Low-pressure regulator for gas fuel

Abstract

To stabilize regulator outlet pressure in any operational region, in a low-pressure regulator for gas fuel comprising a bypass fuel passage that bypasses an on-off valve.SOLUTION: A low-pressure regulator 1A for gas fuel comprises: a pressure regulating chamber 7 that communicates the inside of a body 2 with a fuel introduction passage 3 and a fuel delivery passage 4; an on-off valve 8 that partitions an atmospheric pressure chamber 5 communicated with the atmosphere by a diaphragm 6, and provided at an opening part of the fuel introduction passage 3; and a bypass fuel passage 10 that bypasses the on-off valve 8 and injects gas fuel from the fuel introduction passage 3 into the pressure regulating chamber 7. At a terminal side opening part of the bypass fuel passage 10, buffer means is arranged to prevent a jet flow of gas fuel from hitting the diaphragm 6 directly while colliding with it and changing its direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a low-pressure regulator for gas fuel, which is used to reduce the pressure of high-pressure gas fuel such as LPG (liquefied petroleum gas) or CNG (compressed natural gas) sent from a pressure vessel to the atmospheric pressure level and send it to a mixer or an injector.

Background Art

[0002] Conventionally, when supplying gas fuel such as LPG or CNG to an engine, the liquid gas fuel filled in a pressure vessel is used as gas fuel whose pressure is reduced and adjusted to about atmospheric pressure by a low-pressure regulator, and this is sent to a mixer or an injector and supplied from an intake pipeline. This is common.

[0003] As such a low-pressure regulator, for example, a low-pressure regulator 1D as shown in FIG. 5 and presented in JP-A-2017-020456 (Patent Document 1) and JP-A-2019-015181 (Patent Document 2) is well-known. Its configuration is such that inside a body 2 in which a fuel introduction passage 3 and a fuel delivery passage 4 are formed, an atmospheric pressure chamber 5 communicating with the atmosphere side and a pressure regulating chamber 7 partitioned from the atmospheric pressure chamber 5 by a diaphragm 6 are formed, and an on-off valve 8 disposed between the fuel introduction passage 3 and the pressure regulating chamber 7 is actuated by a valve lever 9.

[0004] The valve lever 9 is connected to the tip 92 side in a state of being biased by a pressure regulating spring 91 with respect to a rod 63 fixed at the center position of diaphragm plates 61, 62 attached to sandwich the diaphragm 6 at the central portion of the diaphragm 6. Then, by the reciprocating displacement of the diaphragm 6 according to the change in the pressure difference between the pressure regulating chamber 7 side and the atmospheric pressure chamber 5 side, the valve lever 9 swings about a pin 93, and the valve body 81 is separated from or brought into contact with the valve seat 82 to open and close the on-off valve 8, and the pressure of the gas fuel introduced into the pressure regulating chamber 7 is adjusted to a constant pressure at almost the atmospheric pressure level and sent out from the fuel delivery passage 4.

[0005] However, with such low-pressure regulators for gas fuel, in situations where the intake pressure applied to the regulator outlet is small, such as during engine startup or in low-speed / low-opening ranges, it may not be possible to deliver the required engine flow rate. Therefore, as shown in Figure 6, a bypass fuel passage 10 is formed that connects the fuel introduction passage 3 to the pressure regulating chamber 7 without going through the on-off valve 8, and a bypass jet 11 having a throttling structure 111 is provided at its end to inject gas fuel into the pressure regulating chamber 7. This method is widely adopted.

[0006] However, in a low-pressure regulator like the one described above (1D), where the diaphragm 6 is positioned downstream of the bypass fuel passage 10, and where a function to control minute pressures is required, there is a problem that the jet (indicated by the black arrow in the diagram) exiting the bypass jet 11 via the bypass fuel passage 10 directly hits the diaphragm 6, which tends to make the regulator outlet pressure unstable. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2017-020456 [Patent Document 2] Japanese Patent Publication No. 2019-015181 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The present invention aims to solve the above-mentioned problems and to stabilize the regulator outlet pressure in all operating ranges of the engine in a low-pressure regulator for gas fuel equipped with a bypass fuel passage that bypasses the on / off valve. [Means for solving the problem]

[0009] Therefore, the present invention provides a low-pressure regulator for gas fuel, comprising: a body having a fuel introduction passage and a fuel delivery passage formed therein; a back pressure chamber formed within the body and communicating with the atmosphere; a pressure regulating chamber formed within the body and communicating with the fuel introduction passage and the fuel delivery passage; a diaphragm separating the back pressure chamber and the pressure regulating chamber; an on-off valve provided between the fuel introduction passage and the pressure regulating chamber; a valve lever that is biased by a pressure regulating spring and swings due to the reciprocating displacement of the diaphragm to operate the on-off valve; and a bypass fuel passage that bypasses the on-off valve from the fuel introduction passage and communicates with the pressure regulating chamber, and injects gas fuel from a throttling structure at the end side toward the diaphragm, wherein the gas fuel introduced from the fuel introduction passage into the pressure regulating chamber is reduced and adjusted to a predetermined pressure and delivered from the fuel delivery passage, characterized in that a buffering means is provided at the end opening of the bypass fuel passage to cause the gas fuel jet to collide and change its direction so that it does not directly hit the diaphragm.

[0010] In this way, by providing a buffering mechanism at the end of the bypass fuel passage that bypasses the regulator's on-off valve, which causes the gaseous fuel jet to collide with the diaphragm and prevent it from directly hitting it, the impact pressure on the diaphragm from the gaseous fuel jet that has passed through the bypass route of the on-off valve is buffered, minimizing the impact on its pressure regulating function. As a result, the regulator outlet pressure can be easily stabilized in all operating ranges.

[0011] Furthermore, if the buffering means is in the shape of a T-tube that branches the flow path at the end of the straight bypass fuel passage into two perpendicular directions, the gaseous fuel jet can be guided in a direction different from that of the diaphragm by colliding with the end of the straight flow path and branching into two perpendicular directions. This allows for excellent buffering functionality.

[0012] Furthermore, if the buffering means is shaped to branch the flow path at the end of the straight bypass fuel passage into three or more radial branches perpendicular to its axial direction, the gaseous fuel jet can be guided in a direction different from the diaphragm by being branched in multiple perpendicular and radial directions while colliding with the end of the straight flow path, thereby exhibiting an even better buffering function.

[0013] Furthermore, if the buffering means is a shielding plate that causes the jet to collide at a predetermined distance from the opening of the bypass fuel passage, the present invention can be implemented at low cost while using the existing bypass jet as is. [Effects of the Invention]

[0014] According to the present invention, a buffering means is provided at the end of a bypass fuel passage that bypasses the on / off valve, causing the gaseous fuel jet to collide with the diaphragm and prevent it from directly hitting it. This makes it possible to stabilize the regulator outlet pressure in all operating ranges of the engine. [Brief explanation of the drawing]

[0015] [Figure 1] A longitudinal cross-sectional view showing a low-pressure regulator for gas fuel, which is a preferred embodiment of the present invention. [Figure 2] A longitudinal cross-sectional view showing a low-voltage regulator, which is a different embodiment of the present invention. [Figure 3] A longitudinal cross-sectional view showing a low-voltage regulator, which is yet another embodiment of the present invention. [Figure 4] A graph showing the PQ characteristics of discharge flow rate and outlet pressure in the present invention and conventional low-pressure regulators. [Figure 5] A longitudinal cross-sectional view showing a conventional low-voltage regulator. [Figure 6] Figure 5 shows a longitudinal cross-sectional view of the low-voltage regulator, cut from a different direction. [Modes for carrying out the invention]

[0016] Hereinafter, embodiments for implementing the present invention will be described with reference to the drawings.

[0017] FIG. 1 shows a longitudinal sectional view of a low-pressure regulator 1A for gaseous fuel according to this embodiment. Inside a body 2 in which a fuel introduction passage 3 and a fuel delivery passage 4 are formed, an atmospheric pressure chamber 5 communicating with the atmosphere side and a pressure regulating chamber 7 partitioned by the atmospheric pressure chamber 5 and a diaphragm 6 are formed. An on-off valve 8 disposed between the fuel introduction passage 3 and the pressure regulating chamber 7 is operated by a valve lever 9.

[0018] Further, the valve lever 9 is connected to the tip 92 side in a state of being biased by a pressure regulating spring 91 with respect to a rod 63 fixed at the center positions of diaphragm plates 61 and 62 attached with the diaphragm 6 interposed therebetween at the central portion of the diaphragm 6 (see the longitudinal sectional view of the conventional example shown in FIG. 5).

[0019] And, by the reciprocating displacement of the diaphragm 6 according to the change in the pressure difference between the pressure regulating chamber 7 side and the atmospheric pressure chamber 5 side, the valve body 81 is separated from or brought into contact with the valve seat 82 by the swinging operation of the valve lever 9 with a pin 93 as an axis, and the pressure of the gaseous fuel introduced into the pressure regulating chamber 7 is adjusted to a constant pressure at almost the atmospheric pressure level while opening and closing the on-off valve 8, and then sent out from the fuel delivery passage 4. In this respect, it is the same as the low-pressure regulator 1D of the conventional example.

[0020] Furthermore, similar to the above-described conventional example, in order to cope with a situation where the suction pressure on the engine side during low-speed and low-opening operation is weak from the start of engine operation, a bypass fuel passage 10 formed by bypassing the on-off valve 8 from the fuel introduction passage 3 and communicating with the inside of the pressure regulating chamber 7, and a bypass jet 12 attached to the end-side opening of the bypass fuel passage 10 and having a throttle structure portion 121 for ejecting gaseous fuel toward the diaphragm 6 side are provided.

[0021] Furthermore, in the present invention, the low-pressure regulator 1A having the above-described configuration is characterized in that the bypass jet 12, attached to the terminal opening of the bypass fuel passage 10, is a T-shaped tubular structure equipped with lateral discharge passages 122 and 123 that branch the linear flow path at the terminal end of the bypass fuel passage 10 into two paths perpendicular to its axial direction, as a buffering means for causing the gaseous fuel jet to collide and change its direction so that it does not directly hit the diaphragm 6.

[0022] By adopting the above-described configuration in the low-pressure regulator 1A, the jet of gaseous fuel (indicated by the black arrow in the diagram) introduced into the pressure regulating chamber 7 through the bypass fuel passage 10 can be split into two perpendicular streams while colliding at the end of the straight flow path, and guided in a direction different from that of the diaphragm 6. This makes it possible to exhibit an excellent buffering function that minimizes the influence of the gaseous fuel jet on the reciprocating displacement of the diaphragm 6.

[0023] At this time, the jet of gaseous fuel, whose direction has been changed, may strike the surface of the diaphragm plate 61, which is attached on either side of the diaphragm 6. However, this does not pose a problem because it avoids the bulging portion 64, which is relatively susceptible to the effects of the jet.

[0024] Figure 2 shows a low-pressure regulator 1B as a modified example of the low-pressure regulator 1A. Similar to the low-pressure regulator 1A, the low-pressure regulator 1B also includes a bypass fuel passage 10 formed by bypassing the on-off valve 8 from the fuel introduction passage 3 and communicating with the pressure regulating chamber 7, in order to cope with situations such as weak engine-side suction pressure during low-speed, low-opening operation from engine startup, and a bypass jet 13 attached to the terminal opening of the bypass fuel passage 10 and having a throttling structure 131 for injecting gaseous fuel toward the diaphragm 6.

[0025] In this example, the bypass jet 13, attached to the terminal opening of the bypass fuel passage 10, is a buffering means that causes the gaseous fuel jet to collide with the diaphragm 6 and change its direction so that it does not directly hit the diaphragm 6. The bypass jet 13 is characterized by having a shape that branches the linear flow path at the terminal end of the bypass fuel passage 10 into four radial (cross-shaped) discharge paths 132, 133, 134, and 135 perpendicular to its axial direction. This allows the gaseous fuel jet (black arrows shown in the diagram) to collide with the terminal end of the linear flow path and branch into multiple perpendicular and radial directions, guiding it in a direction different from the diaphragm 6, thus enabling an even better buffering function.

[0026] At this time, the jet of gaseous fuel, whose direction has been changed, may strike the surface of the diaphragm plate 61, which is attached on either side of the diaphragm 6. However, this does not pose a problem because it avoids the bulging portion 64, which is relatively susceptible to the effects of the jet.

[0027] Figure 3 shows a low-pressure regulator 1C as an application example of the low-pressure regulators 1A and 1B for gas fuel described above. This example is characterized by the provision of a shielding plate 14 that collides with the jet of gas fuel at a predetermined distance from the opening of a normal bypass jet 11 attached to the end of the bypass fuel passage 10, as a buffering means to change the direction of the jet of gas fuel so that it does not directly hit the diaphragm 6.

[0028] Even with this configuration, it is possible to deflect the jet of gaseous fuel (indicated by the black arrow in the diagram) ejected via the bypass fuel passage 10 by causing it to collide with the diaphragm 6 and changing its direction, thus preventing it from directly hitting the diaphragm 6. However, since the existing bypass jet 11 is used as is, and only the shielding plate 14 needs to be fixed inside the pressure regulating chamber 7, the present invention can be implemented at low cost and is easy to implement.

[0029] At this time, the gaseous fuel jet, whose direction has been changed, is guided along the shielding plate 14 in the lateral direction shown in Figure 3, so there is no risk of the gaseous fuel jet hitting the diaphragm 6.

[0030] Next, we will explain the results of actually fabricating the low-pressure regulators 1A and 1C for gas fuel shown in Figure 1 above, and testing their functions together with the conventional low-pressure regulator 1D, using the graph in Figure 4.

[0031] The graph in Figure 4 shows the characteristics (PQ characteristics) of the discharge flow rate [NL / min] and regulator outlet pressure [Pa] of a low-pressure regulator. In the case of a conventional low-pressure regulator 1D with only a bypass jet, the graph was zigzagging and unstable. In contrast, in the low-pressure regulator 1A, an embodiment of the present invention that uses a T-shaped bypass jet, and the low-pressure regulator 1C, an embodiment of the present invention that adds a shielding plate to the conventional bypass jet, both graphs showed a gentle curve and the PQ characteristics were stable. Therefore, it is considered that these have the function of stabilizing the regulator outlet pressure in all operating ranges of the engine.

[0032] As described above, the present invention makes it possible to stabilize the regulator outlet pressure in all operating ranges of the engine in a low-pressure regulator for gas fuel equipped with a bypass fuel passage that bypasses the on / off valve. [Explanation of symbols]

[0033] 1A, 1B, 1C, 1D Low-pressure regulator, 2 Body, 3 Fuel inlet passage, 4 Fuel outlet passage, 5 Atmospheric pressure chamber, 6 Diaphragm, 7 Pressure regulating chamber, 8 On / off valve, 9 Valve lever, 10 Bypass fuel passage, 11, 12, 13 Bypass jet, 14 Shielding plate, 61, 62 Diaphragm plate, 63 Rod, 64 Bulge section, 81 Valve body, 82 Valve seat, 91 Pressure regulating spring, 92 Tip, 93 Pin, 111, 121, 131 Throttle structure, 122, 123, 132, 133, 134, 135 Discharge passage

Claims

1. A body having a fuel inlet passage and a fuel outlet passage, A back pressure chamber formed within the body and communicating with the atmosphere, A pressure regulating chamber formed within the body and communicating with the fuel inlet passage and the fuel outlet passage, A diaphragm that separates the back pressure chamber and the pressure regulating chamber, A shut-off valve is provided between the fuel introduction passage and the pressure regulating chamber, A valve lever that acts as the on / off valve, oscillating due to the reciprocating displacement of the diaphragm while being biased by a pressure regulating spring, The system includes a bypass fuel passage that bypasses the on-off valve from the fuel introduction passage and communicates with the pressure regulating chamber, and which injects gaseous fuel from the throttling structure at the end towards the diaphragm, In a low-pressure regulator for gaseous fuel that reduces and adjusts the gaseous fuel introduced into the pressure regulating chamber from the fuel introduction passage to a predetermined pressure and sends it out from the fuel delivery passage, A low-pressure regulator for gas fuel is characterized in that a buffering means is provided at the terminal opening of the bypass fuel passage to cause the gas fuel jet to collide with and change its direction so that it does not directly hit the diaphragm.

2. The low-pressure regulator for gas fuel according to claim 1, characterized in that the buffering means is T-shaped, which branches the flow path at the end of the straight bypass fuel passage into two paths perpendicular to its axial direction.

3. The low-pressure regulator for gas fuel according to claim 1, characterized in that the buffering means is shaped to branch the flow path at the end of a straight bypass fuel passage into three or more radial lines perpendicular to its axial direction.

4. The low-pressure regulator for gas fuel according to claim 1, characterized in that the buffering means is a shielding plate that causes the jet to collide at a predetermined distance from the opening of the bypass fuel passage.

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