JP2013155682A - Fuel supply pump and fuel supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply sufficient fuel to a compression chamber of a high pressure pump even in the case the rotational frequency of an internal combustion engine is low, in the fuel supply pump having a low pressure feed pump driven so as to synchronize with the internal combustion engine.SOLUTION: A fuel supply pump includes a throttle 14 throttling a flow of fuel in a lubricating channel 13, and a channel 47 of the fuel is divided into five channels such that the fuel flows parallel in the throttle 14. Thereby, the throttle 14 can sufficiently throttle the flow of the fuel in the lubricating channel 13, even though a flow rate of the fuel discharged from a low pressure feed pump is low, because a flow channel resistance of the throttle 14 becomes high. Consequently, the sufficient fuel can be supplied to the compression chamber of a high pressure pump even in the case the rotational frequency of an internal combustion engine is low and the flow rate of the fuel discharged from the low pressure feed pump is low.

Description

  The present invention mainly relates to a fuel supply pump that pressurizes and discharges fuel, and more particularly to a fuel supply pump that supplies high-pressure fuel to an internal combustion engine via a common rail.

  Conventionally, in the fuel supply pump, the high pressure pump that pressurizes the fuel and supplies it to the internal combustion engine, the low pressure feed pump that sucks the fuel from the fuel tank and discharges it to the high pressure pump, and the low pressure feed pump. It is known that a part of the fuel is provided with a lubrication path that supplies a part of the fuel between members that are in sliding contact with each other in a high-pressure pump, and a throttle that is provided in the lubrication path and restricts the flow of fuel in the lubrication path. A considerable amount of fuel is sucked and pressurized to a high pressure state of several hundred MPa and supplied to the internal combustion engine via a common rail.

Incidentally, some conventional low-pressure feed pumps employ a gear pump system that is driven to rotate in synchronization with an internal combustion engine. When the low-pressure feed pump is driven to synchronize with the internal combustion engine, the following problems are regarded as problems.
That is, when the rotational speed of the internal combustion engine is low, the flow rate of the fuel discharged from the low pressure feed pump becomes small, so the throttle provided in the lubrication path does not function sufficiently, and the small flow rate discharged from the low pressure feed pump is low. There is a risk that the fuel will flow too much into the lubrication path.

  As a result, when the rotational speed of the internal combustion engine is low, sufficient fuel is not supplied to the pressurizing chamber of the high-pressure pump, and the amount of fuel discharged from the fuel supply pump becomes insufficient with respect to the required amount. There is a risk of causing various problems in the control.

In Patent Document 1, when the rotational speed of the internal combustion engine is low, the discharge side of the low-pressure feed pump is mechanically moved to the pressurizing chamber of the high-pressure pump until the fuel pressure on the discharge side of the low-pressure feed pump is sufficiently increased. An arrangement for closing is disclosed.
However, the configuration of Patent Document 1 is conceived in order to ensure the amount of fuel supplied to the lubrication path, and the amount of supply to the pressurizing chamber is reduced. In addition, the structure itself requires a unique valve structure, and there is a high risk of cost increase.

JP 2003-139209 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel supply pump including a low-pressure feed pump that is driven so as to synchronize with the internal combustion engine. Even in such a case, it is to be able to supply sufficient fuel to the pressurizing chamber of the high-pressure pump.

[Means of Claim 1]
According to the first aspect of the present invention, the fuel supply pump is driven in synchronism with the high-pressure pump that pressurizes the fuel and supplies it to the internal combustion engine, and sucks the fuel from the fuel tank and discharges it to the high-pressure pump. The low-pressure feed pump to be supplied and a part of the fuel discharged from the low-pressure feed pump are supplied between members that are in sliding contact with each other in the high-pressure pump, separately from the pressurizing chamber for pressurizing the fuel in the high-pressure pump. The lubrication path and a fuel flow in the lubrication path are throttled, and the throttle is provided with a plurality of fuel paths divided so that the fuel flows in parallel.

  As a result, the restriction formed by a plurality of passages has higher flow resistance than the restriction formed by a single passage having the same cross-sectional area as the total cross-sectional area of the plurality of passages. For this reason, by dividing the single passage into multiple passages and increasing the flow resistance of the throttle, even when the flow rate of fuel discharged from the low-pressure feed pump is small, the flow of fuel in the lubrication passage is ensured. Can be squeezed. As a result, even when the rotational speed of the internal combustion engine is low and the flow rate of fuel discharged from the low pressure feed pump is small, sufficient fuel can be supplied to the pressurizing chamber of the high pressure pump.

  When the internal combustion engine speed is high and the flow rate of fuel discharged from the low-pressure feed pump is large, the flow rate of fuel passing through the throttle depends on the total cross-sectional area of the passage and does not depend on the flow path resistance. . Therefore, even when the throttle is formed by a plurality of passages and the flow resistance is increased, for example, when the rotational speed of the internal combustion engine is high by setting the total cross-sectional area of the passages so that insufficient lubrication does not occur. It is possible to prevent problems such as insufficient lubrication.

[Means of claim 2]
According to the means of claim 2, the throttle is provided by directly drilling a plurality of passages in the metal body provided with the lubrication path.
Thereby, the fuel supply pump which has the effect of Claim 1 can be manufactured, without adding components newly.

[Means of claim 3]
According to the third aspect of the present invention, the throttle is formed by piercing a plurality of passages in a member separate from the metal body provided with the lubrication path, and attaching the members pierced by the plurality of passages to the metal body. Is provided.
Thereby, the drilling process for providing the channel | path which functions as an aperture_diaphragm | restriction can be given to the member separate from a metal body. For this reason, since it is only necessary to pay consideration to the separate member for the drilling process, it is possible to reduce the complexity of setting the aperture.

[Means of claim 4]
According to the means of claim 4, the fuel supply device accumulates the fuel supply pump according to any one of claims 1 to 3 and the fuel supplied from the fuel supply pump in a high pressure state. A pressure accumulating vessel and a fuel injection valve that distributes high-pressure fuel from the pressure accumulating vessel and injects the distributed fuel directly into the combustion chamber of the internal combustion engine.

1 is an overall configuration diagram of a fuel supply device (Example 1). FIG. (Example 1) which is sectional drawing of a fuel supply pump. (A) is a sectional view showing a diaphragm, (b) is a sectional view taken along line AA of (a), (c) is a sectional view showing a virtual diaphragm formed by a single passage, (D) is BB sectional drawing of (c) (Example 1). (A) is sectional drawing which shows an aperture stop, (b) is a side view of an aperture forming member, (c) is CC sectional drawing of (b), (d) is D of (b). (Example 2) which is -D sectional drawing.

  The fuel supply pump according to the first embodiment is a high-pressure pump that pressurizes fuel and supplies it to the internal combustion engine, and a low-pressure pump that is driven to synchronize with the internal combustion engine and that sucks fuel from the fuel tank and discharges and supplies the fuel to the high-pressure pump. A lubrication path for supplying a feed pump and a part of the fuel discharged from the low-pressure feed pump between members that are in sliding contact with each other in the high-pressure pump, apart from a pressurizing chamber for pressurizing the fuel in the high-pressure pump, and lubrication The fuel flow in the passage is restricted, and the fuel passage includes a restriction in which the fuel passage is divided into a plurality of passages so that the fuel flows in parallel.

Further, the restriction is provided by directly drilling a plurality of passages in the metal body provided with the lubrication path.
Furthermore, the fuel supply apparatus including the fuel supply pump according to the first embodiment is configured to store the fuel supplied from the fuel supply pump in a high pressure state, and to distribute the high pressure fuel from the pressure storage container. A fuel injection valve for direct injection is provided in the combustion chamber of the engine.

  According to the fuel supply pump of the second embodiment, the throttle is provided with a plurality of passages in a member separate from the metal body provided with the lubrication path, and the member having the plurality of passages is attached to the metal body. Is provided.

[Configuration of Example 1]
The structure of the fuel supply pump 1 of Example 1 is demonstrated using FIGS. 1-3.
The fuel supply pump 1 pressurizes and discharges fuel to be supplied to an internal combustion engine (not shown) of the vehicle, for example, and supplies the fuel to the internal combustion engine via a common rail 2 as a pressure accumulation container, for example. A part of the accumulator fuel supply device 3 is configured (see FIG. 1).

  That is, the fuel supply device 3 sucks fuel corresponding to atmospheric pressure from the fuel tank 4 and pressurizes and discharges the fuel pressurized to a high pressure state of several hundred MPa, and the fuel discharged from the fuel supply pump 1 at a high pressure. A common rail 2 for accumulating pressure in the state, an injector 5 serving as a fuel injection valve for distributing high-pressure fuel from the common rail 2 and directly injecting the distributed fuel into a combustion chamber (not shown) of the internal combustion engine; An electronic control unit (hereinafter referred to as ECU 6) for controlling operations of the supply pump 1, the injector 5, and the like is provided.

  Here, the ECU 6 receives detection signals from a rail pressure sensor 7 that detects the pressure of fuel accumulated in the common rail 2 (hereinafter referred to as a common rail pressure) and other various sensors that detect the operating state of the internal combustion engine. Entered. The ECU 6 performs arithmetic processing for controlling the operation of the fuel supply pump 1 and the injector 5 based on the input detection signal, and issues a command to the fuel supply pump 1 and the injector 5 according to the calculation result. give.

In the fuel supply device 3, a fuel filter 8 is incorporated in a fuel flow path connecting the fuel tank 4 and the fuel supply pump 1, and the fuel supply pump 1 is a fuel from which foreign matter has been removed by the fuel filter 8. Inhale.
Further, the injector 5 drives the valve body to close or open the valve body by, for example, applying a back pressure to the valve body (not shown) with fuel received from the common rail 2 and increasing or decreasing the back pressure. It has a well-known structure. Then, the fuel that has flowed out of the injector 5 as the back pressure is reduced returns to the fuel tank 4.

  The fuel supply pump 1 is discharged from a high-pressure pump 11 that pressurizes and discharges fuel, a low-pressure feed pump 12 that sucks fuel from the fuel tank 4 and discharges and supplies the fuel to the high-pressure pump 11, and a low-pressure feed pump 12. A lubrication path 13 for supplying a part of the fuel between members in sliding contact with each other in the high-pressure pump 11 and a throttle 14 for restricting the flow of fuel in the lubrication path 13 are provided.

  The high pressure pump 11 sucks the fuel discharged from the low pressure feed pump 12 through the metering valve 16 into the pressurizing chamber 17, pressurizes the sucked fuel in the pressurizing chamber 17, and discharges the fuel toward the common rail 2. And is driven by a cam mechanism 18.

  The metering valve 16 has its valve opening controlled by the ECU 6 according to the common rail pressure, and the fuel discharged from the low pressure feed pump 12 is metered by the metering valve 16 and then into the pressurizing chamber 17. Inhaled. That is, the metering valve 16 increases or decreases the amount of fuel sucked into the pressurizing chamber 17 according to the common rail pressure.

  The pressurizing chamber 17 is driven by the cam mechanism 18 to linearly reciprocate a plunger 20, a cylinder head 22 having a sliding hole 21 that slidably supports and accommodates the plunger 20, and the pressurizing chamber 17. It is partitioned and formed by a suction-side check valve 23 or the like that intermittently sucks fuel (hereinafter, the axial direction of the plunger 20 and the sliding hole 21 is referred to as a first axial direction). That is, the pressurizing chamber 17 is formed by slidably accommodating the plunger 20 in the sliding hole 21 and sealing the other end side of the sliding hole 21 in the first axial direction by the suction side check valve 23. ing. The pressurizing chamber 17 expands when the plunger 20 moves to one end side in the first axial direction, and shrinks when the plunger 20 moves to the other end side in the first axial direction.

Further, the cylinder head 22 is provided with a discharge-side flow path of the pressurizing chamber 17, and a discharge-side check valve 24 for intermittently discharging fuel from the pressurizing chamber 17 is accommodated in the discharge-side flow path. Has been. The flow path on the downstream side of the discharge side check valve 24 is provided in a member different from the cylinder head 22.
Furthermore, one end of the plunger 20 protrudes from the sliding hole 21 to one end side in the first axial direction. A plunger head 25 having a diameter larger than that of the plunger 20 is provided at one end of the protruding plunger 20 and integrated with the plunger 20.

  The cam mechanism 18 is rotationally driven by an internal combustion engine and has the following configuration. That is, the cam mechanism 18 is rotationally driven by the internal combustion engine, the cam 27 is eccentrically integrated with the shaft 27, and is driven to revolve around the axis of the shaft 27 by the rotation of the shaft 27. 28 is housed on the inner peripheral side, and has a cam ring 29 that is driven to revolve without changing its attitude by revolving the cam 28 (hereinafter, the axial direction of the shaft 27 is referred to as a second axial direction).

  The shaft 27 is rotatably supported by the housing 31 via journals 30a and 30b. Here, the housing 31 has a bearing cover 32 that supports the shaft 27 on the other end side with respect to the second axial direction, and a housing body 33 that supports the shaft 27 on one end side, and the journals 30a and 30b are respectively The bearing cover 32 and the housing body 33 are accommodated.

A gear member (not shown) is fastened to the other end of the shaft 27, and torque is transmitted from the internal combustion engine to the shaft 27 via the gear member.
A low pressure feed pump 12 is provided at one end of the shaft 27, and the low pressure feed pump 12 is directly driven to rotate by the shaft 27.

The cam 28 is provided between a portion of the shaft 27 supported by the bearing cover 32 via the journal 30a and a portion supported by the housing body 33 via the journal 30b. And the like are accommodated in the cam chamber 35.
Here, the cam chamber 35 is formed by the cylinder head 22, the bearing cover 32, the housing body 33, and the like. A part of the fuel discharged from the low pressure feed pump 12 is supplied to the cam chamber 35 through the lubrication path 13. The cylinder head 22 is made of iron, and the bearing cover 32 and the housing body 33 are made of aluminum.

  The cam ring 29 is supported on the outer peripheral side of the cam 28 via the bush 36 and receives sliding contact of the plunger head 25 as the cam 28 revolves. That is, the cam ring 29 has a contact surface 37 that is perpendicular to the first axial direction and receives the contact of the plunger head 25, and the plunger head 25 slides on the contact surface 37 according to the revolution of the cam 28. While moving, it reciprocates relatively in a third direction perpendicular to both the first and second axial directions and parallel to the contact surface 37.

  In addition, two contact surfaces 37 are provided, for example, so that the two plunger heads 25 can contact with each other with an interval of 180 ° around the axis of the shaft 27. Two shafts are formed around the axis of the shaft 27 so as to be spaced apart at an interval of 180 °.

Here, a coil spring 38 extending and contracting in the first axial direction is set between the cylinder head 22 and the plunger head 25, and the plunger head 25 is attached to one end side in the first axial direction by the coil spring 38. It is urged and always contacts the contact surface 37. Further, since the cam ring 29 revolves without changing its posture, the contact surface 37 also revolves without changing its posture, so that the plunger head 25 moves in the first axial direction while sliding on the contact surface 37. While reciprocating, it reciprocates in the third direction relative to the contact surface 37.
A thrust washer 39 is disposed at both ends of the cam 28 and the cam ring 29 in the second axial direction.

  The low-pressure feed pump 12 sucks and discharges fuel by a gear pump system, and is driven to synchronize with the internal combustion engine. That is, the low-pressure feed pump 12 includes a cam 27 that is configured to be rotated by an internal combustion engine, an external gear 41 that is externally fitted to one end of the shaft 27 and is driven to rotate by the shaft 27, and an external gear. An internal gear 42 that rotates in mesh with the external gear 41 is provided on the outer peripheral side of the gear 41, and a fuel chamber 43 is formed by the external teeth and the internal teeth.

The low pressure feed pump 12 sucks fuel from the fuel tank 4 into the fuel chamber 43 by rotating the external teeth and internal gears 41 and 42 and repeatedly expanding and contracting the fuel chamber 43. To the high pressure pump 11.
The fuel discharge pressure by the low-pressure feed pump 12 is regulated by the regulator valve 44, and the fuel that has passed through the regulator valve 44 when the discharge pressure is excessive returns to the suction side of the low-pressure feed pump 12.

  With the above configuration, in the fuel supply pump 1, when the plunger 20 moves to one end side in the first axial direction due to the revolution of the cam 28 and the pressurizing chamber 17 expands, the fuel pressure in the pressurizing chamber 17 is reduced and discharged. The side check valve 24 is closed and the suction side check valve 23 is opened, and the metered fuel is sucked into the pressurizing chamber 17. Further, when the plunger 20 moves to the other end side in the first axial direction and the pressurizing chamber 17 is contracted, the fuel pressure in the pressurizing chamber 17 rises, the suction side check valve 23 is closed, and the discharge side is reversed. The stop valve 24 is opened, and the pressurized fuel is discharged from the pressurizing chamber 17 toward the common rail 2.

The lubrication path 13 is a flow path through which a part of the fuel discharged from the low-pressure feed pump 12 flows, and is branched from the fuel flow path toward the metering valve 16 and the pressurizing chamber 17 and travels toward the cam chamber 35. It is a flow path.
Here, various sliding contact structures are formed in the cam chamber 35 such as sliding contact between the plunger head 25 and the cam ring 29 and sliding contact between the cam 28 and the cam ring 29 via the bush 36. The fuel supplied to the cam chamber 35 through the lubrication path 13 is supplied between the members forming the sliding contact structure to form an oil film, and functions as lubricating oil. The lubrication path 13 is provided in the housing body 33. Further, the fuel supplied to the cam chamber 35 returns to the fuel tank 4 through the check valve 45.

  The restrictor 14 restricts the flow of fuel in the lubrication path 13 and restricts the fuel discharged from the low pressure feed pump 12 from flowing excessively toward the cam chamber 35. In addition, in the throttle 14, the fuel passage 47 is divided into, for example, five so that the fuel flows in parallel (see FIGS. 3A and 3B). (Referred to as passages 47a, 47b, 47c, 47d, 47e). Further, the diaphragm 14 is provided by directly drilling five passages 47 a to 47 e in the housing main body 33.

  Here, the cross-sectional area of each of the passages 47a to 47e is such that the fuel discharged from the low pressure feed pump 12 is cam chamber when the rotational speed of the internal combustion engine is low and the flow rate of the fuel discharged from the low pressure feed pump 12 is small. It is set to a size that can reliably restrict excessive flow toward 35.

  That is, the throttle 14 formed by the five passages 47a to 47e has a single passage 48 having the same cross-sectional area as the total cross-sectional area of the passages 47a to 47e (see FIGS. 3C and 3D). The flow path resistance is higher than that of the restriction 14 formed by the above. For this reason, even if the flow rate of the fuel discharged from the low-pressure feed pump 12 is small, the single passage 48 is divided into five passages 47a to 47e to increase the flow path resistance of the throttle 14, so that lubrication is ensured. The fuel flow in the passage 13 can be reduced.

  When the flow rate of the fuel discharged from the low pressure feed pump 12 is large, the flow rate of the fuel passing through the throttle 14 depends on the total sectional area of the passages 47a to 47e and does not depend on the flow path resistance. Therefore, even if the throttle 14 is formed by five passages 47a to 47e to increase the flow resistance, for example, by setting the total cross-sectional area of the passages 47a to 47e so that insufficient lubrication does not occur, It is possible to prevent problems such as insufficient lubrication from occurring when the rotational speed of the internal combustion engine is high.

[Effect of Example 1]
The fuel supply pump 1 according to the first embodiment includes a throttle 14 that restricts the flow of fuel in the lubrication path 13, and the throttle 14 has five fuel passages 47 that allow fuel to flow in parallel.
As a result, the flow path resistance of the throttle 14 is increased, so that the throttle 14 can sufficiently throttle the fuel flow in the lubrication path 13 even when the flow rate of the fuel discharged from the low-pressure feed pump 12 is small. For this reason, even when the rotational speed of the internal combustion engine is low and the flow rate of the fuel discharged from the low pressure feed pump 12 is small, sufficient fuel can be supplied to the pressurizing chamber 17 of the high pressure pump 11.

The diaphragm 14 is provided by directly drilling five passages 47 a to 47 e in the housing main body 33.
Thereby, the fuel supply pump 1 which can acquire said effect can be manufactured, without adding components newly.

[Example 2]
According to the fuel supply pump 1 of the second embodiment, as shown in FIG. 4, the throttle 14 has four small passages 51 a, 51 b, 51 c, 51 d in the throttle forming member 50, which is a separate body from the housing body 33. At the same time, the diaphragm forming member 50 having the small passages 51 a to 51 d is provided in the housing body 33. The small passages 51a to 51d substantially function as the throttle 14. That is, the small passages 51 a to 51 d are the passages 47 that form the diaphragm 14.

  Here, the diaphragm forming member 50 is screwed to the housing main body 33, has a head portion 52 and a shaft portion 53, and has a large passage 54 penetrating the head portion 52 and the shaft portion 53. Here, the large passage 54 opens to the outside of the member at the head 52 and is closed near the tip of the shaft portion 53. Further, the small passages 51a to 51d are provided radially at equal angular intervals so as to communicate the large passage 54 and the outside of the member in the vicinity of the distal end of the large passage 54. The diaphragm forming member 50 is attached to the housing main body 33 by being screwed into a female screw hole provided in the middle of the lubrication path 13.

  Accordingly, the hole forming process for providing the small passages 51a to 51d can be performed on the drawing member 50 which is separate from the housing main body 33. Therefore, the complexity of setting the aperture 14 can be reduced.

[Modification]
The mode of the fuel supply pump 1 is not limited to the first and second embodiments, and various modifications can be considered.
For example, according to the fuel supply pumps 1 of the first and second embodiments, the two plungers 20 are provided and the two pressure chambers 17 are formed around the shaft 27 at intervals of 180 °. The three pressurizing chambers 17 may be formed around the shaft 27 at intervals of 120 °.

Further, according to the fuel supply pump 1 of the first and second embodiments, the metering valve 16 is incorporated on the suction side of the pressurizing chamber 17, and the amount of fuel sucked into the pressurizing chamber 17 is metered. However, the metering valve 16 may be incorporated on the discharge side of the pressurizing chamber 17 and the amount of fuel discharged from the pressurizing chamber 17 may be metered.
Furthermore, the number of the passages 47 forming the diaphragm 14 is not limited to four or five as long as it is a plurality of two or more.

DESCRIPTION OF SYMBOLS 1 Fuel supply pump 4 Fuel tank 11 High pressure pump 12 Low pressure feed pump 13 Lubrication path 14 Restriction 17 Pressurization chamber 47 Path

Claims (4)

A high pressure pump (11) for pressurizing the fuel and supplying it to the internal combustion engine;
A low-pressure feed pump (12) that is driven in synchronism with the internal combustion engine, sucks fuel from a fuel tank (4), and discharges and supplies the fuel to the high-pressure pump (11);
A part of the fuel discharged from the low-pressure feed pump (12) is brought into sliding contact with the high-pressure pump (11) separately from the pressurizing chamber (17) for pressurizing the fuel in the high-pressure pump (11). A lubrication path (13) for supplying between mating members;
A fuel supply pump (1) that restricts the flow of fuel in the lubrication path (13) and includes a restriction (14) in which a fuel passage (47) is divided into a plurality of lines so that the fuel flows in parallel. The fuel supply pump (1) according to claim 1,
The fuel supply pump, wherein the throttle (14) is provided by directly drilling a plurality of passages (47a to 47e) in a metal body (33) provided with the lubrication path (13). (1). The fuel supply pump (1) according to claim 1,
The throttle (14) has a plurality of passages (51a to 51d) formed in a member (50) separate from the metal body (33) provided with the lubrication passage (13), and the plurality of passages ( The fuel supply pump (1) is provided by mounting a member (50) having holes 51a to 51d) on the metal body (33). A fuel supply pump (1) according to any one of claims 1 to 3,
An accumulator (2) for accumulating fuel supplied from the fuel supply pump (1) in a high-pressure state;
A fuel supply device (3) provided with a fuel injection valve (5) that distributes high-pressure fuel from the pressure accumulating vessel (2) and injects the distributed fuel directly into the combustion chamber of the internal combustion engine.

Images