JPH0415372B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbocharged engine equipped with a plurality of turbochargers having different operating ranges, and particularly to a lubrication structure for the turbocharger.

BACKGROUND ART The technical concept of improving the output performance of an engine by increasing the pressure of intake air using a turbocharger to improve charging efficiency has been well known.

By the way, the turbocharger attached to the engine is
During supercharging, the engine is driven at extremely high speeds of 10 to 20 x 10 ⁴ rpm, so lubrication of the rotating shaft that connects the turbine and blower is extremely important, and the engine is usually supplied by an oil pump. A portion of the lubricating oil is supplied to the bearing portion of the rotating shaft to lubricate it (see Japanese Utility Model Publication No. 132032/1983).

On the other hand, there is now a demand for improving output performance through supercharging not only when the engine is running at high speeds but also when operating at low speeds, and the above requirements can be met with a single turbo supercharger. What to do is
Since it is extremely difficult in practice to improve the efficiency of a turbocharger, a technical concept has been proposed that attempts to meet this requirement by installing multiple turbochargers in parallel. (Refer to Publication No. 159626/1982 and Japanese Patent Application Laid-open No. 118117/1983).

That is, in the above-mentioned Japanese Utility Model Application Publication No. 56-159626, a low-speed turbo supercharger that has good efficiency in the low-speed range of the engine and a high-speed turbo supercharger that has good efficiency in the high-speed range of the engine are installed side by side. However, according to the operating condition of the engine, a turbo supercharger for low speed and high speed can be switched and used.
-Publication No. 118117 basically describes the equivalent primary and secondary
A secondary turbo supercharger is installed in parallel, so that only the primary turbo supercharger is used during low-speed operation of an engine with a small intake air amount, and both the primary and secondary turbo superchargers are used during high-speed operation of an engine with an increased intake air amount. A method using a feeder has been proposed.

In an engine with such a plurality of turbo superchargers installed in parallel, for example, in the case of the former, the high-speed turbo supercharger is stopped when the engine speed is low, and the low-speed turbo supercharger is stopped when the engine is running at high speed. Regarding the latter, some of the turbochargers are stopped in a specific operating range of the engine, just as the secondary turbocharger is stopped when the engine is at low speed.

As mentioned above, when some of the turbochargers are stopped in a specific operating range of the engine, that is, when the turbine is not driven by exhaust gas, the internal pressure of the turbine and blower naturally decreases. The pressure drops to atmospheric pressure, which is significantly lower than the pressure of the lubricating oil supplied to the bearings of the rotating shaft by the oil pump. As a result, the pressure balance between the inside and outside of the rotating shaft bearing, which had been maintained well when the turbocharger was running, was disrupted, and some of the lubricating oil leaked from the bearing to the turbine and blower sides, wasting lubricating oil. In addition, it causes problems such as contamination of turbines and blowers.

Oil leakage from the bearing lubricating part of the turbocharger is typically a problem for turbochargers that are stopped in a specific operating range as described above, but essentially oil leakage from the bearing lubricating part of the rotating shaft is a problem. This occurs when the pressure difference between the hydraulic pressure of the engine and the internal pressure of the turbine or blower increases to the extent that it exceeds the sealing capacity of the bearing seal. Therefore, when considering individual turbochargers, when the rotational speed of the turbocharger decreases and it is not actually supercharging, the internal pressure of the turbine and blower also decreases, causing the oil leak mentioned above. There is a risk.

The present invention has been made in view of this problem, and includes monitoring the rotation of each turbocharger,
When the rotational speed of the turbocharger falls below a preset rotational speed corresponding to the operating range of the turbocharger, the amount of lubricating oil supplied to the rotating shaft of the turbocharger in response to this decreases. The basic purpose is to reduce the pressure of the lubricating oil at the rotating shaft bearing, maintain a pressure balance with the internal pressure of the turbine and the blower, and prevent leakage of the lubricating oil.

Hereinafter, the present invention will be described in more detail based on illustrated embodiments.

<First Embodiment> In FIG. 1, 1 is an engine, 2 is an intake passage of the engine 1, 3 is an exhaust passage of the engine 1, and 4 is the highest point of the intake passage 2 for measuring the momentary intake air amount of the engine 1. The air flow sensors 5 and 6 are arranged in the upstream part, and the first and second branch intake passages are formed in parallel between the downstream side of the air flow sensor 4 of the intake passage 2 and the upstream side of the throttle valve 7. 1,
Blower 8a, 9a interposed in the middle of the second branch intake passages 5, 6 is interposed in the first and second branch exhaust passages 10, 11 formed by bifurcating the exhaust passage 3 in the middle, respectively. The turbines 8b and 9b have rotating shafts 8c,
This is a low-speed and high-speed turbo supercharger connected by 9c.

The rotating shafts 8c, 9c each have a pair of bearings 8d, 8d, 9 having a structure known per se.
d and 9d, and is lubricated by lubricating oil supplied to oil jackets 8e and 9e.

The low speed turbo supercharger 8 is a turbo supercharger that has good efficiency in the low speed range of the engine 1, and when the engine 1 is operating at low speed, the first
With the exhaust switching valve 12 provided at the branch part 3a between the branch exhaust passage 10 and the second branch exhaust passage 11 closing the second branch exhaust passage 11, the first branch exhaust passage 10
When the turbine 8b is driven by the exhaust gas flowing down, the pressure of the intake air is increased by the blower 8a which is linked to the rotation of the turbine 8b, thereby supercharging the engine 1 at low speed.

On the other hand, the high-speed turbo supercharger 9 is a turbo supercharger that has good efficiency in the high-speed range of the engine 1, and when the engine 1 is operating at high speed, the exhaust switching valve 12 and the first and second branch The intake switching valve 13 provided at the merging portion 2a of the intake passages 5 and 6,
As shown by the dotted line in the figure, when the first branch exhaust passage 10 and the first branch intake passage 5 are closed while the second branch exhaust passage 11 and the second branch intake passage 6 are opened, the flow flows down the second branch exhaust passage 11. The turbine 9b is driven by the exhaust gas, and the blower 9a that is linked to the turbine 9b boosts the pressure of the intake air, and the second branch intake passage 6
The engine 1 is supercharged via the. In other words, when the engine 1 is operating at high speed, the high speed turbocharger 9 performs supercharging instead of the low speed turbocharger 8.

Reference numeral 14 uses the output signal of the air flow sensor 4 as a basic input signal to determine the opening time of the fuel injection valve 15 installed downstream of the throttle valve 7 in the intake passage 2 and the exhaust and intake switching valves 12 and 13. Electromagnetically actuated actuators 16 and 1 provided respectively.
7, and a second control circuit 14B that controls the lubricating oil supplied to the rotating shafts 8c and 9c of the low-speed and high-speed turbo superchargers 8 and 9, as described later. This is a control circuit equipped with As shown in FIG. 2, the first control circuit 14A operates to open the fuel injection valve 15 during a valve opening time determined by the injection pulse generation circuit 18 according to the intake air amount detected by the air flow sensor 4. The comparison circuit 19 compares the intake air amount with a set value, and when the intake air amount does not reach the set value and the engine 1 is running at low speed, each of the actuators 16 and 17 is held inactive, and when the intake air amount reaches the set value or more, Each actuator 16, 17 is actuated via an amplifier circuit 20,
Each switching valve 12, 13 is switched from the solid line position to the dotted line position in FIG.

Again, in FIG. 1, 21 is an oil pan which is a circulating supply source of lubricating oil, 22 is an oil pump driven by the output shaft (not shown) of the engine 1,
23, lubricating oil discharged from the oil pump 22 is connected to the rotating shafts 8 of the low-speed and high-speed turbo superchargers 8 and 9.
The lubricating oil supply path 23 is for supplying the lubricating oil to the low-speed turbo supercharger 8.
The low-speed lubricating oil supply path 24 leads to the oil jacket 8e of the high-speed turbo supercharger 9, and the high-speed lubricating oil supply path 25 connects to the oil jacket 9e of the high-speed turbo supercharger 9. These low-speed and high-speed lubricating oil supply paths 24 and 25 are provided with low-speed and high-speed lubricating oil supply paths 24 and 25, respectively.
High-speed solenoid valves 26 and 27 are provided.

The above low speed and high speed solenoid valves 26 and 27
is controlled individually according to the driving state of the low speed and high speed turbochargers 8 and 9, so each blower 8a,
9a is for low speed, which boosts the rotation.
High-speed rotation sensors 28 and 29 are installed, respectively.

These low speed and high speed rotation sensors 28, 29
As shown in FIG.
is input to the second control circuit 14B. This second control circuit 14B includes a low speed rotation sensor 28, a high speed rotation sensor 28,
29, first and second comparison circuits 30 and 31 compare the respective rotational speeds of the low-speed and high-speed turbo superchargers 8 and 9 with preset values;
connected to each output side of the second comparison circuits 30 and 31;
When the rotation speed increases beyond the set value and the outputs of the first and second comparison circuits 30 and 31 rise, this is amplified and the first solenoid valve for low speed and high speed, 26 and 27 is opened. , second amplifier circuits 32 and 33. The above setting value is the rotation speed at which the turbochargers 8 and 9 can be considered not to substantially participate in supercharging, in other words, the bearing portions 8d of the low-speed and high-speed turbochargers 8 and 9, The rotation speed is set at a speed at which oil leakage from 8d, 9d, 9d to the turbines 8b, 9b and blowers 8a, 9a may occur. In the second control circuit 14B, the low-speed and high-speed solenoid valves 2
6 and 27 are controlled individually,
The above set values may be set individually for the first and second comparison circuits 30 and 31.

In addition, the first and second comparison circuits 30 and 31 and the low speed
The relationship with the high-speed solenoid valves 26 and 27 depends on whether the low-speed and high-speed solenoid valves 26 and 27 are normally closed or normally open.
In short, the configuration may be such that the supply of lubricating oil can be cut off when the rotational speeds of the low-speed and high-speed turbochargers 8 and 9 fall below a set value.

Next, the operation of the first embodiment will be explained.

Before the intake air amount detected by the air flow sensor 4 reaches the set value, the comparator circuit 19 of the first control circuit 14A does not produce an output, and the exhaust and intake switching valves 12 and 13 are switched to the second branch. Exhaust passage 1
1, the second branch intake passage 6 is closed, and when the throttle valve 7 is fully opened, the entire amount of exhaust gas that increases commensurately flows down the first branch exhaust passage 10 and reaches the low-speed turbo supercharger 8. The turbine 8b is driven at high speed. Therefore, when the low-speed turbo supercharger 8 starts supercharging and at the same time its rotation speed exceeds the set value, the output of the first comparison circuit 30 of the second control circuit 14B rises, and the first amplifier circuit 32 The low speed solenoid valve 26 is opened via the solenoid valve 26. Therefore, the lubricating oil is supplied from the low-speed lubricating oil supply path 24 to the oil jacket 8e of the low-speed turbocharger 8, and the rotating shaft 8c is well lubricated without oil leakage.

At this stage, the high-speed turbo supercharger 9 is not being driven, and the rotation sensor 2 of the high-speed turbo supercharger 9
Since the output of the high-speed turbo supercharger 9 is substantially zero, the high-speed solenoid valve 27 remains closed, and high-pressure lubricating oil is not supplied to the oil jacket 9e. No leakage will occur.

On the other hand, during high-speed operation of the engine 1 in which the intake air amount increases above the set value, the output of the comparison circuit 19 of the first control circuit 14A rises, the actuators 16 and 17 are operated via the amplifier circuit 20, and the exhaust gas is A switching valve 12 closes the first branch exhaust passage 10 and closes the second branch exhaust passage 10.
While opening the branch exhaust passage 11, the intake switching valve 1
3 closes the first branch intake passage 5 and opens the second branch intake passage 6, and the low-speed turbo supercharger 8 is stopped.
Instead, driving of the high-speed turbocharger 9 is started.

The exhaust switching valve 12 is switched and the throttle valve 7
When the is fully opened, the entire amount of exhaust gas flows down the second branch exhaust passage 11, and the turbine 9b interposed in this passage 11 is driven at high speed, thereby increasing the rotation of the high-speed turbo supercharger 9. The output of the sensor 29 rises and exceeds the set value, and the second comparison circuit 31 operates.
The high speed solenoid valve 27, which had been closed until then, is opened via the second amplification circuit 33. on the other hand,
The turbine 8b of the low-speed turbocharger 8 is rapidly decelerated by switching the exhaust gas, the output of the rotation sensor 28 falls, and the low-speed solenoid valve 26
is opened when the rotational speed drops below a set value. As a result, the supply of lubricating oil to the rotating shaft 8c of the low-speed turbocharger 8 is stopped, and leakage of lubricating oil to the turbine 8b and blower 8a is prevented, while the oil of the high-speed turbocharger 9 is stopped. Lubricating oil is supplied to the jacket 9e from the high-speed lubricating oil supply path 25, and the rotating shaft 9c is well lubricated.

In addition, in FIG. 1, 34 connects the upstream exhaust passage 3u between the branch part 3a of the first and second branch exhaust passages 10, 11 and the engine 1 to the low-speed and high-speed turbo superchargers 8, 9. An exhaust bypass passage that bypasses both the turbines 8b and 9b and communicates with the downstream exhaust passage 3d; 35 is a supercharging pressure control valve that opens and closes a valve seat 36 provided in the middle of the exhaust bypass passage 34; 37;
38 is a control diaphragm device for the supercharging pressure control valve 35 in which the supercharging pressure control valve 35 is supported by a diaphragm 37b via a rod 37a, and 38 is a positive pressure chamber 37c of the control diaphragm device 37, with first and second branches. This is a supercharging pressure introducing passage that introduces the supercharging pressure of the downstream side intake passage 2d downstream of the confluence portion 2a of the intake passages 5 and 6.
Another chamber 37d separated from the positive pressure chamber 37c by the diaphragm 37b of the control diaphragm device 37 is formed as an atmospheric chamber communicated with the atmosphere through the atmosphere opening hole 37e, and this atmospheric chamber 37d A coil spring 37f is compressed inside, and the set load of this coil spring 37f is
Set according to the maximum boost pressure, which is the control target.

This maximum boost pressure is basically set in consideration of the reliability of the engine 1.

With the above configuration, supercharging is generated in the downstream intake passage 2d by the low-speed turbo supercharger 8 during low-speed operation of the engine 1, and by the high-speed turbo supercharger 9 during high-speed operation. When the pressure reaches the maximum boost pressure, the boost pressure introduced into the positive pressure chamber 37c of the control diaphragm device 37 exceeds the set load of the coil spring 37f, the diaphragm 37b is displaced, and the boost pressure is controlled. As a result of the valve 35 being opened, the exhaust bypass passage 34 is opened. Therefore, part of the exhaust gas is transferred to the exhaust bypass passage 3.
4 to the downstream exhaust passage 3d,
The boost pressure in the downstream intake passage 2d is lowered below the maximum boost pressure. Therefore, the supercharging air supplied to the engine 1 is maintained below the maximum supercharging pressure, and the engine 1 is operated well without deteriorating its reliability, and exhibits good output performance due to supercharging. .

<Second Embodiment> In the second embodiment shown in FIG. 3, basically equivalent primary and secondary turbo superchargers 39 and 40 are installed in parallel, and when the engine 1 is operated at low speed with a small intake air amount, , the primary turbo supercharger 39 is used, and when the engine 1 is operated at high speed when the intake air amount increases, supercharging is performed by sharing the increased intake air amount with both the primary and secondary turbo superchargers 39 and 40. The present invention is applied to a type of turbocharged engine.

For this reason, the blower 40 of the secondary turbocharger 40
A check valve 41 is provided downstream of the blower in the second branch intake passage 6 via a, while a check valve 41 is provided upstream of the turbine in the second branch exhaust passage 11 in which the turbine 40b of the secondary turbocharger 40 is provided. The exhaust control valve 42 is provided to control the operation of the secondary turbocharger 40.

That is, the first control circuit 14A of the control circuit 14 is
As shown in FIG. 4, the intake air amount detection signal of the air flow sensor 4 is compared with a set value, and when the intake air amount exceeds the set value, a comparison circuit 19 is sent to the exhaust control valve 42 via an amplifier circuit 20. The actuator 43 provided at the exhaust control valve 42 is actuated to open the exhaust control valve 42, thereby opening the second branch exhaust passage 11.

When the second branch exhaust passage 11 is opened, the exhaust gas flowing down this passage 11 causes the turbine 40 to
b is driven, and the secondary turbo supercharger 40 starts supercharging. When the drive of the secondary turbo supercharger 40 is started, the check valve 41 is opened, and the air flows from the downstream side intake passage 2d downstream of the merging section 2a where the first and second branch intake passages 5 and 6 join. The supercharged air supplied by the primary turbocharger 39 and the secondary turbocharger 40
Both supercharging air supplied by the engine 1 are supplied to the engine 1.

In this second embodiment as well, the lubricating oil control system is substantially the same as that in the first embodiment.

That is, when the engine 1 is operating at low speed, when the speed of the primary turbocharger 39 is increased to the extent that it starts supercharging, the rotation sensor 44 installed for the primary turbocharger 39 works. , the second shown in FIG.
The first comparison circuit 30 of the control circuit 14B operates to open the primary solenoid valve 46 interposed in the primary lubricating oil supply path 24' via the first amplifier circuit 32.
Necessary lubrication is performed by supplying lubricating oil to the rotating shaft 39c supported by bearings 39d, 39d of the next turbo supercharger 39 via an oil jacket 39e.

On the other hand, during high-speed operation of the engine 1 in which the secondary turbo supercharger 40 performs supercharging in addition to the primary turbo supercharger 39, the rotation sensor 45 installed for the secondary turbo supercharger 40 detects the rotation of the blower 40a. High rotation is detected, the second comparison circuit 31 is operated, the secondary solenoid valve 47 is opened via the second amplifier circuit 33, and the secondary turbo supercharger is connected to the secondary lubricating oil supply path 25'. The lubricating oil is also supplied to the oil jacket 40e of the secondary turbo supercharger 40, and the bearings 40d,
This effectively lubricates the rotating shaft 40c supported by the shaft 40d.

Regarding the above-described second embodiment, parts that are not different from the first embodiment are given the same or corresponding numbers, and redundant explanation will be omitted.

In addition, in the first and second embodiments, the solenoid valves 26, 27, 46, 4 that control the supply of lubricating oil are
7 is an on/off type on-off valve, but it goes without saying that a flow control valve that reduces the amount of lubricating oil to prevent oil leakage when the turbocharger is not in use may be used. .

As is clear from the above description, according to the present invention, the rotational speed of a plurality of turbochargers is individually monitored, and the amount of lubricating oil is restricted at low rotational speed according to the operating range of each turbocharger. This makes it possible to appropriately and reliably prevent lubricant oil leakage for each turbocharger having a different operating range.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an engine system showing a first embodiment of the present invention, Fig. 2 is an explanatory diagram of a block of the control circuit of Fig. 1, and Fig. 3 is an explanatory diagram of an engine system showing a second embodiment of the invention. , FIG. 4 is a block diagram of a control circuit similar to that of FIG. 1...engine, 2...intake passage, 5, 6...first,
Second branch intake passage, 3...Exhaust passage, 10, 11...
First and second branch exhaust passages, 8, 9...low speed, high speed turbo supercharger, 8a, 9a...blower, 8b, 9
b...Turbine, 8c, 9c...Rotating shaft, 8d, 9d
...Bearing, 14...Control circuit, 22...Oil pump,
23...Lubricating oil supply path, 24, 24'...Low speed, 1
Next lubricating oil supply path, 25, 25'... High speed, secondary lubricating oil supply path, 26, 27... Low speed, high speed solenoid valve, 28, 29... Rotation sensor, 30, 3
1... Comparison circuit, 39, 40... Primary, secondary turbo supercharger, 44, 45... Rotation sensor, 46, 47... 1
Solenoid valve for next and secondary use.

Claims (1)

[Claims] 1. Includes a plurality of turbo superchargers with different operating ranges,
In a lubricating system for a turbocharged engine that supplies lubricating oil to the rotating shaft of each turbocharger through a branched oil passage branched downstream of an oil pump, each of the plurality of turbochargers multiple rotation detection devices installed in A lubricating oil control device is provided, which controls a corresponding flow control valve to limit the amount of lubricating oil supplied to the turbo supercharger when the rotation speed correspondingly falls below a preset value. Lubricating system for turbocharged engines.