an oil film, for example, about L / 10.

The dimension of the vertical height b of the shoe top surface 38e from the connection between the oil introduction groove 38b and the roller guide groove 38a is determined by the oil introduction groove 3
The dimension of the chamfer distance a shown in FIG. 5 and the workability are set so that 8b is connected to the inner peripheral surface of the roller guide groove 38a as slowly as possible in the tangential direction of the inner peripheral surface of the roller guide groove. It is better to decide from. The oil guide groove 38b is set so as to be connected to the inner peripheral surface of the roller guide groove 38a as tangentially as possible because the clearance ΔR is rapidly changed from the roller guide groove 38a to the oil guide groove 38a. This is because it does not have a favorable effect on the formation of the oil film of 38a.

According to the first embodiment, the rotor 13 is
When the roller rotates, as shown in FIG. 4, the surrounding lubricating oil moves from the oil introduction groove 38b to the roller guide groove 38a as the roller 39 rotates.
Positively flows into the roller guide groove 38a, so that the roller 39 can easily roll, and the rolling contact can easily occur from sliding contact, so that the maximum contact surface pressure is reduced, and stress concentration with the inner cam 40 is avoided. Therefore, not only seizure can be prevented, but also durability can be improved.

FIGS. 10 and 11 show the roller shoe shapes of the second and third embodiments of the present invention, respectively.

In the roller shoe 38 of the second embodiment shown in FIG. 10, oil guide grooves 38b and 38f are formed at both front and rear ends of a roller guide groove 38a in the rotor rotation direction. Oil introduction groove
Roller falling-off preventing portions 38c and 38g are formed on both sides of 38b, respectively. In the second embodiment, the roller guide grooves 38a
Since the oil introduction grooves 38b and 38f are formed at both ends of the lubricating oil, the lubricating oil flows well, and the seizure can be more effectively prevented.

The roller shoe 38 of the third embodiment shown in FIG. 11 has oil introduction grooves 38h formed at both ends in the axial direction of the roller, and a roller drop-off preventing portion 38j formed at the central portion in the axial direction. An oil introduction groove 38i is formed at the other end of the groove, and a roller drop-off preventing portion 38k is formed at the center in the axial direction. Also in the third embodiment, seizure prevention and wear suppression are achieved by preventing the rollers from falling off and improving the lubricity, and the durability of the shoes, rollers, inner cams, etc. is improved.

(Effect of the Invention) As described above, according to the distribution type fuel injection pump of the present invention, the oil introduction groove is formed at least at the rear end in the rotor rotation direction of the roller shoe that rotatably supports the roller abutting on the inner cam. Therefore, the formation of an oil film between the shoe and the roller is promoted, the seizure of the roller and the shoe or the roller and the inner cam is reliably prevented by lubrication, cooling, and the like, and the wear of the contact portion is suppressed, and the durability of the inner cam portion is improved. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 shows a roller shoe according to a first embodiment of the present invention, wherein (A) is a plan view, (B) is a side view, and (C).
2 is a cross-sectional view taken along the line CC of FIG. 2A, FIG. 2 is a schematic configuration diagram of an inner cam type distribution type fuel injection pump using the roller shoe shown in FIG. 1, and FIG. 3 is a line III-III in FIG. Sectional view, fourth
FIG. 5 is an explanatory view showing the operation around the roller, FIG. 5 is a view showing the dimensions of the roller and the roller shoe, FIG. 6 is a view showing the dimensions of each part of the roller shoe, and FIG. FIG. 8 shows the contact surface pressure between the roller and the roller shoe as the clearance ΔR.
FIG. 9 is a diagram showing a roller drop limit characteristic, FIG. 10 is a plan view showing a roller shoe of a second embodiment of the present invention, and FIG. 11 is a third diagram of the third embodiment of the present invention. FIG. 12 is a plan view showing a roller shoe of the embodiment, FIG. 12 is a cross-sectional view showing an inner cam mechanism, FIG. 13 is an explanatory view showing the periphery of a roller in a conventional example, and FIG. 14 describes a first embodiment of the present invention. Therefore, it is an explanatory diagram of a comparative example. 1 ... fuel injection pump, 12 ... cylinder, 13 ... rotor, 14 ...
Plunger chamber (fuel pressurizing chamber), 16: electromagnetic spill valve (metering member), 36: plunger, 38: roller shoe, 38a: roller guide groove, 38b: oil introduction groove, 39: roller, 40: inner cam, 40a … Inner cam inner peripheral surface (cam surface).

Claims (1)

(57) [Claims] A rotor having a distribution portion that slides and rotates in a cylinder and distributes fuel; an inner cam provided at a position surrounding a pressurizing portion of the rotor; a roller abutting on a cam surface of the inner cam; A roller shoe rotatably supporting a roller with a roller guide groove; a shoe guide groove formed on an outer peripheral surface of a pressing portion of the rotor to guide the roller shoe slidably in a radial direction; and a cam of the inner cam. A plunger that presses the roller against the surface via the roller shoe and reciprocates in a through hole formed in a radial direction of a pressing portion of the rotor in accordance with the cam surface of the inner cam; A fuel pressurizing chamber defined by an end face and an inner wall surface of the through hole; and a metering member that controls an amount of fuel pumped from the fuel pressurizing chamber through a distributor of the rotor. A distribution type fuel injection pump for pressurizing the fuel in the fuel pressurization chamber by movement and forcing a predetermined amount of fuel injection to an engine via a distribution part of a rotor, wherein at least a rear end of a roller guide groove of the roller shoe in a rotor rotation direction. An inner cam type distribution type fuel injection pump characterized in that an oil introduction groove is provided along a roller axial direction on the inner side.