JP3892178B2 - Jet pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a jet pump used in a fuel suction device for a fuel tank in an internal combustion engine such as an automobile.
[0002]
[Prior art]
A conventional example of a fuel suction device equipped with a jet pump will be described with reference to FIGS. 5 is a schematic sectional view of the fuel suction device, and FIG. 6 is a sectional view of the jet pump.
[0003]
In FIG. 5, the inside of the fuel tank 101 is divided into a main chamber 103 and a sub chamber 104 by forming a bulging portion 101a at the bottom thereof. In the main chamber 103, a feed pipe 110, a return pipe 112 and a transfer pipe 113 are arranged in the fuel tank 101. A filter 111 is attached to the inlet of the feed pipe 110.
[0004]
By driving a fuel pump (not shown) disposed outside the fuel tank 101, the fuel in the main chamber 103 is filtered by the filter 111 and sent to the internal combustion engine (not shown) via the feed pipe 110. Be paid. The return pipe 112 discharges fuel that is not consumed by the internal combustion engine into the fuel tank 101 through the jet pump 120.
[0005]
As shown in FIG. 6, the jet pump 120 includes a pump body 121 in which the chamber 122, the throttle portion 123, and the throat portion 124 are integrated, a lid body 130 in which the nozzle 131, the introduction port 132, and the suction port 135 are integrated. Is unitized.
[0006]
The return pipe 112 is connected to the introduction port 132 in communication. A nozzle 131 continuing below the introduction port 132 is projected into the chamber 122. In addition, a throttle portion 123 is formed below the nozzle 131 of the chamber 122. A throat portion 124 is formed below the throttle portion 123.
[0007]
A suction port 135 communicates with the chamber 122. One end of the transfer pipe 113 is connected to the suction port 135 in communication. As shown in FIG. 5, the other end of the transfer pipe 113 is disposed near the bottom of the sub chamber 104.
[0008]
The lid 130 is formed with a relief port 133 that penetrates the introduction port 132 in the radial direction. The lid body 130 is formed with a cylindrical portion 134 that forms substantially the same axis as the relief port 133 outside the introduction port 132. A relief valve 150 that opens when the pressure in the introduction port 132 becomes constant and discharges the fuel in the introduction port 132 to the main chamber 103 is incorporated in the cylindrical portion 134. The relief valve 150 includes a casing 154 inserted into the cylindrical portion 134, a valve body 151 that opens and closes the relief port 133, and a spring 152 that biases the valve body 151 in a closing direction.
[0009]
In the fuel suction device having the jet pump 120, when the fuel pump 6 (not shown) is driven, the fuel in the main chamber 103 is filtered by the filter 111 and passed through the feed pipe 110 as described above. (Not shown). The fuel that is not consumed by the internal combustion engine is discharged as return fuel into the fuel tank 101 via the return pipe 112 and the jet pump 120.
[0010]
In addition, since the introduction port 132 of the jet pump 120 is connected to the end of the return pipe 112, the return fuel is sent from the nozzle 131 of the jet pump 120 to the throttle portion 123 and the throat portion 124 by the discharge pressure of the fuel pump 6. It spouts towards. For this reason, a negative pressure is generated around the nozzle 131 in the chamber 122. The negative pressure causes the fuel in the sub chamber 104 (also referred to as transfer fuel) to be sucked into the chamber 122 via the transfer pipe 113 and the suction port 135, and the flow velocity is increased by the throttle portion 123 together with the jet flow from the nozzle 131. Then, it is discharged from the throat portion 124 into the main chamber 103. As a result, the transfer fuel is transferred into the main chamber 103 as the return fuel is discharged into the main chamber 103 of the fuel tank 101.
[0011]
By the way, when the back pressure by the return fuel in the introduction port 132 (including the return pipe 112) rises above a certain value, the relief valve 150 provided in the relief port 133 is opened, and the fuel in the introduction port 132 is discharged. By discharging into the main chamber 103, an increase in back pressure due to the return fuel is prevented.
[0012]
The jet pump 120 as described above is disclosed in, for example, Japanese Patent Laid-Open No. 63-85254.
[0013]
[Problems to be solved by the invention]
According to the jet pump 120 described above, as shown in FIG. 6, the relief throttle diameter of the relief port 133 (corresponding to the hole diameter of the casing 154) φD_RIs set approximately equal to the inner diameter of the introduction port 132. For this reason, when the relief valve 150 is opened, the back pressure due to the return fuel rapidly decreases, and the transfer flow rate of the transfer fuel in the sub chamber 104 through the suction port 135 drops sharply.
[0014]
Further, when the relief valve 150 is in an open failure, more than half of the return fuel is discharged through the relief port 133 and the return fuel is difficult to be ejected from the nozzle 131. Therefore, the transfer fuel from the sub chamber 104 is sucked into the main chamber 103 through the suction port 135. Cannot be transferred. For this reason, when the fuel in the main chamber 103 is exhausted, an engine stall due to running out of fuel occurs despite the fuel remaining in the sub chamber 104.
[0015]
In order to solve the above problem, the relief aperture diameter φD_RIt is conceivable to reduce. However, the relief diameter φD_RIs unduly small, and the total aperture diameter φD between the nozzle and the relief port_TIf the value is made smaller, the maximum flow rate of the return fuel cannot be exhausted from the nozzle 131 and the relief port 133, leading to a problem that the back pressure due to the return fuel rises excessively.
[0016]
The present invention has been made in order to solve the above-described problems, and the problem to be solved by the present invention is to prevent the back pressure from being increased due to the introduced liquid, while the transfer flow rate of the transfer liquid is abrupt. An object of the present invention is to provide a jet pump capable of suppressing a change and transferring a transfer liquid even when a relief valve is open.
[0017]
[Means for Solving the Problems]
The invention of claim 1 that solves the above-described problem is an intake port for introducing an introduction liquid, a nozzle formed at a terminal portion of the introduction port, and a suction for sucking a transfer liquid by the action of the introduction liquid ejected from the nozzle A jet pump comprising a port and a relief valve that discharges the introduced liquid introduced into the introduction port through the relief port when the pressure in the introduction port becomes a certain level or more,
The nozzle diameter of the nozzle is φD_N, The relief aperture diameter of the relief port is φD_R, The total aperture diameter of the nozzle and the relief port is φD_TWhen
Relief diameter φD_RThe
Nozzle throttle diameter φD set according to requirements such as flow rate performance_NAnd total throttle diameter φD capable of discharging the maximum flow rate of the introduced liquid_TIt is characterized in that it is set within a range not less than a value obtained based on the minimum value of the above and below a value at which the transfer liquid of a predetermined flow rate can be transferred by the introduction liquid of the minimum flow rate when the relief valve fails to open. It is a jet pump.
[0018]
With this configuration, the introduction liquid introduced from the introduction port is ejected from the nozzle, whereby the transfer liquid from the suction port is sucked. Further, when the back pressure due to the introduced liquid rises above a certain value, the relief valve is opened and the introduced liquid is discharged through the relief port, thereby preventing the back pressure from being increased due to the introduced liquid.
[0019]
Also, the nozzle aperture diameter φD of the nozzle_NIs set according to demands such as flow performance, and the total throttle diameter φD between the nozzle and the relief port_TIs set to be equal to or greater than the minimum value capable of discharging the maximum flow rate of the introduced liquid. For this reason, even if the introduction liquid having the maximum flow rate is introduced into the introduction port, an increase in the back pressure due to the introduction liquid is prevented.
[0020]
Relief diaphragm diameter φD_RIs the total aperture diameter φD_TWhen is the minimum value,
φD_R= (ΦD_T ²-ΦD_N ²)^1/2
It is set to be equal to or greater than the minimum value obtained in. For this reason, the total aperture diameter φD_TIs greater than the minimum value capable of discharging the maximum flow rate of the introduced liquid, and the relief throttle diameter φD_RIs less than the minimum value, the introduced fluid can be discharged through the relief port by opening the relief valve, and even if the maximum amount of introduced liquid is introduced into the introduction port, the back pressure is prevented from increasing due to the introduced liquid. Is done.
[0021]
Furthermore, the relief aperture diameter φD_RHowever, the value is set to a value that allows the transfer liquid at a predetermined flow rate to be transferred by the introduction liquid at the minimum flow rate when the relief valve fails to open. For this reason, when the relief valve opens, the transfer liquid of the predetermined flow rate can be transferred by the introduction liquid of the minimum flow rate, and the situation that the transfer liquid cannot be transferred is avoided.
[0022]
Therefore, while preventing an increase in the back pressure due to the introduced liquid, it is possible to suppress a rapid change in the transfer flow rate of the transfer liquid and to transfer the transfer liquid even when the relief valve is open.
[0023]
According to a second aspect of the present invention, the return fuel from the pressure regulator is introduced into the introduction port, and the transfer fuel transferred from the sub chamber of the fuel tank of the internal combustion engine to the main chamber is sucked in from the suction port. This is a jet pump.
[0024]
If comprised in this way, the fall of the pressure regulation performance by the abnormal pressure of a pressure regulator can be prevented by preventing the raise of the back pressure by return fuel. Further, since the transfer fuel can be transferred even when the relief valve is open, a continuous operation of the internal combustion engine when the relief valve is open can be realized. This is effective, for example, when the automobile is evacuated in a jet pump used for an internal combustion engine of the automobile.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, after describing a fuel suction device equipped with a jet pump, the main part of the jet pump will be described in detail.
[0026]
In FIG. 1 showing a schematic cross-sectional view of a fuel suction device equipped with a jet pump, the interior of a fuel tank 1 of an internal combustion engine is divided into a main chamber 3 and a sub chamber 4 by a sub tank 2. In the main chamber 3, a fuel pump 6, a fuel filter 7, a pressure regulator 8, and a jet pump 20 are arranged in a united state.
[0027]
A feed pipe 10 that feeds fuel to the delivery pipe 9 is connected to the pressure regulator 8 in a state of penetrating the inside and outside of the fuel tank 1. The pressure regulator 8 is connected to a return pipe 12 that supplies surplus fuel (also referred to as return fuel) to the jet pump 20. The jet pump 20 is connected to a transfer pipe 13 that sucks fuel in the sub chamber 4 (also referred to as transfer fuel). The inlet 13 b of the transfer pipe 13 is disposed near the bottom of the sub chamber 4.
[0028]
By driving the fuel pump 6, the fuel in the main chamber 3 is pumped up and filtered by the fuel filter 7, and then fed from the pressure regulator 8 to the delivery pipe 9 via the feed pipe 10. The fuel supplied to the delivery pipe 9 is injected from each injector 15 into each cylinder of an engine (also referred to as an internal combustion engine) 16. Return fuel from the pressure regulator 8 is discharged into the main chamber 3 of the fuel tank 1 through the return pipe 12 and the jet pump 20.
[0029]
Next, the jet pump 20 will be described with reference to the cross-sectional view of FIG. The jet pump 20 has a pump body 21 in which the chamber 22, the throttle portion 23 and the throat portion 24 are integrated, an upper connector 30 in which the nozzle 31, the introduction port 32 and the relief port 33 are integrated, and a suction port 41. The side connection body 40 is unitized. Hereinafter, the upper connector 30, the pump body 21, and the side connector 40 will be described in this order.
[0030]
The upper connection body 30 is formed in a substantially tubular shape, and has an introduction port 32 penetrating in the axial direction (the vertical direction in the figure). A nozzle 31 is formed at a terminal portion, that is, a lower end portion of the introduction port 32, and the nozzle 31 projects into the chamber 22 of the pump main body 21. A return pipe 12 (see FIG. 1) communicating with the introduction port 32 is connected to the upper end of the upper connector 30 via a quick connector 12a.
[0031]
A relief port 33 that penetrates the introduction port 32 in the radial direction is formed at the center of the upper connector 30. The upper connection body 30 is formed with a cylindrical portion 34 that is substantially in the same axis as the relief port 33 outside the introduction port 32. A relief valve 50 that opens when the pressure in the introduction port 32 becomes constant and discharges the fuel in the introduction port 32 to the main chamber 3 (see FIG. 1) is incorporated in the cylindrical portion 34.
[0032]
The relief valve 50 is attached to the cylindrical portion 34 by heat caulking or the like, and prevents the spring 52 from coming off. The valve body 51 opens and closes the relief port 33, the spring 52 biases the valve body 51 in the closing direction. And a cap 53. The cylindrical portion 34 is formed with an opening hole 34a penetrating in the radial direction. The opening area of the opening hole 34 a is formed larger than the opening area of the relief port 33.
[0033]
A pump body 21 formed in a substantially tubular shape is coupled to the lower part of the upper connection body 30 by ultrasonic welding or the like. A chamber 22 that includes the nozzle 31 and can discharge liquid is formed in the upper portion of the pump body 21. In the substantially central part of the pump main body 21, a throttle part 23 is formed which is located below the nozzle 31 and communicates with the chamber 22. A throat portion 24 extending in the axial direction is formed in the lower portion of the pump body 21, following the throttle portion 23. Note that the throat portion 24 has a caliber that gradually increases in diameter from a small-diameter tube portion continuous with the lower end portion of the throttle portion 23 to a large-diameter tube portion at the lower end portion.
[0034]
A side connector 40 formed in an almost elbow shape is coupled to the upper portion of the pump body 21 by ultrasonic welding or the like. The side connector 40 forms a substantially L-shaped suction port 41. The suction port 41 is in communication with the chamber 22. A transfer pipe 13 (see FIG. 1) communicating with the suction port 41 is connected to an upper end portion of the side connection body 40 via a quick connector 13a.
[0035]
A fuel reflector 28 is attached to the lower end of the throat portion 24 by heat caulking or the like. The upper surface of the fuel reflector 28 is a flat surface orthogonal to the axis of the throat portion 24. A fuel discharge port 25 that opens in the radial direction of the throat portion 24 is formed on the side wall of the lower end portion of the throat portion 24.
[0036]
In the fuel suction device provided with the jet pump 20, when the fuel pump 6 is driven, the fuel in the main chamber 3 is pumped up and filtered by the fuel filter 7 as described above, and then from the pressure regulator 8. It is fed to the delivery pipe 9 via the feed pipe 10. The fuel supplied to the delivery pipe 9 is injected from each injector 15 to each cylinder of the engine 16. Return fuel from the pressure regulator 8 is discharged into the main chamber 3 of the fuel tank 1 through the return pipe 12 and the jet pump 20.
[0037]
In addition, since the introduction port 32 of the jet pump 20 is connected to the end of the return pipe 12, the return fuel flowing through the return pipe 12 due to the discharge pressure of the fuel pump 6 is throttled from the nozzle 31 of the jet pump 20. 23 and the throat portion 24 are ejected. For this reason, a negative pressure is generated around the nozzle 31 in the chamber 22. Due to the generated negative pressure, the transferred fuel in the sub chamber 4 is transferred into the chamber 22 through the transfer pipe 13 and the suction port 41, and the flow velocity is increased by the throttle 23 together with the jet flow from the nozzle 31, The fuel is discharged from the fuel discharge port 25 into the main chamber 3 through the throat portion 24. Thereby, the transfer fuel is discharged into the main chamber 3 of the fuel tank 1 together with the return fuel. The return fuel corresponds to the introduction liquid referred to in this specification, and the transfer fuel corresponds to the transfer liquid referred to in this specification.
[0038]
Further, when the fuel that has passed through the throat portion 24 is discharged from the fuel discharge port 25, the fuel is reflected by the upper surface of the fuel reflector 28, thereby forming a jet liquid film that blocks the fuel discharge port 25. The This jet liquid film prevents the negative pressure leakage through the fuel discharge port 25, so that the suction force acting on the transferred fuel is improved. The fuel in which the jet liquid film is formed is quickly discharged from the fuel discharge port 25.
[0039]
By the way, when the back pressure due to the return fuel in the introduction port 32 (including the return pipe 12) rises above a certain value, the relief valve 50 is opened, and the return fuel flows into the relief port 33 and the cylindrical portion 34. By being discharged into the main chamber 3 through the hollow portion and the opening hole 34a, an increase in back pressure due to the return fuel is prevented. As a result, an increase in fuel pressure on the supply side of the pressure regulator to the engine can be prevented.
[0040]
Next, the main part of the jet pump 20 will be described in detail. In FIG. 2, the nozzle aperture diameter of the nozzle 31 is φD._N(Mm), relief relief diameter of relief port 33 is φD_R(Mm), the total aperture diameter of the nozzle 31 and the relief port 33 is φD_T(Mm). In FIG. 1, the return flow rate of the return fuel flowing through the return pipe 12 is expressed as Q._R(L / h), the back pressure due to the return fuel is P (kPa). In addition, the transfer flow rate of the transfer fuel flowing through the transfer pipe 13 is Q_S(L / h), the head difference between the top height of the transfer pipe 13 and the position of the liquid surface (see FIG. 1) is H (mm). Note that the amount of fuel consumed through the feed pipe 10 is Q_C(L / h). In addition, the pump discharge flow rate discharged from the jet pump 20 is Q_P(L / h).
[0041]
Nozzle aperture diameter φD_NIs set according to requirements such as flow rate performance. For example, nozzle diameter φD_NCan set a predetermined value in consideration of the flow performance of the jet pump 20 and the molding tolerance. The conditions concerning the flow rate performance of the jet pump 20 include, for example, the discharge flow rate of the fuel pump 6 and the required transfer flow rate Q._SReturn flow rate Q_RMaximum back pressure P_MAXEtc. The conditions relating to the molding tolerance include, for example, the amount of misalignment between the nozzle 31 and the throat, and the nozzle aperture diameter φD due to fuel swelling._NChange rate, variation in the opening operation of the relief valve 50, and the like.
[0042]
Subsequently, the total aperture diameter φD_TIs set as follows. That is, the maximum return flow rate Q_REven when the return fuel is discharged from the nozzle 31 and the relief port 33, the back pressure P caused by the return fuel is the maximum back pressure P._MAXSet not to exceed. For example, fuel consumption Q_CThe return flow rate Q is low when the majority of the discharge flow rate of the fuel pump 6 is returned through the return pipe 12._RIs the maximum. Return flow rate Q_RAnd back pressure P and total throttle diameter φD_TIs in the relationship of the characteristic diagram shown in FIG. Therefore, the maximum return flow rate Q_REven if the return fuel is returned, the back pressure P is the maximum back pressure P_MAXTotal aperture diameter φD not exceeding_TShould be set.
[0043]
In FIG. 3, the horizontal axis represents the return flow rate Q._R(L / h), the vertical axis represents the back pressure P (kPa), and each characteristic line represents the total throttle diameter φD._TIs shown. For example, the maximum return flow Q_R166 (L / h), maximum back pressure P due to return fuel_MAXIs 73.5 (kPa), the total aperture diameter φD that satisfies this condition_TNeeds to be set to about φ2.1 (mm) or more according to FIG. That is, the total aperture diameter φD_TIs expressed by a mathematical formula:
φD_T= (ΦD_N ²+ ΦD_R ²)^1/2≧ φ2.1
It becomes.
[0044]
Subsequently, the relief aperture diameter φD_RIs set as follows. That is, relief aperture diameter φD_RThe minimum value is the nozzle aperture diameter φD_NIs preset, the total aperture diameter φD_TDetermined by the minimum value of. For example, nozzle aperture diameter φD_NΦ1.6 (mm), total aperture diameter φD_TWhen the minimum value of φ2.1 (mm),
φD_T= (ΦD_N ²+ ΦD_R ²)^1/2
Substituting each numerical value for,
φD_RNIN= 1.4
It becomes. Therefore, the relief aperture diameter φD_RIs
φD_R≧ 1.4
It becomes.
[0045]
Relief diaphragm diameter φD_RIs set to a value that allows the transfer fuel of a predetermined flow rate to be transferred by the return fuel of the minimum flow rate even if an open failure occurs in the relief valve 50. The predetermined flow rate of the transfer fuel is, for example, the amount of fuel consumed by the engine (internal combustion engine) when the vehicle travels at a low speed. Required minimum flow rate of return fuel (also referred to as required return flow rate) Q required to transfer the head difference H and the transfer fuel of a predetermined flow rate_RHAnd nozzle aperture diameter φD_NIs in the relationship shown in FIG. Therefore, the head difference H and the nozzle aperture diameter φD_NAnd required return flow rate Q_RHFind the minimum flow rate.
[0046]
In FIG. 4, the horizontal axis indicates the head difference H (mm), and the vertical axis indicates the required return flow rate Q._RH(L / h), each characteristic line is the nozzle aperture diameter φD_N(Mm) is shown. For example, the head difference H is 300 (mm), and the nozzle aperture diameter φD_NThe required return flow rate Q that satisfies the conditions of φ1.6 (mm)_RH4 is about 33 (L / h) or more from FIG.
[0047]
In addition, the required return flow rate Q when the relief valve 50 is broken down_RHAnd maximum return flow Q_RAnd nozzle aperture diameter φD_NAnd relief diameter φD_RThe relationship with
Q_RH/ Q_R= ΦD_N ²/ (ΦD_R ²+ ΦD_N ²)
It is.
[0048]
Therefore, the relief aperture diameter φD_RThe maximum value of
φD_R= [(Q_R× φD_N ²/ Q_RH-ΦD_N ²}^1/2
It is calculated from. In this equation, the required return flow rate Q exemplified above_RH33 (L / h), return flow rate Q_RMaximum flow rate of 166 (L / h), nozzle throttle diameter φD_NSubstituting each numerical value of φ1.6 (mm) of
φD_R= Φ3.21
It becomes.
[0049]
Therefore, the relief aperture diameter φD_RIs
φ1.4 ≦ φD_R≦ φ3, 21
Set to.
[0050]
According to the jet pump 20 described above, the nozzle aperture diameter φD of the nozzle 31._NIs set according to the flow rate performance and the like, and the total throttle diameter φD of the nozzle 31 and the relief port 33 is set._TIs set to be equal to or greater than the minimum value that can discharge the maximum flow rate of return fuel. For this reason, even if the return fuel having the maximum flow rate is introduced into the introduction port 32, the back pressure is prevented from increasing due to the return fuel.
[0051]
Relief diaphragm diameter φD_RIs the total aperture diameter φD_TWhen is the minimum value,
φD_R= (ΦD_T ²-ΦD_N ²)^1/2
It is set to be equal to or greater than the minimum value obtained in. For this reason, the total aperture diameter φD_TIs equal to or greater than the minimum value capable of discharging the maximum flow rate of return fuel, and the relief throttle diameter φD_RIs equal to or greater than the minimum value, the return fuel can be discharged through the relief port 33 by opening the relief valve 50. Even if the maximum amount of return fuel is introduced into the introduction port 32, the back pressure of the return fuel is reduced. The rise is prevented.
[0052]
Furthermore, the relief aperture diameter φD_RHowever, it is set below the maximum value at which the transfer fuel at a predetermined flow rate can be transferred by the return fuel at the minimum flow rate when the relief valve 50 is open. For this reason, when the relief valve 50 is in an open failure, the transfer fuel of a predetermined flow rate can be transferred by the return fuel of the minimum flow rate, and the situation where the transfer fuel cannot be transferred is avoided.
[0053]
Therefore, according to the jet pump 20 described above, while preventing an increase in the back pressure due to the return fuel, a rapid change in the transfer flow rate of the transfer fuel is suppressed, and the transfer fuel is transferred even when the relief valve 50 is open. can do.
[0054]
Also, return fuel from the pressure regulator 8 is introduced into the introduction port 32, and the transfer fuel transferred from the sub chamber 4 of the fuel tank 1 of the internal combustion engine to the main chamber 3 is sucked in from the suction port 41, and the above-mentioned fuel into the main chamber 3 is drawn. The jet pump 20 transfers the transfer fuel to the main chamber 3 along with the discharge of return fuel.
[0055]
Therefore, it is possible to prevent an abnormal pressure from being applied to the pressure regulator 8 by preventing the back pressure from increasing due to the return fuel. Further, since the transferred fuel can be transferred even when the relief valve 50 is open, a continuous operation of the internal combustion engine when the relief valve 50 is open can be realized. This is effective, for example, when the automobile is evacuated in the jet pump 20 used in the internal combustion engine of the automobile.
[0056]
The present invention is not limited to the embodiment described above, and can be modified without departing from the gist of the present invention. For example, the jet pump 20 of the present invention is not limited to the one used in the fuel suction device of the fuel tank in the internal combustion engine, but can be used in other liquid suction devices. Moreover, the suction structure of the transfer liquid in the jet pump can be changed as appropriate. Further, the shape of the fuel tank 1 can be changed as appropriate.
[0057]
【The invention's effect】
According to the jet pump of the present invention, while preventing an increase in back pressure due to the introduced liquid, it is possible to suppress a rapid change in the transfer flow rate of the transfer liquid and to transfer the transfer liquid even when the relief valve is open. Can do.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a fuel suction device provided with a jet pump.
FIG. 2 is a cross-sectional view of a jet pump.
FIG. 3 is a characteristic diagram showing a relationship among a return flow rate, a back pressure, and a nozzle diameter.
FIG. 4 is a characteristic diagram showing a relationship among a head difference, a required return flow rate, and a nozzle diameter.
FIG. 5 is a schematic cross-sectional view of a fuel suction device equipped with a conventional jet pump.
FIG. 6 is a cross-sectional view of a conventional jet pump.
[Explanation of symbols]
1 Fuel tank
3 main rooms
4 Subroom
8 Pressure regulator
20 Jet pump
22 chambers
31 nozzles
32 Introduction port
33 Relief Port
41 Suction port
50 relief valve
φD_NNozzle aperture diameter
φD_RRelief diameter
φD_TTotal aperture diameter

Claims (2)

An introduction port for introducing the introduction liquid, a nozzle formed at a terminal portion of the introduction port, a suction port for sucking the transfer liquid by the action of the introduction liquid ejected from the nozzle, and the pressure in the introduction port is not less than a certain level And a relief pump that discharges the introduction liquid introduced into the introduction port through the relief port,
Nozzle aperture diameter [phi] D _N of the nozzle, the relief aperture [phi] D the diameter _R of the relief port when the total aperture diameter of the nozzle and the relief port and [phi] D _T,
The relief aperture diameter [phi] D _R,
Flow rate performance and the like required in accordance with the set nozzle aperture diameter [phi] D _N and the value determined based on the minimum value of introducing a maximum flow rate capable of discharging a total aperture diameter [phi] D _T of the liquid over and opening of the relief valve A jet pump characterized in that it is set within a range that is less than or equal to a value at which a predetermined flow rate of the transfer liquid can be transferred by a minimum flow rate of introduced liquid when a failure occurs. 2. The jet pump according to claim 1, wherein the return fuel from the pressure regulator is introduced into the introduction port, and the transfer fuel transferred from the sub chamber of the fuel tank of the internal combustion engine to the main chamber is sucked in from the suction port.

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