KR102540496B1 - Pulsating Volume Extensible Type High Pressure Pump - Google Patents

Abstract

The pulsation volume expansion type high-pressure pump 1 of the present invention expands the pulsation volume formed in the piston rod 13 moving together with the piston 6 in the space volume of the fuel reservoir 11, which is the place where the pulsation occurs in the pump housing 2. By compensating with the part 10, it is possible to reduce the pulsation noise while increasing the control precision of the pump by eliminating the cause of pulsation, and it is possible to secure the durability of components through the prevention of cavitation. As the shape expands the volume of the fuel reservoir as the piston descends, performance is improved without increasing the size and weight of the pump, but it has an advantage in price competitiveness because there is no additional processing process.

Description

Pulsating Volume Extensible Type High Pressure Pump

The present invention relates to a high-pressure pump, and more particularly, to a high-pressure pump in which volume reduction, which is a cause of pulsation, is compensated for during the reciprocating motion of a piston.

In general, a high-pressure pump for a vehicle is a pump device that compresses low-pressure fuel in a fuel tank to high-pressure by a required amount and sends it to a fuel rail in order to inject high-pressure fuel into an engine cylinder. In this case, the high-pressure fuel of the fuel rail is supplied to an injector that injects fuel into an engine cylinder to control engine output according to driving conditions.

For example, the high-pressure pump seals the fuel supplied to the compression chamber by an amount calculated through an on-off valve operated by a solenoid inside the pump, and compresses the fuel by a piston moving upward by a cam. The compression pressure becomes higher than that of the fuel rail at the rear end of the discharge part, and the one-way check valve of the discharge part is opened by the force of the pressure difference to discharge high-pressure fuel.

After that, when the pressure in the compression chamber decreases as the piston descends and the check valve closes due to the pressure difference, the solenoid valve opens to receive fuel again, and the process of increasing the pressure of the fuel by repeating the compression stroke of the piston is repeated.

In particular, the high-pressure pump is provided with a pressure damper for reducing pulsation as the vertical reciprocating motion of the piston causes pulsation of internal fuel. In this case, the pulsation occurs due to a volume reduction of the fuel reservoir at the lower end of the piston due to momentary volume compression caused by the descent of the piston during operation of the high-pressure pump.

For example, the pressure damper is a lid-shaped lid that blocks the upper part of the pump housing, a diaphragm located in the damper space where the low-pressure fuel is introduced by being built in an assembly space formed by the lid and connected to a low-pressure fitting, and fuel leaking due to a piston gap It consists of a damper passage that communicates the fuel reservoir at the bottom of the piston where the fuel is collected and the damper space.

Therefore, the pressure damper reduces the momentary volume reduction caused by the pressure applied by the lower end of the piston in the fuel reservoir due to the piston descending during operation of the high-pressure pump by the communication structure between the damper passage and the damper space.

From this, the high-pressure pump can reduce precision degradation of control valves caused by pulsation, deterioration in durability of components due to cavitation, and pulsation noise.

Japanese Patent Publication JP 2018-105274A (2018.07.05)

However, the high-pressure pump reduces the precision of the flow control valve due to internal fuel pulsation, improves the damper structure for high efficiency, and deflects the piston by the cam in an environment where the force in the direction perpendicular to the piston axis continuously acts in the cam rotation direction. It must be able to withstand wear and tear.

In particular, since the piston of the high-pressure pump operates according to the engine speed, the engine speed is in a situation where greater pulsation occurs as the engine speed goes from low RPM (Revolution Per Minute) to high RPM (Revolution Per Minute), which improves the performance of the pressure damper. are demanding

To this end, the pressure damper increases the size and number of damper passages in the high-pressure pump housing along with improving the performance of the damper itself, but the performance improvement of the damper itself is proportional to the damper size, so parts such as housing and lead to accommodate it It has no choice but to grow together, and the expansion of the damper passage or the addition of the passage is a method in which the space of the high-pressure pump housing is limited and the processing process is inevitably increased.

Therefore, improving the pulsation performance of the high-pressure pump is disadvantageous in size/weight/price competitiveness due to the increase in size of parts (ie, housing and lead) of the pressure damper, and also disadvantageous in price competitiveness due to the increase in processing steps.

Therefore, in view of the above, the present invention expands the volume of the fuel reservoir at the bottom of the piston to remove the cause of pulsation through volume reduction compensation, thereby improving pump control precision and securing the durability of component parts. In particular, the piston rod The purpose is to provide a pulsating volume-expanding high-pressure pump that is advantageous in price competitiveness because there is no additional processing process while performance is improved without increasing the size and weight of the pump by expanding the volume of the fuel reservoir according to the piston descent.

The high-pressure pump of the present invention for achieving the above object is a pump housing having a compression chamber in which low-pressure fuel is converted to high-pressure fuel with a reciprocating piston, a fuel reservoir in which leaked fuel from the compression chamber is collected, and the above It is characterized in that a pulsating volume expansion part is included which moves together with the piston and communicates with the space of the fuel reservoir in a state in which the piston is lowered to increase the space volume.

As a preferred embodiment, the pulsating volume expanding portion is formed on a piston rod integrally extended with the piston; In the lowered position of the piston, the piston rod is positioned in a section of the piston rod facing the space of the fuel reservoir.

As a preferred embodiment, the piston rod section forms the pulsating volume expansion part by any one of a groove, a slot and a hole.

As a preferred embodiment, each of the groove and the slot is formed by cutting the outer diameter of the piston rod, the groove is formed in a circular circumferential structure, and the slot is a straight cross section that is left / right symmetrical in the cross section of the piston rod formed into a structure

As a preferred embodiment, the hole consists of a first hole and a second hole drilled in the outer diameter of the piston rod, and the first hole and the second hole intersect each other to form a “+” cross-sectional structure.

In a preferred embodiment, the piston is coupled with a cylinder that guides movement into a cylinder guide area, and the pulsating volume expansion part is covered by the cylinder guide area when the piston moves up, while moving out of the cylinder guide area when moving down. It communicates with the fuel reservoir.

As a preferred embodiment, the fuel reservoir forms a closed space with a seal assembly provided under the pump housing.

As a preferred embodiment, the pump housing is provided with a flow control valve and a discharge valve, the flow control valve adjusts the amount of compressed fuel entering the compression chamber, and the discharge valve discharges the compressed fuel from the compression chamber.

In a preferred embodiment, the pump housing is provided with a damper that reduces pressure fluctuations of the low-pressure fuel in the low-pressure fuel space, and the low-pressure fuel space communicates with the fuel reservoir through a damper passage bored in the pump housing.

The pulsating volume-expanding high-pressure pump of the present invention implements the following actions and effects.

First, it is possible to manufacture a high-pressure pump capable of reducing or blocking generation of pulsation without changing the structure of a pressure damper by compensating for a volume change with a piston structure during the reciprocating motion of the piston. Second, since the piston expands the volume of the fuel reservoir formed under the piston, fuel density can be maintained by preventing cavitation of the fuel reservoir. Third, control precision of the flow control valve is improved through pulsation reduction, and unnecessary loss of driving energy is prevented through optimized fuel supply under operating conditions that change from low RPM to high RPM. Fourth, it is possible to reduce the size of the damper and reduce noise through the reduction of pulsation, thereby reducing the size of the housing and lead and reducing the number of damper passages in the housing, thereby improving costs. Fifth, in an environment where force in the direction perpendicular to the piston axis continuously acts in the cam rotation direction, the volume expansion unit aligns the axis of the piston, The durability of parts is secured by reducing the deformation and side wear of the piston caused by the cam.

1 is a block diagram of a pulsating volume-expanding high-pressure pump according to the present invention, FIG. 2 is a detailed structural diagram of a pulsating volume-expanding unit according to the present invention, and FIG. 4 and 5 are variant examples of the pulsating volume expansion part according to the invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying exemplary drawings, and since these embodiments can be implemented in various different forms by those skilled in the art as an example, the description herein It is not limited to the embodiment of

Referring to FIG. 1 , the high-pressure pump 1 includes a pulsating volume expansion part 10 associated with a piston 6 inside a pump housing 2 .

Specifically, the high-pressure pump 1 includes a pump housing 2, a cylinder 3, and a flow rate control that convert low-pressure fuel into high-pressure fuel by reciprocating motion of the piston 6 by the rotation of the cam 100 at the bottom of the pump. A pulsating volume expansion part (10) consisting of a valve (4), a discharge valve (5), a piston (6), a seal assembly (7) and a damper (8) and compensating for the volume reduction of the fuel reservoir (11) is formed in conjunction with the piston 6.

For example, the pump housing 2 provides an assembly space for pump components, and a compression chamber, which is a fuel compression space, between a low pressure/high pressure flow path for discharging low pressure fuel supplied to a low pressure fitting connecting a pump and a low pressure fuel line to high pressure fuel. form

For example, the flow control valve 4 is a solenoid valve that determines the amount of compressed fuel, and when the discharge valve 5 is opened, the pump's compressed fuel is delivered to the fuel rail, while when closed, the high-pressure fuel flows backward from the fuel rail. it prevents

For example, the cylinder 3 is provided inside the pump housing 2 to guide the reciprocating motion of the piston 6, and fuel leakage occurs in the gap formed with the piston 6 to the fuel reservoir 11. It is discharged. The piston 6 pressurizes the fuel in the compression chamber through reciprocating motion of vertical motion.

For example, the seal assembly 7 seals a lower portion of the piston so that the fuel reservoir 11 for storing leaked fuel between the piston 6 and the cylinder 3 constitutes a low-pressure flow path. To this end, the seal assembly 7 is composed of one sleeve assembled with the pump housing 2, one seal that seals the piston 6, and one sleeve that prevents the piston 6 from escaping.

For example, the damper 8 is composed of two diaphragms sealed by welding after filling with gas and a lid-shaped lead that blocks the upper part of the pump housing, and reduces fluctuations in external pressure through compressed gas inside the diaphragm. In this case, the fluctuation of the external pressure is a pressure fluctuation of the low-pressure fuel supplied to the pump housing 2 through the low-pressure fitting.

For example, the pulsation volume expansion unit 10 reduces or eliminates the pulsation by compensating for the volume reduction of the fuel reservoir 11 formed at the lower end of the pump when the piston descends during the reciprocating motion of the piston 6, so that the high pressure pump 1 pulsates. It acts to be characterized as a volume expansion type high pressure pump.

On the other hand, referring to FIG. 2, the pulsation volume expansion part 10 is made of a groove 15 using a piston rod 13 integral with the piston 6, and the groove 15 is a damper passage 20 It is associated with the fuel reservoir 11 in communication with.

For example, the groove 15 is formed as a stepped section formed by a small-diameter body obtained by concentrically cutting a large-diameter body of the piston rod 13. In this case, the difference in diameter between the large-diameter body and the small-diameter body forms a damper defined volume, and the damper defined volume is variably set to reduce the size of pulsation, which varies depending on the specifications of the high pressure pump 1, to an appropriate level. .

For example, the fuel reservoir 11 is a space in which low-pressure fuel leaked from a gap formed between the cylinder 3 and the piston 6 is collected. Further, the damper passage 20 communicates the low-pressure fuel space on the upper part of the housing in which the damper 8 is built in with the fuel reservoir 11, and one or more damper passages 20 are vertically pierced through the pump housing 2.

Meanwhile, FIG. 3 illustrates a pulsation reducing effect realized through the pulsation volume expansion unit 10 when the high-pressure pump 1 operates.

As an example, referring to the piston lifting state (a), the groove 15 is located in the cylinder guide area, which is the inner space of the cylinder 3, due to the piston rod 13 raised together with the piston 6, thereby sealing the groove ( A) is converted to In this state, as the piston 6 compresses the low-pressure fuel in the compression chamber into high-pressure fuel, some low-pressure fuel in the compression chamber escapes into the fuel reservoir 11 as leaked fuel through the gap between the cylinder 3 and the piston 6. will go out

Next, referring to the piston descending state (b), the groove 15 is formed by the piston rod 13 coming down due to the descending of the piston 6 exiting the cylinder guide area of the cylinder 3, so that the fuel reservoir 11 ) and is converted to groove communication (B).

Then, the fuel reservoir 11 gradually faces the groove 15 through the piston rod 13 coming down, and the groove 15 is a damper due to the large / small diameter difference of the piston rod 13 The space volume of the fuel reservoir 11 is gradually increased with a definite volume.

As a result, the damper definite volume of the groove 15 compensates for the decrease in the space volume of the fuel reservoir 11 due to the descent of the piston 6, and this compensation for the decrease in space volume occurs as the piston 6 descends The occurrence of pulsation is reduced or prevented by attenuating or eliminating the negative compressive effect.

Meanwhile, FIGS. 4 and 5 are modified examples of the pulsating volume expansion unit according to the present invention.

Referring to FIG. 4 , the pulsating volume expansion part 10 is formed as a slot 16 using a piston rod 13 to replace the groove 15 of FIGS. 1 to 3 .

For example, the slot 16 is formed as a damper definite volume by being cut in a straight line to have a predetermined depth from the outer diameter of the piston rod 13. In particular, the slot 16 forms two symmetrically left / right or constant It may be formed in three or more at angular intervals.

Therefore, when the piston rod 13 is moved along with the piston 6 from the piston rising state (a) to the piston lowering state (b), the slot 16 is also moved in the same way as the groove 15 of FIGS. 1 to 3 By compensating for the decrease in the space volume of the fuel reservoir 11 according to the descent of the piston 6 with the damper definite volume of the slot 16, the instantaneous compression effect caused by the descent of the piston 6 is weakened or removed, thereby pulsating occurrence is reduced or prevented.

In addition, since the damper definitive volume of the slot 16 reduces the compensation for space volume reduction compared to the damper definitive volume of the groove 15 of FIGS. may have the advantage of being applied to

On the other hand, referring to FIG. 5 , the pulsation volume expansion part 10 is formed as a hole 17 using a piston rod 13 to replace the groove 15 of FIGS. 1 to 3 .

For example, the hole 17 is formed as a damper definite volume by being drilled with a predetermined diameter in the cylindrical body of the piston rod 13. In particular, the hole 17 is a first hole 17A and a second hole 17B A "+" cross-section structure is formed by crossing the holes. In this case, the first and second holes 17A and 17B may have the same diameter or different diameters.

Therefore, when the first and second holes 17A and 17B are also moved along with the piston 6, when the piston rod 13 is moved from the piston rising state (a) to the piston lowering state (b), the grooves of FIGS. 1 to 3 As in (15), the damper definitive volume of the slot 16 compensates for the decrease in the space volume of the fuel reservoir 11 according to the descent of the piston 6, thereby reducing the instantaneous compression effect caused by the descent of the piston 6 By attenuating or eliminating the occurrence of pulsation is reduced or prevented.

In addition, since the damper definite volume of the first and second holes 17A and 17B increases the compensation for the reduction in space volume compared to the damper definite volume of the groove 15 of FIGS. 1 to 3, It can have the advantage of being applied to high-pressure pumps with large specifications or capacities.

As described above, the pulsation volume expansion type high-pressure pump 1 according to the present embodiment is a piston rod 13 moving the space volume of the fuel reservoir 11, which is a pulsation generating place of the pump housing 2, together with the piston 6 ), it is possible to reduce the pulsation noise while increasing the control precision of the pump by removing the cause of pulsation by removing the cause of pulsation, and it is possible to secure the durability of components by preventing cavitation. In particular, by expanding the volume of the fuel reservoir according to the piston descent in the shape of the piston rod 13, performance is improved without increasing the size and weight of the pump, but there is no additional processing process, which is advantageous in price competitiveness.

1 : High pressure pump
2: pump housing 3: cylinder
4: flow control valve 5: discharge valve
6: piston 7: seal assembly
8 : Damper
10: pulsation volume expansion part
11: fuel reservoir 13: piston rod
15: groove 16: slot
17: holes 17A, 17B: first and second holes
20: damper euro
100: cam

Claims (15)

A pump housing having a compression chamber in which low-pressure fuel is converted into high-pressure fuel by a reciprocating piston, a fuel reservoir in which leaked fuel from the compression chamber is collected, and
A pulsating volume expansion unit that moves with the piston and communicates with the space of the fuel reservoir in a state in which the piston is lowered to increase the volume of the space
A high-pressure pump characterized in that it is included.
The method according to claim 1, wherein the pulsating volume expanding portion is formed on a piston rod integrally extending with the piston;
In the lowering position of the piston, the high-pressure pump, characterized in that the piston rod is located in a section of the piston rod facing the space of the fuel reservoir.
The high-pressure pump according to claim 2, wherein the piston rod section forms the pulsating volume expansion part with one of a groove, a slot, and a hole.
The high-pressure pump of claim 3, wherein each of the groove and the slot is formed by cutting an outer diameter of the piston rod.
The high-pressure pump according to claim 4, wherein the groove is formed in a circular circumferential structure.
[Claim 5] The high-pressure pump according to claim 4, wherein the slot is formed in a straight cross-sectional structure.
The high-pressure pump according to claim 6, wherein the straight cross-section structure forms left/right symmetry in the cross section of the piston rod.
The high-pressure pump according to claim 4, wherein the hole is formed by drilling an outer diameter of the piston rod.
The high-pressure pump according to claim 8, wherein the hole is composed of a first hole and a second hole.
The high-pressure pump according to claim 9, wherein the first hole and the second hole cross each other to form a “+” cross-sectional structure.
The method according to claim 1, wherein the piston is coupled with a cylinder that guides the movement to the cylinder guide area,
The high-pressure pump according to claim 1 , wherein the pulsation volume expansion part is covered by the cylinder guide area when the piston moves upward, while it leaves the cylinder guide area and communicates with the fuel reservoir when the piston moves downward.
The high-pressure pump of claim 1, wherein the fuel reservoir forms a closed space with a seal assembly provided at a lower portion of the pump housing.
The method according to claim 1, wherein the pump housing is provided with a flow control valve and a discharge valve,
The flow control valve adjusts the amount of compressed fuel entering the compression chamber,
The high-pressure pump, characterized in that the discharge valve discharges the compressed fuel from the compression chamber.
The method according to claim 1, wherein the pump housing is provided with a damper as a low-pressure fuel space,
The high-pressure pump, characterized in that the damper reduces the pressure fluctuation of the low-pressure fuel in the low-pressure fuel space.
15. The high-pressure pump of claim 14, wherein the low-pressure fuel space is communicated with the fuel reservoir through a damper passage opened in the pump housing.

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