JP2011214709A - On-off valve and fuel injection pump using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it hard for a flow separation to occur in a valve in which a flow direction undergoes a sudden change.SOLUTION: In a valve whose inlet port 511 extends in the radial direction of an outlet port 512, a central axis line J1 of the inlet port 511 is displaced from a central axis line J2 of the outlet port 512 and thereby when a fluid inflows from the inlet port 511 into the outlet port 512, the fluid becomes a swirling flow to proceed within the outlet port 512 while swirling. Accordingly, the flow separation becomes hard to occur within the outlet port 512.

Description

  The present invention relates to an on-off valve that opens and closes a fluid passage and a fuel injection pump using the on-off valve.

  A common rail fuel injection device for a diesel engine includes a fuel injection pump that supplies high pressure fuel to the common rail. This fuel injection pump pressurizes and discharges low-pressure fuel, and opens and closes a low-pressure fuel passage by an intake valve.

  In this intake valve, a low pressure fuel passage composed of an inlet hole and an outlet hole is formed in the valve body, and a valve needle held so as to be slidable back and forth in the valve body is in contact with and separated from a body side seat portion formed in the valve body. The low-pressure fuel passage is opened and closed. Moreover, the entrance hole and the exit hole are orthogonal (for example, refer patent document 1).

JP 2007-297994 A

  However, in the conventional intake valve, when the fuel flows from the inlet hole to the outlet hole, the flow direction changes suddenly (the flow direction changes by 90 degrees), and thus flow separation occurs in the outlet hole. When the separation zone exists in this way, there is a problem that the apparent passage area in the outlet hole is reduced and the flow coefficient is lowered. In particular, with the recent increase in the speed of fuel injection pumps, the flow rate of fuel passing through the low-pressure fuel passage is increased and flow separation tends to occur, and the problem of a decrease in the flow coefficient has become prominent.

  In view of the above points, an object of the present invention is to make it difficult for flow separation to occur.

  In order to achieve the above object, according to the first aspect of the present invention, a fluid passage including an inlet hole (511) and an outlet hole (512) is formed, and the body side sheet portion (514) is formed on the outlet hole (512) side. ) Formed on the valve body (51), and a valve needle (52) that is slidably supported by the valve body (51) and opens and closes the fluid passage by contacting and separating from the body side seat portion (514). The inlet hole (511) extends in the radial direction of the outlet hole (512), and the central axis of the inlet hole (511) is deviated from the central axis of the outlet hole (512).

  According to this, since the central axis of the inlet hole (511) is deviated from the central axis of the outlet hole (512), the fluid turns when the fluid flows into the outlet hole (512) from the inlet hole (511), The fluid travels through the exit hole (512) while swirling. Accordingly, separation of the flow in the outlet hole (512) is less likely to occur, the apparent passage area in the outlet hole (512) is prevented or suppressed, and the decrease in the flow coefficient is prevented or suppressed.

  The invention according to claim 2 is characterized in that in the on-off valve according to claim 1, a plurality of inlet holes (511) are provided. According to this, the passage area as the whole inlet hole (511) can be ensured easily.

  According to a third aspect of the present invention, in the on-off valve according to the second aspect, the central axis of all the inlet holes (511) is deviated from the central axis of the outlet hole (512).

  According to this, since the fluid that passes through any of the inlet holes (511) is a flow that surely turns when it flows into the outlet holes (512), a decrease in the flow coefficient is more reliably prevented or suppressed.

  According to a fourth aspect of the present invention, in the on-off valve according to the second or third aspect, the inlet holes (511) are arranged at equal intervals along the circumferential direction of the outlet hole (512). And

  According to this, the pressure of the fluid can easily act on the valve needle (52), and the surface pressure of the portion where the valve needle (52) slides can be made substantially uniform.

  As in the fifth aspect, the on-off valve (50) according to any one of the first to fourth aspects can be used as a valve for opening and closing a low-pressure fuel passage in the fuel injection pump.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is sectional drawing of the fuel injection pump which employ | adopted the valve which concerns on 1st Embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is sectional drawing of the inlet side non-return valve 50 in the fuel injection pump of FIG. It is sectional drawing which follows the XX line of FIG. It is sectional drawing of the valve which concerns on 2nd Embodiment of this invention. It is sectional drawing of the valve which concerns on 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of a fuel injection pump employing a valve according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  The fuel injection pump of the present embodiment is used in a common rail fuel injection device for an internal combustion engine (more specifically, a compression ignition internal combustion engine), and pressurizes and supplies fuel to a common rail that stores high-pressure fuel.

  As shown in FIGS. 1 and 2, the housing 11 of the pump is constituted by connecting a housing body 11a made of aluminum alloy and a bearing cover 11b made of aluminum alloy with bolts. A cam chamber 13 to which fuel is supplied from a feed pump, which will be described later, is formed in the housing 11, and both ends of the cam chamber 13 are closed by a pair of iron metal cylinder heads 12. The cam chamber 13 is connected to a fuel tank (not shown).

  The rotating shaft 14 is made of iron-based metal and is driven to rotate by an internal combustion engine (not shown). Specifically, a gear (not shown) is coupled to one end side (left side in FIG. 1) of the rotating shaft 14, and the gear on the internal combustion engine side is engaged with the gear, whereby the rotating shaft 14 is driven by the internal combustion engine. It has come to be.

  The rotating shaft 14 is rotatably held by two cylindrical bushes 15. One bush 15 is press-fitted and fixed to the housing body 11a, and the other bush 15 is press-fitted and fixed to the bearing cover 11b. An oil seal 16 seals between the rotary shaft 14 and the bearing cover 11b. A cam 17 having a circular cross section is formed eccentrically with respect to the rotating shaft 14 at an intermediate portion in the axial direction of the rotating shaft 14.

  A cam ring 18 that revolves around the rotating shaft 14 is fitted to the outer periphery of the cam 17. The cam ring 18 includes a cam ring main body 18a and a bush 18b integrated with the cam ring main body 18a. More specifically, the cam ring body 18a is made of an iron-based metal, has an outer shape of a quadrangular prism, and has a circular through hole. The bush 18b is formed in a cylindrical shape, is press-fitted into a through hole of the cam ring body 18a, and is slidable with the cam 17. The cam 17 and the cam ring 18 are accommodated in the cam chamber 13.

  On both sides of the cam ring 18, iron-based metal plungers 20 that reciprocate following the revolution of the cam ring 18 are arranged. The plunger 20 includes a columnar portion 20 a that is inserted into the cylinder head 12 so as to be reciprocally movable, and a bowl-shaped plunger head 20 b that is disposed in the cam chamber 13 and is opposed to the cam ring 18.

  The plunger 20 is urged toward the cam ring 18 by the spring 21 disposed in the cam chamber 13, and the plunger head 20 b is pressed against the cam ring 18. The contact surface between the cam ring 18 and the plunger head 20b is formed in a flat shape, and this prevents rotation of the cam ring 18, so that the cam ring 18 rotates while sliding with the plunger head 20b as the cam 17 rotates. Revolve without any problems.

  In the cylinder head 12, a pressurizing chamber 22 to which fuel is supplied from the feed pump 25 is formed on one end side (the counter plunger head 20 b side) of the cylindrical portion 20 a of the plunger 20. Further, in the cylinder head 12, only the fuel flow from the feed chamber 25 to the pressurizing chamber 22 and the fuel flow from the inlet chamber to the common rail (not shown) is allowed. A permissible outlet check valve 24 is provided.

  An inner gear type feed pump 25 is coupled to the other end side of the rotating shaft 14 (on the right side in FIG. 1). The feed pump 25 is housed in the pump cover 26 so as to be rotatable. The feed pump 25 is driven to rotate by the rotating shaft 14 to pressurize and discharge the fuel sucked from the fuel tank.

  The fuel discharged from the feed pump 25 is supplied to the pressurizing chamber 22 through a fuel passage and an inlet side check valve 50 (not shown). A metering valve (not shown) for metering the amount of fuel supplied to the pressurizing chamber 22 according to the operating state of the internal combustion engine is provided in the middle of the fuel passage.

  Next, the inlet side check valve 50 as an on-off valve will be described with reference to FIGS. 3 is a cross-sectional view of the inlet check valve 50 in the fuel injection pump of FIG. 1, and FIG. 4 is a cross-sectional view taken along the line XX of FIG.

  As shown in FIGS. 3 and 4, the inlet side check valve 50 includes a valve body 51, a valve needle 52, a stopper 53, and a spring 54.

  In the valve body 51, an inlet hole 511, an outlet hole 512, a guide hole 513, and a body side seat portion 514 are formed. The inlet hole 511 and the outlet hole 512 constitute the fluid passage of the present invention, and the fuel discharged from the feed pump 25 (see FIG. 1) flows into the inlet hole 511 and then passes through the outlet hole 512. It is supplied to the pressurizing chamber 22 (see FIG. 1).

  In addition, a plurality of inlet holes 511 (four in this example) are provided, and one outlet hole 512 is provided. The inlet holes 511 are arranged at equal intervals along the circumferential direction of the outlet holes 512. Each of the inlet hole 511 and the outlet hole 512 is a hole having a circular cross section, the inlet hole 511 extends substantially in the radial direction of the outlet hole 512, and the inlet hole 511 and the outlet hole 512 are orthogonal to each other.

  The central axis J1 of all the inlet holes 511 is deviated (ie, offset) from the central axis J2 of the outlet holes 512. Here, assuming that the amount of deviation between the central axis J1 of the inlet hole 511 and the central axis J2 of the outlet hole 512 is an offset amount L, the inner diameter of the inlet hole 511 is d1, and the inner diameter of the outlet hole 512 is d2, L = φd2 / 4 and φd1 = φd2 / 2.

  In this way, among the inner wall surfaces of the inlet hole 511, the first inner wall surface 511a located on the side opposite to the outlet hole center axis J2 from the inlet hole center axis J1 and farthest from the inlet hole center axis J1 is Tangent to the inner wall surface of the outlet hole 512. Further, among the inner wall surfaces of the inlet hole 511, the extension line of the second inner wall surface 511b located on the outlet hole center axis J2 side of the inlet hole center axis J1 and farthest from the inlet hole center axis J1 is the outlet line. It coincides with the central axis J2 of the hole 512.

  The guide hole 513 is a hole having a circular cross section, and is formed coaxially with the outlet hole 512. A stepped columnar valve needle 52 is slidably held in the guide hole 513. The body side seat portion 514 is formed in a tapered shape and is located on the downstream side of the fuel flow with respect to the outlet hole 512.

  One end of the valve needle 52 is formed with a valve needle side seat portion 521 that opens and closes the passage by contacting and separating from the body side seat portion 514. In addition, a guide shaft portion 522 that is inserted into the guide hole 513 is formed at the axial direction intermediate portion of the valve needle 52.

  Further, the valve needle 52 is formed with a reduced diameter portion 523 having a diameter smaller than the inner diameter of the outlet hole 512 between the valve needle side seat portion 521 and the guide shaft portion 522, and the reduced diameter portion 523 and the outlet hole 512. A cylindrical space is formed between the two.

  A stopper 53 for restricting the lift amount of the valve needle 52 is press-fitted and fixed to the other end of the valve needle 52. A spring 54 is disposed between the stopper 53 and the valve body 51 to urge the valve needle 52 in the valve closing direction.

  Next, the operation of the fuel injection pump configured as described above will be described. When the rotary shaft 14 is driven and rotated by the internal combustion engine, the feed pump 25 is driven by the rotating operation of the rotary shaft 14, and the feed pump 25 sucks fuel from the fuel tank, pressurizes it, and discharges it.

  Further, the cam 17 rotates with the rotation of the rotating shaft 14, the cam ring 18 revolves without rotating with the rotation of the cam 17, and the plunger 20 reciprocates with the revolution of the cam ring 18.

  When the plunger 20 at the top dead center moves toward the bottom dead center with the revolution of the cam ring 18, the fuel pressure in the pressurizing chamber 22 decreases, and the pressure of the fuel discharged from the feed pump 25 and the pressurizing chamber 22 are reduced. The pressure difference from the internal fuel pressure increases and the inlet side check valve 50 opens. As a result, the fuel discharged from the feed pump 25 flows into the pressurizing chamber 22 through the inlet side check valve 50.

  When the plunger 20 that has reached the bottom dead center moves again toward the top dead center, the inlet side check valve 50 is closed, and the fuel pressure in the pressurizing chamber 22 increases. When the fuel pressure in the pressurizing chamber 22 rises, the outlet side check valve 24 opens and high-pressure fuel is supplied to the common rail.

  Next, the fuel flow when the inlet check valve 50 is opened and fuel is supplied to the pressurizing chamber 22 will be described. In this embodiment, since the inlet hole center axis J1 is deviated from the outlet hole center axis J2, the fuel that has passed through the inlet hole 511 swirls around the reduced diameter portion 523 when flowing into the outlet hole 512. Become. More specifically, a part of the fuel that has passed through the inlet hole 511 collides with the reduced diameter portion 523. However, since L = φd2 / 4 and φd1 = φd1 / 2, all the fuel is in the reduced diameter portion 523. It flows in the same direction along the outer wall surface or the inner wall surface of the outlet hole 512.

  The fuel that has flowed into the outlet hole 512 advances in the outlet hole 512 in the direction of the outlet hole central axis J2 while turning, and flows into the pressurizing chamber 22. As described above, the fuel becomes a swirling flow and advances in the outlet hole 512, so that the separation of the flow in the outlet hole 512 is less likely to occur, and the reduction of the apparent passage area in the outlet hole 512 is prevented or suppressed. Thus, the reduction of the flow coefficient is prevented or suppressed.

  In addition, since all the inlet hole center axis J1 is deviated from the outlet hole center axis J2, the fuel passing through any of the inlet holes 511 is surely swirled when flowing into the outlet hole 512. A decrease in the flow coefficient is reliably prevented or suppressed.

  Furthermore, since a plurality of inlet holes 511 are provided, the passage area of the whole inlet hole 511 can be easily secured. Furthermore, since the inlet holes 511 are arranged at equal intervals along the circumferential direction of the outlet hole 512, the pressure of the fuel is easily applied to the valve needle 52, and the portion where the valve needle 52 slides is facilitated. The surface pressure can be made substantially uniform.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 5 is a sectional view of a valve according to the second embodiment. Only the parts different from the first embodiment will be described below.

  As shown in FIG. 5, in this embodiment, the offset amount L is reduced. That is, 0 <L <φd2 / 4. However, φd1 = φd2 / 2. In this way, the outlet hole central axis J2 is located between the extension line of the first inner wall surface 511a and the extension line of the second inner wall surface 511b. In other words, when the inlet hole 511 is viewed along the inlet hole central axis J1, the outlet hole central axis J2 is located in the projection plane of the inlet hole 511.

  Here, a line parallel to the inlet hole central axis J1 and passing through the outlet hole central axis J2 is defined as a reference line S. In this case, the fuel flowing between the reference line S and the second inner wall surface 511b in the inlet hole 511 collides with the reduced diameter portion 523, and then tries to turn counterclockwise on the paper surface of FIG. Of these, the fuel flowing between the reference line S and the first inner wall surface 511a collides with the reduced diameter portion 523 and then tries to turn clockwise on the paper surface of FIG.

  Since the fuel flowing between the reference line S and the first inner wall surface 511a in the inlet hole 511 has a higher flow rate and a stronger clockwise flow, the fuel swirls clockwise as a whole. Therefore, as in the first embodiment, separation of the flow in the outlet hole 512 is less likely to occur, the apparent passage area in the outlet hole 512 is prevented or suppressed, and the flow coefficient is prevented from decreasing. It is suppressed.

(Third embodiment)
A third embodiment of the present invention will be described. FIG. 6 is a sectional view of a valve according to the third embodiment. Only the parts different from the first embodiment will be described below.

  As shown in FIG. 6, in this embodiment, in order to prevent the fuel that has passed through the inlet hole 511 from hitting the reduced diameter portion 523 when flowing into the outlet hole 512, the offset amount L is increased, and The inner diameter d1 of the inlet hole 511 is reduced. Further, as the inner diameter d1 of the inlet hole 511 is reduced, the number of the inlet holes 511 is increased (six in this example) to secure a necessary passage area.

  According to this, since the fuel does not hit the reduced diameter portion 523 when the fuel flows into the outlet hole 512, the flow of the fuel in the outlet hole 512 becomes smooth, and the reduction of the flow coefficient is more reliably prevented or suppressed. .

(Other embodiments)
In each of the above embodiments, the central axis J1 of all the inlet holes 511 is offset with respect to the central axis J2 of the outlet holes 512, but only some of the inlet holes 511 may be offset.

  Further, in each of the above embodiments, an example in which the on-off valve of the present invention is applied to a fuel injection pump used in a common rail fuel injection device for a compression ignition type internal combustion engine has been shown, but the on-off valve of the present invention is used for applications other than pumps. It can also be applied to.

  Furthermore, the above embodiments can be arbitrarily combined within a feasible range.

51 Valve Body 52 Valve Needle 511 Inlet Hole 512 Outlet Hole 514 Body Side Seat

Claims (5)

A valve body (51) in which a fluid passage including an inlet hole (511) and an outlet hole (512) is formed, and a body side seat portion (514) is formed on the outlet hole (512) side;
A valve needle (52) that is held by the valve body (51) so as to be slidable back and forth, and that opens and closes the fluid passage by contacting and separating from the body side seat portion (514);
The inlet hole (511) extends in the radial direction of the outlet hole (512), and the central axis of the inlet hole (511) is deviated from the central axis of the outlet hole (512). .   The on-off valve according to claim 1, wherein a plurality of the inlet holes (511) are provided.   The on-off valve according to claim 2, wherein the central axis of all the inlet holes (511) is offset from the central axis of the outlet holes (512).   The on-off valve according to claim 2 or 3, wherein the inlet holes (511) are arranged at equal intervals along the circumferential direction of the outlet holes (512).   5. A fuel injection pump that pressurizes and discharges low-pressure fuel, and includes the on-off valve (50) according to any one of claims 1 to 4, wherein the on-off valve (50) allows the low-pressure fuel to be discharged. A fuel injection pump characterized in that a passage is opened and closed.

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