JP2016156287A - pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a prescribed sealing function without deteriorating pump efficiency while preventing breakage or delayed fracture of a screw.SOLUTION: A body 31 partitioning a pump chamber 15 in cooperation with a cylinder 13 and a plunger 14 has a cylindrical seal cylinder part 31b, and the seal cylinder part 31b is arranged in the pump chamber 15. In a pressure-feed process in which fuel in the pump chamber 15 is pressurized, the seal cylinder part 31b is deformed to a radial outer side under the pressure of the fuel in the pump chamber 15, and an outer peripheral surface of the seal cylinder part 31b is pressed onto a cylinder inner wall surface 13f. Accordingly, leakage of the fuel between the pump chamber 15 and a fuel gallery 19 can be prevented by adhesion between the outer peripheral surface of the seal cylinder part 31b and the cylinder inner wall surface 13f.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pump that pressurizes a fluid by changing the volume of a pump chamber by reciprocating movement of a plunger.

  Conventionally, as this type of pump, for example, there is one described in Patent Document 1. In the pump described in Patent Document 1, a plunger is reciprocally disposed in a cylinder, a body (flow path forming member) is disposed at an end of the cylinder, and a pump chamber is formed by the cylinder, the plunger, and the body. It is partitioned. Further, a fixing member (solenoid valve) is screwed into the cylinder, and the cylinder and the body are brought into close contact with each other by the axial force so as to exert a sealing function.

Japanese Patent No. 5240284 JP 2010-223280 A

  However, in the conventional pump, as the set pressure of the fluid to be pressurized increases, the seal surface pressure needs to be increased, and the axial force needs to be set high. As a result, the stress generated in the threaded portion is also increased, and there are concerns such as breakage of the threaded portion and delayed fracture.

  Incidentally, Patent Document 2 describes an injector that injects high-pressure fuel. In the injector described in Patent Document 2, a tip packing having a high-pressure fuel passage and a nozzle body having a high-pressure fuel passage are sandwiched between a retaining nut and a lower body, and the retaining nut and the lower body are screwed together. The tip packing and the nozzle body are brought into close contact by the axial force.

  In addition, a recess is formed in the tip packing so as to extend to the outer peripheral side of the high-pressure fuel passage, and the tip packing shelf is pressed against the nozzle body by the pressure of the high-pressure fuel introduced into the recess to exert a sealing function. It is supposed to let you.

  Thus, since it is not necessary to increase the axial force by increasing the seal surface pressure with the fuel pressure, it is possible to prevent damage to the threaded portion, delayed fracture, and the like.

  If the technical idea of Patent Document 2 (that is, increasing the seal surface pressure by using fluid pressure) is applied to a conventional pump, the outer circumference of the pump chamber is formed on the inner wall surface of the cylinder that defines the pump chamber in the cylinder. It is conceivable to form a recess so as to extend to the side.

  However, when the concave portion is formed in the cylinder, the dead volume of the pump chamber increases by the volume of the concave portion, and the pump efficiency decreases.

  The present invention has been made in view of the above points, and it is an object of the present invention to obtain a predetermined sealing function without reducing pump efficiency and while preventing breakage or delayed destruction of a threaded portion.

  In order to achieve the above object, according to the first aspect of the present invention, a cylinder (13), a plunger (14) disposed in a reciprocating manner in the cylinder, and a pump chamber whose volume is changed by the reciprocating motion of the plunger. (15), a body (31) disposed on one end side of the cylinder and defining the pump chamber in cooperation with the cylinder and the plunger, and a fixing member (32) screwed into the cylinder to fix the body to the cylinder The body has a cylindrical seal cylinder portion (31b) inserted into the pump chamber and pressed against the cylinder inner wall surface (13f) defining the pump chamber in the cylinder by the pressure of the fluid in the pump chamber. To do.

  According to this, a sealing function is obtained by the close contact between the inner wall surface of the cylinder and the seal cylinder part, and at that time, the sealing surface pressure is secured not by the axial force but by the fluid pressure, so it is not necessary to set the axial force high. In addition, it is possible to prevent breakage and delayed destruction of the threaded portion. Moreover, since the dead volume of the pump chamber does not increase, the pump efficiency does not decrease.

  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 typical sectional drawing which shows the pump which concerns on one Embodiment of this invention. It is sectional drawing which expands and shows the principal part of the pump which concerns on one Embodiment.

  An embodiment of the present invention will be described. The pump according to the present embodiment is applied to a fuel supply device that supplies fuel to a compression ignition type internal combustion engine (hereinafter simply referred to as an internal combustion engine). More specifically, the pressure of fuel such as light oil is increased to a common rail. To supply.

  As shown in FIG. 1, the housing 10 is formed with a cam chamber 10 a located on the lower end side thereof, and a housing through hole 10 b in a cylindrical space extending from the cam chamber 10 a toward the upper side of the housing 10. . The spaces in the cam chamber 10a and the housing through hole 10b are filled with lubricating oil for lubricating the cam 12, the slider 17, the cam roller 18 and the like which will be described later.

  A cam shaft 11 driven by an internal combustion engine (not shown) is disposed in the cam chamber 10a, and the cam shaft 11 is rotatably supported by the housing 10. A cam 12 is formed on the cam shaft 11.

  A cylinder 13 made of metal (for example, SCM) is inserted into the housing through hole 10b so as to close the upper end side of the housing through hole 10b.

  The cylinder 13 is formed with a plunger insertion hole 13a in a columnar space, and a columnar plunger 14 is inserted into the plunger insertion hole 13a so as to freely reciprocate.

  The plunger 14, the cylinder 13, and a first body 31 of a solenoid valve 30 described later define a cylindrical space in the pump chamber 15, and the volume of the pump chamber 15 changes as the plunger 14 reciprocates. ing.

  A seat 14a is connected to the lower end of the plunger 14, and the plunger 14 is pressed against the slider 17 by a spring 16 through the seat 14a.

  The slider 17 is formed in a cylindrical shape, and is inserted into the housing through hole 10b so as to reciprocate. A cam roller 18 is rotatably attached to the slider 17, and the cam roller 18 is in contact with the cam 12. When the cam 12 is rotated by the rotation of the cam shaft 11, the plunger 14 is driven to reciprocate together with the sheet 14a, the slider 17 and the cam roller 18.

  An annular fuel gallery 19 is formed in the cylinder 13 for storing fuel to be supplied to the pump chamber 15. The fuel gallery 19 is connected to a fuel tank 41 via a low pressure passage hole 13 b formed in the cylinder 13 and a low pressure fuel pipe 40. In the low-pressure fuel pipe 40, a feed pump 42 that sucks the fuel stored in the fuel tank 41 and discharges it at a low pressure is disposed. The fuel is pumped to the fuel gallery 19 by the feed pump 42.

  The fuel gallery 19 is communicated with the pump chamber 15 through a communication hole 31a formed in a first body 31 of an electromagnetic valve 30 described later.

  The cylinder 13 is formed with a high-pressure passage hole 13 c that always communicates with the pump chamber 15. The pump chamber 15 is connected to the common rail 43 through the high-pressure passage hole 13c, the discharge valve 20, and the high-pressure fuel pipe 45.

  The discharge valve 20 includes a valve body 20a that opens and closes the high-pressure fuel passage, and a spring 20b that biases the valve body 20a in the valve closing direction. The high-pressure fuel pressurized in the pump chamber 15 moves the valve body 20a in the valve opening direction against the urging force of the spring 20b and is pumped to the common rail 43.

  A leak collection groove 21 for collecting fuel leaking from between the plunger 14 and the cylinder 13 is formed on the inner wall of the plunger insertion hole 13a. The leak recovery groove 21 is an annular groove whose diameter is increased on the inner wall of the plunger insertion hole 13 a of the cylinder 13. Further, the opening on the lower side of the leak recovery groove 21 is closed by the cover 22.

  In the leak recovery groove 21, fuel leaks from the pump chamber 15 to the space in the housing through hole 10 b and the cam chamber 10 a through the outer peripheral side of the plunger 14, and from the space in the housing through hole 10 b and the cam chamber 10 a. A plunger seal member 23 for preventing leakage of lubricating oil transmitted to the pump chamber 15 is disposed.

  The leak recovery groove 21 is connected to the fuel tank 41 via a return passage hole 13 d formed in the cylinder 13 and a return fuel pipe 44. As a result, the fuel that has flowed into the leak recovery groove 21 is returned to the fuel tank 41.

  The low-pressure passage hole 13b is connected to the return passage hole 13d through a relief passage hole 13e formed in the cylinder 13.

  In the middle of the relief passage hole 13e, a pressure regulating valve 25 that regulates the maximum pressure in the fuel gallery 19 is disposed.

  The pressure regulating valve 25 includes a valve body 25a that opens and closes the relief passage hole 13e, and a spring 25b that biases the valve body 25a in the valve closing direction. When the pressure in the fuel gallery 19 becomes equal to or higher than a reference pressure (for example, 0.5 MPa), the valve body 25a moves in the valve opening direction against the spring 25b, and the relief passage hole 13e is opened. The fuel on the fuel gallery 19 and the low-pressure passage hole 13b side is returned to the fuel tank 41.

  As shown in FIGS. 1 and 2, the electromagnetic valve 30 includes a substantially cylindrical first body 31 and a substantially cylindrical second body 32. The first body 31 is disposed on one end side of the cylinder 13 and is assembled to the cylinder 13 so as to close the pump chamber 15.

  The first body 31 is made of metal (for example, SCM), and a second body 32 as a fixing member is screwed into the cylinder 13 and fixed to the cylinder 13.

  The first body 31 is formed with a communication hole 31 a having one end communicating with the pump chamber 15 and the other end communicating with the fuel gallery 19.

  In addition, a cylindrical seal cylinder portion 31b that protrudes toward the pump chamber 15 side is formed at the end portion of the first body 31 on the pump chamber 15 side so as to surround the opening portion on the pump chamber 15 side of the communication hole 31a. ing. The seal cylinder portion 31 b is inserted into the pump chamber 15. In addition, the clearance gap between the outer peripheral surface of the seal cylinder part 31b and the cylinder inner wall face 13f which divides the pump chamber 15 in the cylinder 13 is set to several micrometers.

  Further, a ring-shaped groove 31c is formed at an end portion on the pump chamber 15 side of the first body 31 at a position radially outward from the seal cylinder portion 31b. An O-ring 39 is inserted into the groove 31c. The portion where the O-ring 39 is disposed is a portion where the first body 31 is pressed against the cylinder 13 by the axial force of the second body 32 and the two are in close contact with each other.

  The solenoid valve 30 includes a coil 33 that generates a magnetic field when energized, a stator core 34 that generates an attractive force when the coil 33 is energized, an armature 35 that is attracted to the stator core 34 when the coil 33 is energized, and an armature 35. It has an integral rod 35a. The rod 35a is slidably held by the second body 32.

  Further, the electromagnetic valve 30 abuts on the rod 35a, moves integrally with the armature 35 and the rod 35a, and is integrated with the valve body 36 that opens and closes between the communication hole 31a and the pump chamber 15 by press fitting. A first spring 37 that biases the spring seat 36a, the valve body 36, and the spring seat 36a toward the armature 35, and a second spring 38 that biases the armature 35 and the valve body 36 toward the anti-suction side. doing. The valve body 36 is slidably held by the first body 31.

  The operation of the fuel supply apparatus having the above configuration will be described. First, when the coil 33 of the solenoid valve 30 is not energized, the valve body 36 of the solenoid valve 30 is moved to the valve opening position by the urging force of the second spring 38, and the communication hole 31a and the pump chamber 15 are in communication with each other. It has become.

  In the suction process in which the communication hole 31a and the pump chamber 15 communicate with each other and the plunger 14 descends, the low-pressure fuel discharged from the feed pump 42 is supplied to the low-pressure fuel pipe 40, the low-pressure passage hole 13b, The fuel is supplied to the pump chamber 15 through the fuel gallery 19 and the communication hole 31a.

  Next, in the discharge process in which the plunger 14 rises, the plunger 14 attempts to pressurize the fuel in the pump chamber 15. However, since the coil 33 is not energized at the beginning of the start of raising the plunger 14 and the communication hole 31a and the pump chamber 15 communicate with each other, the fuel in the pump chamber 15 passes through the communication hole 31a. It overflows to the gallery 19 side and is not pressurized.

  When the coil 33 is energized during the fuel overflow in the pump chamber 15, the armature 35 is attracted to the stator core 34 against the second spring 38. The valve body 36 is urged by the first spring 37 to follow the armature 35, moves to the valve closing position, and blocks the communication hole 31 a from the pump chamber 15.

  Thereby, the overflow of the fuel to the fuel gallery 19 side is stopped, and pressurization of the fuel in the pump chamber 15 by the plunger 14 is started. Then, the discharge valve 20 is opened by the fuel pressure in the pump chamber 15, and high-pressure fuel is pumped to the common rail 43.

  In the pumping process in which the fuel in the pump chamber 15 is pressurized, the seal cylinder portion 31b receives the high fuel pressure in the pump chamber 15 and deforms radially outward, and the outer peripheral surface of the seal cylinder portion 31b is the cylinder inner wall surface. It is pressed against 13f. Therefore, fuel leakage between the pump chamber 15 and the fuel gallery 19 is prevented by the close contact between the outer peripheral surface of the seal cylinder portion 31b and the cylinder inner wall surface 13f. In addition, the higher the fuel pressure in the pump chamber 15, the higher the surface pressure of the contact portion (that is, the seal portion), and the higher the sealing performance.

  In the operation region where the fuel pressure in the pump chamber 15 is low, a sealing function due to the close contact between the seal cylinder portion 31b and the cylinder inner wall surface 13f cannot be obtained. Therefore, at that time, fuel leakage between the pump chamber 15 and the fuel gallery 19 is prevented by the O-ring 39.

  As described above, according to the present embodiment, a sealing function is obtained by the close contact between the seal cylinder portion 31b and the cylinder inner wall surface 13f, and at this time, the seal surface pressure is not the axial force but the fuel pressure in the pump chamber 15. Therefore, it is not necessary to set the axial force high, and damage to the second body 32 and the threaded portion of the cylinder 13 and delayed destruction can be prevented. Moreover, since the dead volume of the pump chamber 15 does not increase, the pump efficiency does not decrease.

(Other embodiments)
In the above-described embodiment, the present invention is applied to a pump that increases the pressure of fuel such as light oil and supplies it to the common rail. However, the present invention can also be applied to pumps for other uses.

  In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably.

  Further, in the above-described embodiment, it is needless to say that elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where the element is clearly considered to be essential in principle. .

  Further, in the above embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is particularly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to a specific number except for cases.

  In the above embodiment, when referring to the shape, positional relationship, etc. of components, the shape, position, etc., unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to relationships.

13 Cylinder 14 Plunger 15 Pump chamber 31 First body (body)
32 Second body (fixing member)
13f Cylinder inner wall surface 31b Seal cylinder

Claims (2)

A cylinder (13);
A plunger (14) disposed reciprocally in the cylinder;
A pump chamber (15) whose volume is changed by the reciprocation of the plunger;
A body (31) disposed on one end side of the cylinder and defining the pump chamber in cooperation with the cylinder and the plunger;
A fixing member (32) screwed into the cylinder and fixing the body to the cylinder;
The body has a cylindrical seal cylinder portion (31b) inserted into the pump chamber and pressed against a cylinder inner wall surface (13f) defining the pump chamber in the cylinder by the pressure of fluid in the pump chamber. Features a pump.   The pump according to claim 1, wherein an O-ring (39) is disposed at a portion of the cylinder and the body that are in close contact with each other by an axial force of the fixing member.

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