JP2008304017A - Three-way selector valve and fuel injection device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-way selector valve for suppressing energy loss due to the flow of fluid out of a back pressure chamber in which the fluid flows to energize a valve element, into a low pressure passage; and to provide a fuel injection device using the selector valve. <P>SOLUTION: The three-way selector valve 51 comprises a valve chest 61 storing the first and second valve elements 7, 8. The first and second valve elements 7, 8 are slidably supported, and first and second back pressure chambers 62, 63 are formed on the other end sides of the valve elements. The first valve element 7 is operated with a pressure difference between the first back pressure chamber 62 and the valve chest 61 to open/close a control fuel supply passage 96. The second valve element 8 is operated with a pressure difference between the valve chest 61 and the second back pressure chamber 63 to open/close a second return passage 99. The second valve element 8 has an inner periphery side abutting portion 821 between a second sliding portion 83 of the second valve element 8 and the second return passage 99 for abutting on a lower end face 617 of the valve chest 61 when the second valve element 8 closes the second return passage 99. Thus, high pressure fuel is prevented from flowing out of the second back pressure chamber 63 via the second sliding portion 83 into the second return passage 99. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a three-way switching valve and a fuel injection device using the same.

  2. Description of the Related Art Conventionally, there is known a pressure-intensifying fuel injection device that receives high-pressure fuel from a fuel supply source such as a common rail, and further injects the received high-pressure fuel into a cylinder (see Patent Document 1).

  This pressure-increasing fuel injection device includes a nozzle that injects fuel, a pressure-increasing device that supplies fuel to the nozzle by increasing pressure, an electromagnetic valve that opens and closes in response to a command from a predetermined electronic control unit (ECU), A three-way switching valve that switches between a flow path for operating the pressure booster and a flow path for stopping the operation of the pressure booster according to opening and closing of the valve.

  The three-way switching valve switches between a state in which the high-pressure fuel in the common rail flows into the pressure-increasing control chamber and a state in which the high-pressure fuel in the pressure-increasing control chamber flows out, and operates the pressure increasing device to increase the fuel pressure. The operation of the pressure increasing device is stopped to stop the pressure increase of the fuel.

  The three-way switching valve includes two valve bodies that move independently and a body in which a valve chamber that houses the valve body portions of the two valve bodies is formed. In the body, three fuel passages leading to the valve chamber are formed. The first fuel passage is a high pressure passage through which common rail high pressure fuel flows, and the second fuel passage is a low pressure passage that discharges fuel in the valve chamber to a low pressure source (for example, a fuel tank). The third fuel passage is a control passage that communicates the valve chamber and the pressure increase control chamber of the pressure increase device. Note that the pressure increase control chamber performs pressure increase and stop of pressure increase through the flow of fuel in and out.

  The two valve bodies are supported by the body so as to be slidable in the axial direction. One valve body opens and closes the high-pressure passage, and the other valve body opens and closes the low-pressure passage. One valve body opens the high-pressure passage, and the other valve body closes the low-pressure passage, so that a high-pressure fuel in the common rail is supplied to the pressure-increasing control chamber. One valve body closes the high-pressure passage, and the other valve body opens the low-pressure passage, so that the high-pressure fuel in the pressure increase control chamber is discharged to the low-pressure source.

In the body, a back pressure chamber into which high-pressure fuel for urging each valve body toward the valve chamber flows is formed at the end of each valve body opposite to the valve chamber. By adjusting the pressure in the back pressure chamber, the pressure difference acting on each valve body is controlled, and each valve body is moved independently. In this prior art, when switching from the first state to the second state, after each valve body closes the high pressure passage, the other valve body opens the low pressure passage. To control the pressure difference acting on. As a result, when switching from the first state to the second state, the energy loss of the high-pressure source (for example, the energy spent to increase the pressure of the fuel) due to the state where the high-pressure passage and the low-pressure passage communicate with each other Loss (hereinafter simply referred to as energy loss).
JP 2006-104971 A

  However, the other valve body of the above-described conventional three-way switching valve has a contact portion that contacts the inner wall surface of the valve chamber, and the opening portion of the low-pressure passage that opens to the valve chamber by contacting the inner wall surface. Occlude. Thereby, the fuel in the valve chamber is prevented from flowing out into the low pressure passage. The other valve body is slidable in a through hole formed in a wall that partitions the back pressure chamber and the low pressure passage of the valve body, which is formed on the end side opposite to the valve chamber of the other valve body. It is supported by. Since the through hole is formed outside the valve chamber, the high pressure fuel in the back pressure chamber always flows into the low pressure passage through the sliding gap between the through hole and the side wall of the valve body, resulting in energy loss. There is a problem that occurs. This fuel outflow always occurs in the first state and the second state.

  The present invention relates to a three-way switching valve capable of suppressing the generation of energy loss due to the flow of high-pressure fluid in a back pressure chamber into which a high-pressure fluid for energizing a valve body flows into a low-pressure passage, and fuel injection using the same An object is to provide an apparatus.

According to the first aspect of the present invention, there are three methods for switching between the first state in which the high pressure fluid from the high pressure source is supplied to the control chamber of the fluid device and the second state in which the high pressure fluid in the control chamber is discharged to the low pressure source. In the switching valve,
A body having a high pressure passage communicating with a high pressure source, a control passage communicating with a control chamber, and a valve chamber in which a low pressure passage communicating with a low pressure source is opened; and a first valve body for opening and closing an opening of the high pressure passage, One end portion is accommodated in the valve chamber, and the other end portion is accommodated in a first back pressure chamber formed in a body into which a high-pressure fluid of a high-pressure source biased toward the one end portion flows. When the pressure of the fluid in the first back pressure chamber decreases from a predetermined value, the first side wall is moved to the first back pressure chamber side and closes the opening of the high pressure passage. A second valve body that opens and closes a valve body and an opening of a low-pressure passage, the body having one end housed in a valve chamber and the other end urged toward the one end side into a body into which high-pressure fluid from a high-pressure source flows The side wall between one end and the other end is slidably supported by the body, and is accommodated in the formed second back pressure chamber. When the force is reduced from the predetermined value, to move the valve chamber side includes a second valve body to open the opening of the low-pressure passage, a,
In the transition period in which the first state is switched to the second state, the pressure of the fluid in the first back pressure chamber and the valve chamber is adjusted so that the second valve body has the opening of the high pressure passage. A three-way switching valve that opens the opening of the low-pressure passage after being closed,
When the second valve body closes the opening of the low-pressure passage, the second valve body has a shaft of the second valve body between the sliding portion of the second valve body and the body and the opening of the low-pressure passage. It is characterized by having a first abutting portion that abuts against the inner wall of the valve chamber as the direction moves and prevents the flow of fluid from the sliding portion to the opening of the low-pressure passage.

  According to this configuration, one end of each of the first valve body that opens and closes the high-pressure passage and the second valve body that opens and closes the low-pressure passage is accommodated in the valve chamber, and the other end of each valve body is connected to the high-pressure source. Are accommodated in the first and second back pressure chambers into which the high pressure fluid flows. Accordingly, the first valve body moves due to the pressure difference between the first back pressure chamber and the valve chamber, and the second valve body moves due to the pressure difference between the second back pressure chamber and the valve chamber.

  Furthermore, the first valve body closes the opening of the high-pressure passage when the fluid pressure in the first back pressure chamber decreases from a predetermined value. The second valve body opens the opening of the low-pressure passage when the fluid pressure in the valve chamber decreases from a predetermined value. By adjusting the fluid pressure in the first back pressure chamber and the valve chamber during the transition period from the first state to the second state, the second valve body closes the opening of the high pressure passage. After that, the opening of the low pressure passage is opened. As a result, it is possible to avoid a state in which the opening of the high pressure passage and the opening of the low pressure passage communicate with each other through the valve chamber in the transition period.

  Furthermore, when the second valve body closes the opening of the low pressure passage, the second valve body is placed on the inner wall of the valve chamber between the sliding portion of the second valve body and the body and the opening of the low pressure passage. Since the first abutting portion that abuts and prevents the flow of fluid from the sliding portion to the opening of the low-pressure passage is provided, the high-pressure fluid in the second back pressure chamber passes through the sliding portion through the low-pressure passage. The generation of energy loss due to outflow can be suppressed.

  According to invention of Claim 2, the 1st valve body and the 2nd valve body are arrange | positioned at the body so that each center axis line of a 1st valve body and a 2nd valve body may correspond substantially, When in the state 2, the first valve body presses the second valve body in a direction in which the first contact portion is pressed against the inner wall of the valve chamber.

  According to this configuration, not only the urging force due to the fluid pressure of the valve chamber but also the urging force from the first valve body is urged on the second valve body, so that the first abutting portion is applied to the inner wall of the valve chamber. The degree of adhesion when abutting can be further increased.

  According to the invention described in claim 3, the second valve body includes a valve body portion accommodated in the valve chamber, and a sliding portion having a diameter smaller than that of the valve body portion and supported slidably on the body. The first abutting portion protrudes toward the inner wall of the valve chamber in which the opening of the low pressure passage is formed on the end surface of the valve body portion on the sliding portion side, and the end surface is the second valve When viewed from the axial direction of the body, it is formed so as to surround the sliding portion, and further, the end surface of the valve body portion is on the outer peripheral side of the first contact portion, and the opening portion of the low pressure passage and the control passage A second abutting portion that abuts against the inner wall of the valve chamber between the first and second openings is formed so as to protrude toward the inner wall of the valve chamber.

  According to this configuration, if the fluid pressures in the valve chamber and the second back pressure chamber are substantially the same, when the second contact portion is in contact with the inner wall of the valve chamber, the inner circumference is more than the second contact portion. The fluid pressure of the valve chamber does not act on the side. As a result, the urging force that acts on the second valve element is stronger than the urging force that moves the second valve element toward the second back pressure chamber. For this reason, obstruction | occlusion of the opening part of a low pressure channel | path can be maintained by the 2nd valve body.

  And since the 1st contact part and the 2nd contact part are formed so that it may protrude toward the inner wall of a valve chamber from the end face of the valve body part of the 2nd valve body, the 2nd valve body is the 2nd. By only moving to the back pressure chamber side, the high pressure fluid in the second back pressure chamber can be prevented from flowing out to the low pressure passage through the sliding portion, and at the same time, the fluid in the valve chamber can also be prevented from flowing out to the low pressure passage. .

  According to the fourth aspect of the present invention, the first valve body is formed with a communication path that communicates the first back pressure chamber and the valve chamber. According to this configuration, the fluid in the valve chamber can be discharged simultaneously by only discharging the fluid in the first back pressure chamber. In other words, it is possible to adjust the pressure in another space only by adjusting the pressure in one space, and it is not necessary to provide a device for controlling the pressure separately.

  According to the fourth aspect of the present invention, since the communication path is formed in the first valve body, the fluid in the first back pressure chamber is discharged and the fluid in the valve chamber also passes through the first back pressure chamber. It is discharged via. Further, when the second valve body opens the opening of the low pressure passage, the fluid in the valve chamber is also discharged from the low pressure passage. Therefore, the fluid in the valve chamber is discharged from the two passages, and the speed at which the fluid pressure in the valve chamber decreases is faster than when the fluid is discharged from one passage (only the low-pressure passage).

  According to the invention described in claim 5, in the transition period in which the communication path is switched from the first state to the second state, the pressure of the fluid in the valve chamber is reduced from the predetermined value, and the second valve body is in a low pressure state. After opening the opening of the passage, the passage is closed by the second valve body, and an increase in the fluid pressure drop speed of the control chamber can be suppressed.

According to invention of Claim 6, it is a fuel-injection apparatus provided with the three-way switching valve as described in any one of Claims 1-5, Comprising: It has an injection hole in the front-end | tip, The injection hole A nozzle that injects fuel from the nozzle, a pressure-increasing chamber into which fuel supplied to the nozzle flows, a pressure-increasing piston that supplies pressure to the nozzle, and a fluid that controls the operation of the pressure-increasing piston. A pressure increasing device having a control chamber for flowing in and out,
The control passage of the three-way switching valve communicates with the control chamber of the pressure booster, and the three-way switching valve switches between the first state and the second state, so that the high-pressure fuel as the high-pressure fluid of the high-pressure source Is supplied to the control room, the high pressure fuel in the control room is discharged to the low pressure source, and the pressure intensifier is driven or stopped.

  According to the three-way switching valve according to any one of claims 1 to 5, when the first state is switched to the second state, and the generation of energy loss is in the first state. Since it can be suppressed, the use of this as a valve for driving the pressure booster of the fuel injection device can suppress the occurrence of energy loss in the fuel injection device. As a result, an increase in fuel consumption of the internal combustion engine in which the fuel injection device is mounted can be suppressed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a fuel injection device using the three-way switching valve of the present invention. The fuel injection device 1 supplies fuel into a combustion chamber of each cylinder of a diesel engine (not shown: hereinafter referred to as an engine), for example. The fuel injection device 1 is connected to a common rail 2 that accumulates high-pressure fuel via a high-pressure fuel supply passage 9. A supply pump 21 is connected to the common rail 2. The supply pump 21 includes a variable discharge amount mechanism and pressurizes the fuel in the fuel tank 22 as a low pressure source and pumps the fuel to the common rail 2.

  The fuel injection device 1 controls the pressure increasing device 4 for increasing the pressure of the fuel in the common rail 2, the nozzle 3 for injecting the fuel increased in pressure by the pressure increasing device 4, and the pressure increasing device 4 and the nozzle 3. The control unit 5 is provided. The pressure booster 4 and the nozzle 3 operate using the pressure of the high-pressure fuel supplied from the common rail 2. The control unit 5 controls the operation of the pressure booster 4 and the nozzle 3 by controlling the flow of the high-pressure fuel supplied to the pressure booster 4 and the nozzle 3. The control unit 5 includes a three-way switching valve 51 that operates with the pressure of high-pressure fuel, and an electromagnetic valve 52 that controls the switching operation of the three-way switching valve 51. Details of the three-way switching valve 51 will be described later. The fluid device described in the claims corresponds to the pressure booster 4.

  The nozzle 3 has a needle 32 that opens and closes the injection hole 31, and includes an injection control chamber 33 and an injection hole 31 through which fuel flows in and out of the needle 32 in a direction in which the injection hole 31 is closed (valve closing direction). A fuel reservoir chamber 34 into which fuel that exerts pressure in the opening direction (valve opening direction) flows in and out is formed. In addition, the nozzle 3 houses a spring 35 that urges the needle 32 in the valve closing direction in the injection control chamber 33. That is, the needle 32 is urged in the valve closing direction by the fuel pressure in the injection control chamber 33 and the spring 35, and is urged in the valve opening direction by the fuel pressure in the fuel reservoir chamber 34.

  The fuel reservoir chamber 34 communicates with the pressure increasing chamber 44 of the pressure increasing device 4 through the fuel supply passage 93. The pressure increasing chamber 44 is a space in which fuel is increased in the pressure increasing device 4, and the pressure increasing device 4 increases the pressure higher than the fuel pressure in the fuel injection control chamber 33 and supplies it to the fuel reservoir chamber 34. .

  The injection control chamber 33 is connected to an injection control passage 91 that branches from a high-pressure fuel supply passage 9 that connects the common rail 2 and the high-pressure chamber 43, and a fuel passage 92 that branches from the injection control passage 91 is connected to the injection control passage 91. Connect separately.

  The injection control passage 91 is provided with an orifice 911 that regulates the flow rate of fuel flowing into and from the injection control chamber 33, and the fuel passage 92 is a check valve 921 that allows only fuel to flow into the injection control chamber 33. Is provided in parallel with the orifice 911. The fuel flows from the common rail 2 to the injection control chamber 33 through the high-pressure fuel supply passage 9, the injection control passage 91, the fuel passage 92 and the orifice 911, and the fuel flows out from the injection control chamber 33 through the injection control passage 91 and the orifice 911. To do.

  With the above configuration, the nozzle 3 injects fuel into the combustion chamber of the cylinder according to the operation of the pressure increasing device 4. That is, when the fuel pressure is increased by the pressure increasing device 4, the increased pressure fuel flows into the fuel reservoir chamber 34 through the fuel supply passage 93. As a result, the urging force due to the pressure in the fuel reservoir chamber 34 becomes stronger than the resultant force of the urging force due to the pressure in the injection control chamber 33 and the urging force due to the spring 35, so that the needle 32 is displaced in the valve opening direction and the injection hole 31. Is released. For this reason, the fuel is injected from the injection hole 31, and at the same time, the fuel flows out from the injection control chamber 33 through the injection control passage 91 and the orifice 911.

  Further, when the pressure increase of the fuel by the pressure increasing device 4 is stopped, the increased pressure fuel does not flow into the fuel reservoir chamber 34. As a result, the urging force due to the pressure in the fuel reservoir chamber 34 becomes weaker than the resultant force of the urging force due to the pressure in the injection control chamber 33 and the urging force due to the spring 35, so that the needle 32 is displaced in the valve closing direction, The check valve 921 opens and fuel flows into the injection control chamber 33 through the high-pressure fuel supply passage 9, the injection control passage 91 and the fuel passage 92. For this reason, the injection hole 31 is closed and fuel injection stops.

  The pressure booster 4 boosts the fuel based on Pascal's principle, and has a pressure boosting piston 41 whose diameter changes in two stages, large and small, toward one end in the axial direction. The pressure booster 4 receives the pressure of the fuel at the large-diameter high-pressure surface 412 and applies a biasing force based on this pressure to the fuel via the small-diameter pressure-increasing surface 414 to increase the fuel pressure.

  The pressure increasing piston 41 includes a small diameter piston portion 413 on one end side and a large diameter piston portion 411 on the other end side. One end surface of the small diameter piston portion 413 forms a pressure increasing surface 414 and the other end surface of the large diameter piston portion 411. Forms the high pressure surface 412. The pressure-increasing piston 41 is accommodated in a cylinder 42 whose diameter changes in two steps of large and small toward one end in the axial direction, and reciprocates in the cylinder 42 in the axial direction. The cylinder 42 has a small diameter cylinder part 422 in which the side wall of the small diameter piston part 413 slides, and a large diameter cylinder part 421 in which the side wall of the large diameter piston part 411 slides.

  Further, when the pressure-increasing piston 41 is accommodated in the cylinder 42 such that the small diameter piston portion 413 slides on the small diameter cylinder portion 422 and the large diameter piston portion 411 slides on the large diameter cylinder portion 421, the large diameter piston portion. A high pressure chamber 43 is formed on the high pressure surface 412 side of 411, and a pressure increasing chamber 44 is formed on the pressure increasing surface 414 side of the small diameter piston portion 413. The pressure-increasing piston 41 is formed with a communication passage 415 that opens to the high-pressure surface 412 and opens to the pressure-increasing surface 414 on the other side. A check valve 416 that allows only a flow from the high pressure surface 412 toward the pressure increasing surface 414 is provided in the middle of the communication path 415.

  The high pressure chamber 43 communicates with the common rail 2 through the high pressure fuel supply passage 9, and the high pressure fuel accumulated in the common rail 2 flows into the high pressure chamber 43. Further, the high pressure chamber 43 communicates with the three-way switching valve 51 through the second control pressure supply passage 97.

  The pressure increasing chamber 44 communicates with the high pressure chamber 43 through the communication passage 415, and the high pressure fuel in the high pressure chamber 43 flows in. Further, the pressure increasing chamber 44 communicates with the nozzle 3 through the fuel supply passage 93, and the fuel increased in pressure in the pressure increasing chamber 44 is supplied to the nozzle 3.

  Between the high pressure chamber 43 and the pressure increasing chamber 44, one end side end surface of the large diameter piston portion 411, one end side end surface of the large diameter cylinder portion 421, the side wall surface of the large diameter cylinder portion 421, and the small diameter piston portion 413 side. A pressure increase control chamber 45 is formed as a control chamber according to the claims defined by the wall surface. The pressure increase control chamber 45 accommodates a spring 451 that biases the large diameter piston portion 411 toward the other end. The pressure increase control chamber 45 communicates with the three-way switching valve 51 through a pressure increase control passage 94 as a control passage according to the claims.

  With the above configuration, the pressure booster 4 performs pressure increase and stop of pressure increase through the flow of fuel into and out of the pressure increase control chamber 45. That is, when the fuel flows out from the pressure increase control chamber 45, the fuel flows into the high pressure chamber 43 and the pressure increasing piston 41 is displaced to one side, and the fuel in the pressure increasing chamber 44 is increased and supplied to the fuel reservoir chamber 34. The When the fuel flows into the pressure increase control chamber 45, the pressure increase piston 41 is displaced to the other, the check valve 416 opens, the fuel in the high pressure chamber 43 flows into the pressure increase chamber 44, and the fuel in the pressure increase chamber 44 The pressure increase is stopped, and fuel is not supplied to the fuel reservoir 34.

  The solenoid valve 52 is provided in a first return passage 98 that connects the fuel tank 22, which is a low pressure source, and the first back pressure chamber 62 of the three-way switching valve 51, and fuel flows in and out from the first back pressure chamber 62. Is to operate. The electromagnetic valve 52 is a two-way valve that opens and closes in response to a command from an ECU (not shown).

  The three-way switching valve 51 has a first state in which the high-pressure fuel accumulated in the common rail 2 is supplied to the pressure-increasing control chamber 45 of the pressure-increasing device 4, and the high-pressure fuel supplied to the pressure-increasing control chamber 45 in the fuel tank 22. It is a valve which switches between the 2nd state discharged to. The state illustrated in FIG. 2 shows the first state.

  FIG. 2 is a cross-sectional view of the three-way switching valve 51. As shown in FIG. 2, the three-way switching valve 51 is configured by accommodating a part of the first valve body 7 and the second valve body 8 in a valve chamber 61 formed in the body 6. The 1st valve body 7 and the 2nd valve body 8 are arrange | positioned along with each center axis line so that it may correspond substantially. The inner diameter of the valve chamber 61 increases toward the lower side in FIG.

  A high pressure port 611 serving as an opening portion of the high pressure passage described in the claims is opened on a side surface of the valve chamber 61 on the small diameter portion side, and the control fuel branched from the high pressure fuel supply passage 9 is provided in the high pressure port 611. A supply passage 96 is connected. A low pressure port 612 as an opening of the low pressure passage described in the claims is opened on the lower end surface 617 (large diameter portion side) of the valve chamber 61, and the low pressure port 612 is connected to the fuel tank 22. The 2nd return channel | path 99 as a low voltage | pressure channel | path as described in a term is connected. Further, a control port 613 is opened on the side surface of the valve chamber 61 on the large diameter portion side, and a pressure increase control passage 94 communicating with the pressure increase control chamber 45 is connected.

  A first cylinder portion 614 extending upward in FIG. 2 is formed on the upper end surface of the valve chamber 61 on the small diameter portion side. An orifice 621 is formed on the upper end surface of the first cylinder portion 614. The orifice 621 is opened and closed by the electromagnetic valve 52.

  A second cylinder portion 615 extending downward in FIG. 2 is formed on the lower end surface 617 of the valve chamber 61. A second control pressure supply passage 97 communicating with the high pressure chamber 43 is connected to the lower end surface of the second cylinder portion 615. As shown in FIG. 4, a plurality of low pressure ports 612 are annularly arranged around the second cylinder portion 615.

  The first valve body 7 has a first valve body portion 71 accommodated in the valve chamber 61 and a first valve body 71 having an outer diameter smaller than that of the first valve body portion 71 and slidable in the axial direction with respect to the first cylinder portion 614. A sliding portion 72 is provided. Since the outer diameter of the first valve body portion 71 is larger than the inner diameter of the valve chamber 61 on the smaller diameter portion side, when the first valve body 7 moves upward, the upper end surface of the first valve body portion 71 is the smaller diameter of the valve chamber 61. The first valve seat portion 616 formed between the portion and the large diameter portion.

  Since the high pressure port 611 is opened above the first valve seat portion 616, when the first valve body portion 71 comes into contact with the first valve seat portion 616, the high pressure port 611 is closed and the common rail 2 The high-pressure fuel is prevented from flowing into the valve chamber 61. When the first valve body 7 moves downward, the first valve body portion 71 is separated from the first valve seat portion 616, so that high-pressure fuel flows from the high-pressure port 611 into the valve chamber 61.

  When the first sliding portion 72 is slidably accommodated in the first cylinder portion 614, the first back pressure chamber 62 formed by the upper end surface of the first sliding portion 72 and the inner wall of the first cylinder portion 614. Is formed. A first control pressure supply passage 95 branched from the high pressure fuel supply passage 9 is connected to the side surface of the first back pressure chamber 62. An orifice 951 is formed in the first control pressure supply passage 95 to limit the amount of high-pressure fuel in the common rail 2 that flows into the first back pressure chamber 62.

  As described above, the orifice 621 is controlled to open and close by the electromagnetic valve 52. When the solenoid valve 52 opens the orifice 621, the high-pressure fuel in the first back pressure chamber 62 is discharged to the first return passage 98 through the orifice 621, and the pressure in the first back pressure chamber 62 decreases (see FIG. 1). The diameter of the orifice 621 is set such that the pressure of the first back pressure chamber 62 decreases when the solenoid valve 52 opens the orifice 621. The first back pressure chamber 62 accommodates a spring 623 that biases the first valve body 7 downward.

  Further, a communication path 73 is formed in the first valve body 7 along the central axis of the first valve body 7. The communication path 73 is a path that connects the valve chamber 61 and the first back pressure chamber 62, and has an orifice 74 in the middle.

  The first valve body 7 is urged in the direction to open the high pressure port 611 by the fuel pressure in the first back pressure chamber 62 and the spring 623, and the direction in which the high pressure port 611 is closed by the fuel pressure in the valve chamber 61. Is being energized.

  As shown in FIG. 2, when the solenoid valve 52 closes the orifice 621, the resultant force of the urging force due to the fuel pressure in the first back pressure chamber 62 and the urging force due to the spring 623 is the fuel pressure in the valve chamber 61. Therefore, the first valve body 7 moves in a direction to open the high pressure port 611, and high pressure fuel is supplied from the high pressure port 611 to the valve chamber 61.

  When the solenoid valve 52 opens the orifice 621, the fuel pressure in the first back pressure chamber 62 decreases. When the fuel pressure decreases from a predetermined value, the resultant force of the urging force due to the fuel pressure in the first back pressure chamber 62 and the urging force due to the spring 623 becomes relatively weaker than the urging force due to the fuel pressure in the valve chamber 61. The first valve body 7 moves in a direction to close the high pressure port 611, closes the high pressure port 611, and the supply of high pressure fuel to the valve chamber 61 stops.

  After the solenoid valve 52 opens the orifice 621, the first valve body 7 moves to the first back pressure chamber 62 side, and at the same time, the fuel in the valve chamber 61 flows into the first back pressure chamber 62 via the communication passage 73. To do. Further, the fuel is discharged to the first return passage 98 through the orifice 621. That is, when the solenoid valve 52 opens the orifice 621, not only the first back pressure chamber 62 but also the fuel pressure in the valve chamber 61 is reduced. Not only the fuel pressure in the first back pressure chamber 62 but also the fuel pressure in the valve chamber 61 can be controlled only by controlling the opening and closing of the orifice 621 with one electromagnetic valve 52. It is not necessary to prepare a separate device for controlling the fuel pressure in the valve chamber 61, and the fuel injection device 1 can be simplified.

  Since the orifice 74 is provided in the communication path 73, the fuel pressure lowering speeds of the first back pressure chamber 62 and the valve chamber 61 are different. Specifically, the fuel pressure decreasing speed of the valve chamber 61 is slower than the fuel pressure decreasing speed of the first back pressure chamber 62.

  The second valve body 8 has a second valve body portion 81 accommodated in the valve chamber 61 and a second valve body portion 81 having a smaller outer diameter than the second valve body portion 81 and is slidable in the axial direction on the second cylinder portion 615. A sliding portion 83 is provided. The outer diameter of the second valve body portion 81 is smaller than the inner diameter of the valve chamber 61 on the large diameter portion side. The outer diameter of the second valve body 81 is such that when the second valve body 8 moves downward and comes into contact with the lower end surface 617 of the valve chamber 61, the low pressure port 612 formed on the lower end surface 617 is covered. It is the size that is seen.

  The lower end surface 82 of the second valve body 81 is formed with an inner peripheral contact portion 821 that protrudes toward the lower end surface 617 of the valve chamber 61 and an outer peripheral contact portion 822. The inner peripheral contact portion 821 corresponds to the first contact portion described in the claims, and the outer peripheral contact portion 822 corresponds to the second contact portion described in the claims. These contact portions 821 and 822 are formed in an annular shape when the lower end surface 82 of the second valve body portion 81 is viewed from the axial direction (see FIG. 3). A lower end surface 617 of the valve chamber 61 functions as a valve seat portion of the second valve body portion 81.

  When the second valve body 81 abuts the lower end surface 617, the inner peripheral abutment portion 821 is arranged on the lower end surface 617 on the outer peripheral side of the second sliding portion 83 and on the inner peripheral side of the low pressure port 612. It is formed at a position where it abuts. The outer peripheral abutment portion 822 is formed at a position on the outer peripheral side of the low pressure port 612 and in contact with the lower end surface 617 on the inner peripheral side of the control port 613.

  FIG. 4 shows the lower end surface 617 of the valve chamber 61. Of the two broken lines illustrated in FIG. 4, the broken line on the inner peripheral side indicates the position where the inner peripheral contact part 821 contacts, and the broken line on the outer peripheral side indicates the position where the outer peripheral contact part 822 contacts. .

  When the second sliding portion 83 is slidably accommodated in the second cylinder portion 615, the second back pressure chamber 63 formed by the lower end surface of the second sliding portion 83 and the inner wall of the second cylinder portion 615. Is formed. Since the second back pressure chamber 63 is connected to the second control pressure supply passage 97 that communicates with the high pressure chamber 43, the high pressure fuel of the common rail 2 is supplied.

  The second valve body 8 is urged in the direction to open the low pressure port 612 by the fuel pressure in the second back pressure chamber 63, and the high pressure port 611 generated in the first valve body 7 and the fuel pressure in the valve chamber 61. The low pressure port 612 is biased in the direction of closing the low pressure port 612 by the biasing force in the direction of opening the low pressure port.

  As shown in FIG. 2, in the state where the solenoid valve 52 closes the orifice 621, the high pressure port 611 is opened as described above, so that the fuel pressure in the valve chamber 61 is substantially equal to the high pressure fuel in the common rail 2. Same pressure. Therefore, the fuel pressure in the valve chamber 61 is substantially the same as the fuel pressure in the second back pressure chamber 63.

  The size of the second valve body 8 is set so that, in this pressure state, the urging force in the direction of closing the low pressure port 612 is stronger than the urging force in the direction of opening. That is, the diameter of the outer peripheral contact portion 822 is made larger than the diameter of the second sliding portion 83. As a result, when the fuel pressure in the valve chamber 61 is substantially the same as the fuel pressure in the second back pressure chamber 63, the second valve body 8 can maintain the low pressure port 612 closed.

  In the state shown in FIG. 2, the first valve body 7 presses the second valve body 8 in a direction to close the low pressure port 612, so that the inner peripheral side and outer peripheral side contact portions 821, 822 of the second valve body 8. Strongly adheres to the lower end surface 617.

  As described above, when the solenoid valve 52 opens the orifice 621 and the first valve body 7 moves in the direction (upward) closing the high-pressure port 611, the fuel in the valve chamber 61 passes through the communication path 73 to the first return path. The fuel pressure in the valve chamber 61 begins to gradually decrease. When this fuel pressure is reduced from a predetermined value, the biasing force due to the fuel pressure in the valve chamber 61 becomes relatively weaker than the biasing force due to the fuel pressure in the second back pressure chamber 63, so that the second valve body 8 has a low pressure. It moves in the direction of opening the port 612, opens the low pressure port 612, and the fuel in the valve chamber 61 is discharged to the second return passage 99.

  The operation of the fuel injection device 1 of the present embodiment will be described based on FIG. 5 with the operation of the three-way switching valve 51 as the center.

  FIG. 5A shows a first state of the three-way switching valve 51, that is, a state in which the high pressure port 611 is opened and the low pressure port 612 is closed. In this state, the common rail 2 and the pressure increase control chamber 45 communicate with each other, the pressure increasing device 4 is not operated, and fuel pressure is not increased (see FIG. 1).

  As shown in FIG. 5B, when the solenoid valve 52 is operated to open the orifice 621, the fuel in the first back pressure chamber 62 flows out into the first return passage 98, and the fuel pressure in the first back pressure chamber 62 is reached. Decreases. When the fuel pressure decreases from a predetermined value, the first valve body 7 moves upward and closes the high pressure port 611. At the same time that the first valve body 7 starts to move upward, the fuel in the valve chamber 61 is discharged to the first return passage 98 via the communication passage 73, and the fuel pressure in the valve chamber 61 decreases with a delay.

  As shown in FIG. 5C, when the fuel pressure in the valve chamber 61 decreases from a predetermined value, the second valve body 8 moves upward and opens the low pressure port 612. As a result, the fuel in the pressure increase control chamber 45 is discharged to the second return passage 99 through the valve chamber 61, and the pressure increase device 4 starts to increase the pressure in the pressure increase chamber 44. The increased fuel is supplied to the nozzle 3, and the fuel is injected from the injection hole 31.

  In the present embodiment, when the orifice 621 is opened by the electromagnetic valve 52 as described above, the fuel pressure decreasing speed of the valve chamber 61 can be delayed from the fuel pressure decreasing speed of the first back pressure chamber 62. . Thereby, the time when the first valve body 7 closes the high pressure port 611 and the time when the second valve body 8 opens the low pressure port 612 can be shifted. Specifically, in the transition period in which the three-way switching valve 51 is switched from the first state to the second state, the first valve body 7 first closes the high-pressure port 611 and then the second valve body 8 is low-pressure. Port 612 is opened.

  Thereby, in the transition period, the period in which both the high pressure port 611 and the low pressure port 612 are open can be abolished, and the energy loss due to the high pressure fuel in the common rail 2 being discharged to the fuel tank 22 can be eliminated. Can be suppressed.

  When the second valve body 8 moves further upward, the communication passage 73 of the first valve body 7 is closed, and the fuel in the valve chamber 61 is further discharged to the first return passage 98 via the communication passage 73. Can be suppressed. Accordingly, the fuel in the valve chamber 61 is discharged only from the second return passage 99, and the amount of fuel discharged from the pressure increase control chamber 45 to the fuel tank 22 can be limited. As a result, the gradient of the fuel pressure increased by the pressure booster 4 becomes too large, and the deterioration of the exhaust gas performance due to the increase in the fuel injection rate at the initial stage of injection can be suppressed.

  As shown in FIG. 5D, when the orifice 621 is closed by the solenoid valve 52 to stop fuel injection from the nozzle 3, high pressure fuel flows from the common rail 2 into the first back pressure chamber 62, and the first The fuel pressure in the back pressure chamber 62 rises again. The first valve body 7 starts to move downward and opens the high-pressure port 611 again. At the same time, the second valve body 8 is also pushed by the first valve body 7 and begins to move downward. Then, the second valve body 8 closes the low pressure port 612. As a result, the fuel flows again from the common rail 2 into the pressure increase control chamber 45, the fuel pressure increase by the pressure increase device 4 stops, and the fuel injection stops.

  In the present embodiment, the second valve body 81 of the second valve body 8 contacts the outer peripheral side of the lower end surface 617 of the valve chamber 61 with respect to the second cylinder part 615 and the inner peripheral side of the low pressure port 612. An inner peripheral side abutting portion 821 that contacts is formed. As a result, in the state of FIGS. 5A, 5B, and 5D, the second back is interposed through the sliding gap between the second sliding portion 83 and the second cylinder portion 615. It is possible to suppress the high-pressure fuel in the pressure chamber 63 from flowing out into the second return passage 99, and to suppress the generation of energy loss when the second valve body 8 closes the second return passage 99.

  Further, the inner and outer contact portions 821 and 822 are formed so as to protrude in the same direction from the lower end surface 617 of the second valve body portion 81, so that the second valve body 8 is located downward. The high pressure fuel in the second back pressure chamber 63 can be prevented from flowing out into the second return passage 99 through the sliding gap, and at the same time, the fuel in the valve chamber 61 can enter the second return passage 99. The outflow can also be suppressed.

  In the present embodiment, the three-way switching valve 51 that can suppress the occurrence of energy loss when the second valve body 8 closes the second return passage 99 is used as a valve that drives the pressure booster 4 of the fuel injection device 1. used. Thereby, generation | occurrence | production of the energy loss of the fuel injection apparatus 1 was able to be suppressed. As a result, it is possible to suppress an increase in fuel consumption of the engine on which the fuel injection device 1 is mounted.

  In general, the time during which the pressure booster 4 is not operating is much longer than the time during which the pressure booster 4 is operating. In the present embodiment, when the three-way switching valve 51 is in the first state, the pressure increasing device 4 stops the pressure increase of the fuel. For this reason, the suppression effect of generation | occurrence | production of the energy loss of the three-way switching valve 51 can be exhibited over a long time.

(Other embodiments)
FIG. 6 shows another embodiment of the three-way switching valve 51 according to this embodiment. In addition, the same code | symbol is attached | subjected to the component substantially the same as the said embodiment.

  In this other embodiment, the lower end surface 617a of the valve chamber 61, which is the surface with which the inner and outer contact portions 821a and 822a formed on the second valve body 8 are in contact, is the center of the second cylinder portion 615. It becomes the surface which inclines toward. Accordingly, the lower end surface 82a of the second valve body portion 81a is also inclined following the inclined surface.

It is a figure which shows the whole structure of the fuel-injection apparatus using the three-way switching valve by one Embodiment of this invention. It is sectional drawing of the three-way switching valve by one Embodiment of this invention. It is sectional drawing of the III-III line | wire in FIG. It is sectional drawing of the IV-IV line in FIG. (A)-(d) is a figure explaining operation | movement of the three-way switching valve by one Embodiment of this invention. It is sectional drawing of the three-way switching valve by other embodiment of one embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel injection device, 2 Common rail (high pressure source), 22 Fuel tank (low pressure source), 3 Nozzle, 31 Injection hole, 32 Needle, 4 Pressure increase device (fluid device), 41 Pressure increase piston, 42 Cylinder, 43 High pressure chamber , 44 Pressure increase chamber, 45 Pressure increase control chamber (control room), 5 Control section, 51 3-way switching valve, 52 Solenoid valve, 6 Body, 61 Valve chamber, 611 High pressure port (opening of high pressure passage), 612 Low pressure Port (opening of low pressure passage), 613 control port, 616 first valve seat, 617 lower end surface, 62 first back pressure chamber, 63 second back pressure chamber, 7 first valve body, 71 first valve body portion , 72 1st sliding part, 73 communication path, 74 orifice, 8 2nd valve body, 81 2nd valve body part, 82 lower end surface, 821 inner peripheral side contact part (first contact part), 822 outer peripheral side Abutting part (second abutting part), 83 second sliding part, 9 High pressure fuel supply passage, 91 Injection control passage, 93 Fuel supply passage, 94 Pressure increase control passage (control passage), 95 First control pressure supply passage, 96 Control fuel supply passage, 97 Second control pressure supply passage, 98 1 return passage, 99 2nd return passage (low pressure passage)

Claims (6)

A three-way switching valve that switches between a first state in which high-pressure fluid from a high-pressure source is supplied to a control chamber of a fluid device and a second state in which high-pressure fluid in the control chamber is discharged to a low-pressure source;
A body having a high-pressure passage communicating with the high-pressure source, a control passage communicating with the control chamber, and a valve chamber opening the low-pressure passage communicating with the low-pressure source;
A first valve body that opens and closes an opening of the high-pressure passage, wherein one end portion is accommodated in the valve chamber, and the other end portion flows in the high-pressure fluid of the high-pressure source biased toward the one end portion. The body is accommodated in a first back pressure chamber formed on the body, and a side wall between the one end and the other end is slidably supported by the body, and the fluid pressure in the first back pressure chamber is A first valve body that moves to the first back pressure chamber side and closes the opening of the high-pressure passage when lowered from a predetermined value;
A second valve body that opens and closes an opening of the low-pressure passage, the high-pressure fluid of the high-pressure source into which one end is housed in the valve chamber and the other end is urged toward the one end; Housed in a second back pressure chamber formed in the body, the side wall between the one end and the other end is slidably supported by the body, and the pressure of the fluid in the valve chamber decreases from a predetermined value. Then, the second valve body that moves to the valve chamber side and opens the opening of the low-pressure passage,
In the transition period in which the first state is switched to the second state, the second valve body is adjusted by adjusting the pressure of the fluid in the first back pressure chamber and the valve chamber. A three-way switching valve that closes the opening of the high-pressure passage and then opens the opening of the low-pressure passage;
When the second valve body closes the opening of the low-pressure passage, the second valve body, between the sliding portion of the second valve body and the body, and the opening of the low-pressure passage, A first abutting portion that abuts against the inner wall of the valve chamber as the second valve body moves in the axial direction and prevents a fluid flow from the sliding portion to the opening of the low-pressure passage is provided. A three-way switching valve. The first valve body and the second valve body are arranged in the body so that the respective central axes of the first valve body and the second valve body substantially coincide with each other,
The first valve body, when in the second state, presses the second valve body in a direction in which the first contact portion is pressed against the inner wall of the valve chamber. The three-way switching valve described. The second valve body has a valve body portion accommodated in the valve chamber, and a sliding portion that is smaller in diameter than the valve body portion and is slidably supported by the body,
The first contact portion protrudes toward the inner wall of the valve chamber where an opening of the low-pressure passage is formed on an end surface of the valve body portion on the sliding portion side, and the end surface is When viewed from the axial direction of the second valve body, it is formed so as to surround the sliding portion,
Further, the end face of the valve body portion is on the inner wall of the valve chamber on the outer peripheral side of the first contact portion and between the opening of the low pressure passage and the opening of the control passage. 3. The three-way switching valve according to claim 1, wherein a second abutting portion that abuts is formed so as to protrude toward the inner wall of the valve chamber.   The three-way switching valve according to any one of claims 1 to 3, wherein the first valve body is formed with a communication path that communicates the first back pressure chamber and the valve chamber. .   In the transition period in which the first passage changes from the first state to the second state, the fluid pressure in the valve chamber decreases from a predetermined value, and the second valve body opens the opening of the low pressure passage. The three-way switching valve according to claim 4, wherein the three-way switching valve is closed by the second valve body after being opened. A fuel injection device comprising the three-way switching valve according to any one of claims 1 to 5,
A nozzle having a nozzle hole at the tip and injecting fuel from the nozzle hole;
A pressure-increasing chamber into which fuel to be supplied to the nozzle flows, a pressure-increasing piston to be supplied to the nozzle by increasing the pressure of the fuel in the pressure-increasing chamber, and a control in which fluid for controlling the operation of the pressure-increasing piston flows in and out A pressure intensifying device having a chamber,
The control passage of the three-way switching valve communicates with the control chamber of the pressure booster, and the three-way switching valve switches the first state and the second state, thereby causing the high pressure Supplying high-pressure fuel as the high-pressure fluid of the source to the control chamber, discharging the high-pressure fuel of the control chamber to the low-pressure source, and driving or stopping the pressure increasing device. A fuel injection device.

Images