JPH09119363A - High-pressure pump and fuel supplying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain cavitation to be generated on the suction side in the high rotation of a high-pressure pump by providing an orifice for throttling the flow rate of high-pressure fuel on the discharging side of the high-pressure pump, and connecting a recirculating means for returning fuel to the suction side with the specified pressure or more upstream from the orifice and on the suction side of the high-pressure pump. SOLUTION: In starting of an engine, a fuel pressure selector valve 66 is switched into the state as shown in the figure, fuel in a fuel tank 1 is boosted to the specified pressure by a low-pressure pump 2 and recirculated from a low-pressure pipe 4 to the fuel tank 1 through a side passage valve 63, a high- pressure pipe 7, a fuel distributing pipe 9, a high-pressure pipe 10, the fuel pressure switching valve 66 and an orifice 67. Therefore, steam filled in respective fuel pipes are returned to the fuel tank 1. Differential pressure upstream and downstream from the orifice 69 is increased in the normal operation, pressure upstream from the orifice 69 is increased, and therefore, fuel is returned to the suction side of a high-pressure pump 61 through a relief valve 68, and the insufficient of discharge flow rate of a low-pressure pump 2 is supplemented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure pump device for increasing the pressure of fuel and a fuel supply device capable of directly injecting fuel into a cylinder of an internal combustion engine using the high-pressure pump device. .

[0002]

2. Description of the Related Art Conventionally, there has been a fuel supply device for boosting the fuel from a fuel tank to a predetermined pressure by a low pressure pump, further boosting the pressure by a high pressure pump, and pumping the fuel into a fuel injection valve through a fuel distribution pipe or the like. Proposed (for example, Japanese Patent Laid-Open No. 4-191)
461). In such an apparatus, a high-pressure regulator that adjusts the flow rate by opening and closing a valve is further provided on the downstream side of the fuel distribution pipe, and when the fuel pressure in the fuel distribution pipe exceeds a predetermined high pressure, excess fuel is removed by the high-pressure regulator. It is returned to the inside of the fuel tank to maintain a constant high pressure.

[0003]

By the way, in the fuel supply device as described above, the high-pressure pump is connected to the camshaft of the engine and driven by the camshaft, so that the discharge flow rate changes in proportion to the engine speed. . On the other hand, the low-pressure pump is a so-called Wesco pump that is driven by a DC motor that operates on a battery voltage, and discharges a substantially constant flow rate regardless of the engine speed.

Therefore, the discharge flow rate of the low-pressure pump at the time of high rotation of the high-pressure pump becomes insufficient, that is, the flow rate on the suction side of the high-pressure pump (the discharge flow rate of the low-pressure pump) becomes lower than the flow rate on the discharge side of the high-pressure pump. When the pressure on the suction side drops below the vapor pressure of the fuel, so-called cavitation occurs, which causes bubbles on the suction side of the high-pressure pump.When the bubbles flow to the high-pressure side, the bubbles collapse and localize. If ultra-high pressure is generated, causing damage to pipes and other materials, pressure fluctuations, noise, etc., and increasing the discharge flow rate of the low pressure pump that corresponds to the suction side flow rate of the high pressure pump, the power consumption of the low pressure pump increases. There is a problem that the loss becomes large.

The present invention has been made to solve the above problems, and suppresses cavitation generated on the suction side when the high-pressure pump rotates at high speed to prevent damage to materials such as piping and pressure fluctuations or noise. An object of the present invention is to provide a highly reliable high-pressure pump device and a fuel supply device that can be prevented in advance.

[0006]

A high-pressure pump device according to the present invention is a high-pressure pump that sucks and pressurizes fuel from the outside, and a high-pressure fuel that is provided on the discharge side of the high-pressure pump and is discharged from the high-pressure pump. Is provided with an orifice for narrowing the flow rate and a recirculation means connected to the upstream side of the orifice and the suction side of the high pressure pump for returning the fuel from the discharge side of the high pressure pump to the suction side at a predetermined pressure or higher.

The high-pressure pump device according to the present invention is
A check valve provided between the high-pressure pump and the orifice is provided, and the upstream side of the reflux means is connected to the downstream side of the check valve.

The high-pressure pump device according to the present invention is
A check valve is provided on the downstream side of the orifice, and the upstream side of the reflux means is connected to the upstream side of the orifice.

The fuel supply device according to the present invention is provided with a low pressure pump for discharging fuel from the fuel tank, a high pressure pump for sucking and pressurizing fuel from the low pressure pump, and a discharge side of the high pressure pump. An orifice for reducing the flow rate of the high-pressure fuel discharged from the high-pressure pump, and a recirculation means connected to the upstream side of the orifice and the suction side of the high-pressure pump to return the fuel from the discharge side of the high-pressure pump to the suction side at a predetermined pressure or higher. A fuel injection valve for injecting high-pressure fuel from the high-pressure pump into the cylinder, which is provided in a fuel distribution pipe connected to the high-pressure pump, and connected to the high-pressure pump via the fuel distribution pipe to be discharged from the high-pressure pump. And a high pressure adjusting means for adjusting the pressure of the high pressure fuel.

Further, the fuel supply device according to the present invention comprises a check valve provided between the high pressure pump and the orifice,
The upstream side of the reflux means is connected to the downstream side of the check valve.

Further, the fuel supply device according to the present invention comprises a check valve provided between the orifice and the fuel distribution pipe,
The upstream side of the reflux means is connected to the upstream side of the orifice.

The fuel supply device according to the present invention is provided between the fuel distribution pipe and the downstream side of the high pressure adjusting means,
A fuel pressure switching valve that opens and closes the high pressure passage according to the operation mode is provided, and this fuel pressure switching valve is integrally loaded in the pump housing together with the high pressure pump and the high pressure adjusting means.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention. In the figure, an electric low-pressure pump 2 is provided in a fuel tank 1 containing fuel. The low-pressure pump 2 may be, for example, a so-called Wesco pump driven by a DC motor that operates on a battery voltage, and discharges a substantially constant flow rate regardless of the engine speed. The low pressure pump 2 is connected to the suction side of the high pressure pump 61 in the high pressure pump device 6 via the check valve 3 and the low pressure pipe 4. The high-pressure pump 61 is connected to a camshaft of an engine (not shown) and is driven by the camshaft so that the discharge flow rate changes in proportion to the engine speed.

Further, a low pressure regulator 5 for adjusting the flow rate by opening and closing a valve is provided between the low pressure pipe 4 and the fuel tank 1. The discharge side of the high-pressure pump 61 is connected to the upstream side of the fuel distribution pipe 8 via the check valve 62, the orifice 69, and the high-pressure pipe 7 as a high-pressure passage. High-pressure pump device 6
Inside, the bypass valve 63 is connected between the suction side of the high-pressure pump 61 and the downstream side of the orifice 69.

Further, a high pressure regulator 64 as a high pressure adjusting means for adjusting the flow rate by opening and closing a valve is provided inside the high pressure pump device 6, and the upstream side of this high pressure regulator 64 is provided with a high pressure pipe 10 as a high pressure passage. Is connected to the downstream side of the fuel distribution pipe 9, and the downstream side of the high pressure regulator 64 communicates with the inside of the fuel tank 1 via a return pipe 65. A fuel injection valve 9 is provided in the fuel distribution pipe 8. Further, a fuel pressure switching valve 66 is provided inside the high-pressure pump device 6, the upstream side thereof is connected to the upstream side of the high-pressure regulator 64, and the downstream side thereof is downstream of the high-pressure regulator 64 via the orifice 67, that is, the return pipe. Connected to 65.

This fuel pressure switching valve 66 has its solenoid 6
By controlling the voltage applied to 6a, it is turned on when the engine is started, that is, the valve is opened (the opposite of the illustrated state), and is turned off when the engine is operating normally, that is, the valve is closed (the illustrated state). is there. Further, a relief valve 68 is provided between the downstream side of the check valve 62 and the suction side of the high pressure pump 61, the upstream side of the relief valve 68 is connected to the downstream side of the check valve 62, and the downstream side of the relief valve 68 is connected. It is connected to the suction side of the high-pressure pump 61.

The relief valve 68 normally uses a spring or the like to increase the pressure retained in the high-pressure piping system to, for example, 50.
When pressure is set to 80 atm, which is slightly higher than this, the valve is pressed and closed. If an abnormal rise in pressure occurs due to blockage of the high-pressure piping system, the valve is opened against the pressure of the spring and the pressure is increased. Although it is released to prevent destruction of the high pressure piping system and the like, here, in addition to this function, the relief valve 6 is provided from the upstream side of the orifice 69, that is, the downstream side of the check valve 62.
Fuel is returned to the suction side of the high-pressure pump 61 via 8 and also functions as a recirculation means so as to replenish the shortage of the discharge flow rate of the low-pressure pump 2 when the high-pressure pump 61 rotates at high speed. Therefore, the relief pressure of the relief valve 68 is set to a pressure at which the discharge flow rate of the high pressure pump 61 becomes larger than the discharge flow rate of the low pressure pump 2. The high-pressure pump 61, the check valve 62, the bypass valve 63, the high-pressure regulator 64, the fuel pressure switching valve 66, the orifices 67 and 69, and the relief valve 68 in the high-pressure pump device 6 are integrated in a pump housing (not shown). Be loaded into.

Next, the operation will be described. When the engine is started, the fuel pressure switching valve 66 is switched from the state shown in the figure by the voltage application to its solenoid 66a to be in the ON state, and the fuel in the fuel tank 1 is slightly lower than a predetermined pressure in the low pressure pump 2, for example, 3 atm. The pressure is increased to a high pressure, passes through the bypass valve 63 via the low pressure pipe 4, and further reaches the high pressure pipe 7, the fuel distribution pipe 9, the high pressure pipe 10, the fuel pressure switching valve 66, and the orifice 67. At this time, since the flow rate of the fuel is throttled by the orifice 67, the low pressure regulator 5 adjusts the flow rate by opening and closing the valve to return the excess fuel to the fuel tank 1 to adjust the pressure. The path to 67 is maintained at a predetermined pressure, that is, 3 atm. Then, after the orifice 67, the fuel flows to the fuel tank 1 through the return pipe 65 at the same atmospheric pressure as the normal atmospheric pressure. As a result, the vapor filled in each fuel pipe is returned to the fuel tank 1.

On the other hand, during normal engine operation, the fuel pressure switching valve 66 is turned off by switching the voltage applied to its solenoid 66a to the state shown in the figure, and the fuel in the fuel tank 1 has a low pressure as described above. The pressure is increased by the pump 2, regulated to a predetermined pressure of 3 atm by the low pressure regulator 5, and supplied to the suction side of the high pressure pump 61 via the low pressure pipe 4.

Then, the high-pressure pump 61 boosts the sucked fuel to a predetermined pressure, for example, 50 atmospheric pressure, and discharges it to the discharge side. The fuel discharged to the discharge side receives the check valve 62.
Further, it is supplied to the fuel injection valve 9 through the orifice 69, the high pressure pipe 7 and the fuel distribution pipe 8. The remaining difference in the flow rate consumed by the fuel injection valve 9 is calculated from the fuel distribution pipe 8 to the high pressure pipe 10 and the high pressure regulator 64.
And returns to the fuel tank 1 through the return pipe 65.

When the engine speed increases during such normal engine operation, the high-pressure pump 61 also increases in speed, and the discharge flow rate increases, resulting in a pressure difference between the upstream side and the downstream side of the orifice 69. Since the pressure is increased and the downstream side is regulated by the high pressure regulator 64, the pressure on the upstream side of the orifice 69 is increased. The relief pressure of the relief valve 68 is set to the pressure when the discharge flow rate of the high pressure pump 61 becomes larger than the discharge flow rate of the low pressure pump 2 as described above, so that the relief valve 68 is set from the upstream side of the orifice 69. Through high pressure pump 61
Fuel is returned to the intake side of the high pressure pump 6
The shortage of the discharge flow rate of the low-pressure pump 2 at the time of high rotation of 1 is replenished. Thus, the flow rate on the suction side of the high-pressure pump 61 does not decrease as compared with the discharge flow rate, so that the pressure on the suction side of the high-pressure pump 61 is secured and the occurrence of cavitation is prevented. When an abnormal increase in pressure occurs due to the blockage of the high-pressure piping system such as the high-pressure piping 7 and 10, the relief valve 68 is opened to release the pressure, and the high-pressure piping system is prevented from being destroyed.

As described above, in the present embodiment, the orifice is provided on the downstream side of the check valve on the discharge side of the high pressure pump,
Since the fuel is returned from the upstream side of the orifice to the suction side of the high pressure pump through the relief valve, the cavitation on the suction side at the time of high rotation of the high pressure pump is suppressed to prevent damage to pipes and other materials, pressure fluctuations, noise, etc. Can be prevented and the reliability of the device can be improved. Further, since each component of the high-pressure pump device is integrally loaded inside the pump housing, it can be easily handled and improved in workability even when mounted on a vehicle or the like, and can be standardized as a product. It is also advantageous from the aspect.

Embodiment 2 FIG. 2 is a configuration diagram showing a second embodiment of the present invention. In the figure, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. The high-pressure pump device 6A in the present embodiment is provided with a check valve 62 on the downstream side of the orifice 69 and has a relief valve 68.
Is connected to the discharge side of the high-pressure pump 61, that is, the upstream side of the orifice 69. Other configurations are the same as those in FIG.

Next, the operation will be described. Since the operation at the time of starting the engine is the same as that in the case of FIG. 1, its explanation is omitted. During normal engine operation, the voltage applied to the solenoid 66a of the fuel pressure switching valve 66 is cut off, and the fuel pressure switching valve 66 is switched to the state shown in the figure to turn off.
As described above, the fuel in the fuel tank 1 is boosted by the low pressure pump 2, regulated to a predetermined pressure of 3 atm by the low pressure regulator 5, and supplied to the suction side of the high pressure pump 61 via the low pressure pipe 4.

Then, the high-pressure pump 61 boosts the sucked fuel to a predetermined pressure, for example, 50 atmospheric pressure, and discharges it to the discharge side. The fuel discharged to the discharge side passes through the orifice 69 and the check valve 62, and is further supplied to the fuel injection valve 9 through the high pressure pipe 7 and the fuel distribution pipe 8. The remaining difference in the flow rate consumed by the fuel injection valve 9 is calculated from the fuel distribution pipe 8 to the high pressure pipe 10 and the high pressure regulator 64.
And returns to the fuel tank 1 through the return pipe 65.

During such normal engine operation, as the engine speed increases, the high-pressure pump 61 also increases in speed, and the discharge flow rate increases, resulting in a pressure difference between the upstream side and the downstream side of the orifice 69. Since the pressure is increased and the downstream side is regulated by the high pressure regulator 64, the pressure on the upstream side of the orifice 69 is increased. Also in this case, since the relief pressure of the relief valve 68 is set to the pressure when the discharge flow rate of the high pressure pump 61 becomes larger than the discharge flow rate of the low pressure pump 2 as described above, the relief pressure from the upstream side of the orifice 69. Fuel is returned to the suction side of the high-pressure pump 61 via the relief valve 68, and the flow rate replenishes the shortage of the discharge flow rate of the low-pressure pump 2 during high rotation of the high-pressure pump 61. Thus, the high pressure pump 61
Since the flow rate on the suction side does not decrease as compared with the discharge flow rate, the pressure on the suction side of the high-pressure pump 61 is secured and cavitation is prevented. Also in this case,
When an abnormal increase in pressure occurs due to the blockage of the high-pressure piping system such as the high-pressure piping 7 and 10, the relief valve 68 is opened to release the pressure, and the high-pressure piping system is prevented from being destroyed.

As described above, also in this embodiment, the orifice is provided on the upstream side of the check valve on the discharge side of the high pressure pump,
Since the fuel is returned from the upstream side of the orifice to the suction side of the high pressure pump through the relief valve, the cavitation on the suction side at the time of high rotation of the high pressure pump is suppressed to prevent damage to pipes and other materials, pressure fluctuations, noise, etc. Can be prevented and the reliability of the device can be improved. Further, since each component of the high-pressure pump device is integrally loaded inside the pump housing, it can be easily handled and improved in workability even when mounted on a vehicle or the like, and can be standardized as a product. It is also advantageous from the aspect.

Further, in the case of the above described first embodiment,
When the engine is stopped and the operation of the high-pressure pump 61 is stopped, the fuel on the high-pressure pipes 7 and 10 side leaks through the check valve 62, the bypass valve 63, the high-pressure regulator 64, the fuel pressure switching valve 66 and the relief valve 68. However, in the present embodiment, by connecting the upstream side of the relief valve 68 to the upstream side of the check valve 62,
Since only the check valve 62, the bypass valve 63, the high pressure regulator 64 and the fuel pressure switching valve 66 are taken into consideration and the relief valve 68 can be omitted, at least the processing accuracy of the relief valve 68 can be reduced, and that much. The cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

1 Fuel Tank, 2 Low Pressure Pump, 5 Low Pressure Regulator, 6,6A High Pressure Pump Device, 61 High Pressure Pump, 6
2 Check valves, 64 high pressure regulator, 66 fuel pressure switching valve, 68 relief valve, 69 orifice, 7,1
0 high pressure pipe, 8 fuel distribution pipe, 9 fuel injection valve.

Claims (7)

[Claims] 1. A high-pressure pump for sucking and pressurizing fuel from the outside, an orifice provided on the discharge side of the high-pressure pump for reducing the flow rate of the high-pressure fuel discharged from the high-pressure pump, and an upstream side of the orifice. And a recirculation unit connected to the suction side of the high-pressure pump and returning fuel from the discharge side of the high-pressure pump to the suction side at a predetermined pressure or higher. 2. A check valve provided between the high pressure pump and the orifice, wherein the check valve is connected to the upstream side of the reflux means downstream of the check valve. High-pressure pump device. 3. The high-pressure pump device according to claim 1, wherein a check valve is provided on the downstream side of the orifice, and the upstream side of the reflux means is connected to the upstream side of the orifice. 4. A low-pressure pump for discharging fuel from the fuel tank, a high-pressure pump for sucking and pressurizing fuel from the low-pressure pump, and a discharge side of the high-pressure pump, which discharges from the high-pressure pump. An orifice for reducing the flow rate of the high-pressure fuel, a recirculation means connected to the upstream side of the orifice and the suction side of the high-pressure pump for returning the fuel from the discharge side of the high-pressure pump to the suction side at a predetermined pressure or higher, A fuel injection valve, which is provided in a fuel distribution pipe connected to the pump and injects high-pressure fuel from the high-pressure pump into the cylinder, is connected to the high-pressure pump via the fuel distribution pipe and is discharged from the high-pressure pump. And a high-pressure adjusting means for adjusting the pressure of the high-pressure fuel. 5. A check valve provided between the high-pressure pump and the orifice, wherein the check valve is connected downstream of the check valve and upstream of the return means. Fuel supply device. 6. The fuel according to claim 4, further comprising a check valve provided between the orifice and the fuel distribution pipe, wherein an upstream side of the recirculation means is connected to an upstream side of the orifice. Supply device. 7. A fuel pressure switching valve, which is provided between the fuel distribution pipe and a downstream side of the high pressure adjusting means, opens and closes a high pressure passage in accordance with an operation mode, and the fuel pressure switching valve includes the high pressure pump and the high pressure. The fuel supply device according to any one of claims 4 to 6, wherein the fuel supply device is integrally loaded in the pump housing together with the adjusting means.