JPS5916511Y2 - Separate supercharged engine - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to improvements in separately supercharged engines.

In order to improve the operating fuel efficiency of automobiles, it is a good idea to increase the efficiency of the engine and make it smaller and lighter.

For this reason, supercharging technology using turbochargers has been attracting attention recently, but conventional superchargers supercharge the entire intake air volume of the engine, so the supercharger has a large capacity and has a large drive loss. In low speed ranges, the supercharging rate was small and not necessarily sufficient, making it difficult to match it with practical vehicles.

On the other hand, as a separate supercharged engine, one cylinder of an engine with multiple cylinders is operated as a compressor,
An engine has been proposed in which the discharged air-fuel mixture is supercharged to a power cylinder through a supercharging passage separate from an intake passage (for example, see Japanese Patent Laid-Open No. 105514/1983).

The compressor, which reciprocates with the power cylinder via the crankshaft, performs one discharge action per crank rotation, and after the suction stroke is completed, the third valve in the supercharging passage is opened to create a pressurized mixture. Since air is additionally introduced into the cylinder, there is an advantage that not only can the substantial intake air filling efficiency be increased with a small-capacity compressor, but also a sufficient supercharging rate can be obtained even at low speeds.

However, with this type of separate supercharging system, there is a limit to the supercharging rate when the engine is running at high speed, and there is a problem that the output performance from the medium speed range to the limit speed range does not improve as much as expected. Ta.

This is mainly due to the fact that the higher the flow velocity of the supercharging air when it is additionally introduced into the cylinder, the closer it approaches the speed of sound, and it is difficult to increase any higher than that.

Also, if you increase the lift of the third valve,
Inevitably, the opening time of the third valve becomes longer and the third valve is significantly involved in the compression stroke, which in turn causes a problem of insufficient compression pressure at low speeds, resulting in a decrease in output.

This invention was developed with a focus on these problems.
The third valve is driven via a variable lifter device that expands and contracts according to the engine oil pressure, and the lift of the third valve increases as the engine speeds up. This solves the above-mentioned conventional problems, and also enables high-speed, high-load operation. The present invention provides a separately supercharged engine that improves engine durability over time.

The present invention will be explained below based on the embodiments shown in FIGS. 1 and 2.

Figure 1 shows one cylinder of an engine with five cylinders as compressor (pump cylinder) 1, and four power cylinders #1 to #.
4 represents an embodiment of a separate supercharged engine that drives this.

The suction port 1a of the pump cylinder 1 and the intake passage 2 that guide intake air to each of the power cylinders #1 to #4 are connected, and the discharge port 1b of the pump cylinder 1 and each of the power cylinders #1 to #4 are connected to the intake passage 2. A supercharging passage 3 is provided which is connected to the supercharging passage 3 independently, and a part of the intake air from the intake passage 2 is force-fed to the supercharging passage 3, and is additionally introduced into the power cylinders #1 to #4.

For this reason, each power cylinder #1 to #4 is provided with a third valve 4 for opening and closing the supercharging passage 3, but the opening timing of this third valve 4 is as described above. ,
Basically, the valve is set to open from near the end of the intake stroke to midway through the compression stroke.

Further, 5 is an intake valve for opening and closing the intake passage 2, and 6 is an exhaust valve for opening and closing the exhaust passage 7.
A similar suction valve 8 and discharge valve 9 are also provided, and a suction-discharge operation is performed every revolution of the crank.

By the way, the third valve 4 is driven via a valve lift control device 10 shown in FIG.

The valve lift control device 10 has already been proposed by the applicant as a device that changes the lift and timing of intake and exhaust valves using engine oil pressure (
For example, Japanese Patent Application No. 54-74994).

To explain this, as shown in the figure, the valve lift control device 10 includes a cam 11 that rotates in synchronization with the engine, a variable lid device 12, a bushing rod 13, a swing cam 14, a rocker arm 15, and the like.

The swing cam 14 has a cam surface 16 that protrudes toward the side pushed up by the bushing rod 13, and a pace circuit 17 thereof.
It is formed with a gentle curve starting from the rising part 18 from the position shown in the figure, and when it is rotated clockwise from the position shown in the figure, the driven end 19 of the rocker arm 15 is gradually pushed up via the cam surface 16, and when it is rotated counterclockwise, the driven end 19 of the rocker arm 15 is pushed up toward the base circle 17. The rocker arm 15 is formed in such a way that it continues to be in contact with the rocker arm 15 and does not give rocker arm 15 any rocking motion.

In other words, the more margin the swing cam 16 has in the clockwise rotation angle until its rising portion 18 comes into contact with the driven end 19 of the rocker arm 15, the later the rocker arm 15 starts to swing.

On the other hand, the variable lid device 12 includes a tappet l-20 that follows the cam 11 and a piston 21 that is slidably housed in the tappet 20 and comes into contact with the bushing rod 13. The second hydraulic pressure is supplied to the hydraulic chamber 25 of the piston 21 through communication holes 23 and 24 provided in each, and further to the tapetsu l-20 via a check valve 26 provided at the bottom of the piston 21. room 2
It is configured so that it can be introduced into 7.

Furthermore, a small piston 29 with a hydraulic pressure relief rod 28 protruding so as to face the check valve 26 is housed in the first hydraulic chamber 25, and this small piston 29 is supported by a coil spring 30 installed behind it. It is urged downward based on the force generated.

Furthermore, a coil spring 31 is also interposed in the second hydraulic chamber 27 to exert a force that pushes the piston 21 upward, and a return spring that biases the swing cam 14 to rotate counterclockwise. 320 resilient force opposes and brings the bushing rod 13 into contact with the piston 21.

Now, when a certain amount of hydraulic pressure acts on the variable lifter device 12 via the hydraulic passage 22, the hydraulic oil flows into the
Then, push open the check valve 26 to open the second hydraulic chamber 2.
7 and pushes up the piston 21.

The amount of rise of this piston 21 with respect to the tappets) 20 is:
It is determined depending on the hydraulic pressure and the balance between the elastic force of the coil spring 31 and the elastic force of the return spring 32. Therefore, as the oil pressure increases, the amount of rise of the piston 21 increases. Rotate clockwise.

However, when the piston 21 rises to a certain extent, the communication hole 24 closes, and both hydraulic chambers 25 and 27 enter an oil lock state, thereby restricting the piston 21 from rising any further.

On the other hand, when the oil pressure decreases, the elastic force of the coil spring 30 becomes dominant over the hydraulic oil pressure in the first hydraulic chamber 25.
The small piston 29 descends and forcibly opens the check valve 26 via the hydraulic relief rod 28.

As a result, the hydraulic fluid in the second hydraulic chamber 27 is transferred to the first hydraulic chamber 2.
5. The piston 21 further escapes to the hydraulic passage 22.
quickly descends within the tappet 20.

In this way, the effective length of the variable lid device 12 increases as the hydraulic pressure from the hydraulic passage 22 increases, shifting the initial phase of the swing cam 14 clockwise, and the effective length decreases as the hydraulic pressure decreases. to shift the initial phase of the swing cam 14 counterclockwise.

The third valve 4 is set to open when pushed by the swing end 33 of the rocker arm 15, and engine oil pressure is supplied to the hydraulic passage 22.

Since engine oil pressure increases approximately in proportion to engine speed,
As mentioned above, the more the engine speed increases, the more the oscillating cam 1
4, the lift of the fourth valve 4 increases.

When the lift of the third valve 4 is expanded in this way, the passage area of the supercharging airflow from the supercharging passage 3 increases, and the flow rate increases without increasing the flow velocity, so even at high speeds. A sufficient supercharging effect can be obtained.

Of course, since the lift of the third valve 4 is relatively small in the low speed rotation range, the problem of insufficient compression pressure at low speeds does not occur.

The present invention also aims to improve engine durability by suspending supercharging during high-speed, high-load operation.

For this purpose, as shown in FIG. 1, a hydraulic pressure relief valve (electromagnetic switching valve) 34 is installed in the middle of the hydraulic passage 22 on the upstream side of each valve lift control device 10. (For example, to the atmosphere) Boost pressure relief valve (electromagnetic switching valve)
35 is provided in the supercharging passage 3.

Both relief valves 34 , 35 are configured to be switched synchronously in response to a signal voltage from a control circuit 36 .

The control circuit 36 detects the rotational speed and load condition based on the engine rotational speed signal and the load signal, controls the signal voltage to both relief valves 34 and 35, and brings the engine into a predetermined high-speed, high-load operating state. and switches both relief valves 34 and 35.

As a device for providing a rotational speed signal to the control circuit 36,
For example, a crank angle sensor, an intake pressure sensor, an air flow meter, etc. are suitable as a device for providing a load signal (not shown).

Note that the valve lift control device 10 is set so as not to apply a lift to the third valve 4 when the engine oil pressure is not applied.

For this purpose, as is clear from what has already been explained, even if the variable lid device 12 is lifted to its maximum, the swing cam 1
The initial phase of the swing cam 14 should be determined so that the rocker arm 4 does not push up the rocker arm 15 (FIG. 2).

Next, the action will be further explained.

As mentioned above, the higher the engine operating speed, the more
The lift of the valve 4 is expanded and a sufficient supercharging rate is obtained up to the high speed range, but under engine operating conditions where the speed is higher than the predetermined value and the load is large, the control circuit 36
The hydraulic pressure relief valve 34 and the supercharging pressure relief valve 35 are switched simultaneously to release the hydraulic pressure of the valve lift control device 10 and open the supercharging passage 3 to, for example, the atmosphere.

As a result, the third valve 4 maintains a zero lift, that is, a closed state, and the supercharged air discharged from the pump cylinder 1 during this period escapes, for example, to the outside via the relief valve 35.

In this way, under high-speed, high-load conditions, that is, high-load operation near the engine's limit rotational speed, supercharging is suspended, so the combustion pressure is moderately suppressed, reducing the mechanical load on each part of the engine, and thus reducing engine speed. Durability is significantly improved.

Furthermore, it has the effect of avoiding engine overspeed caused by driver error.

As described above, according to the present invention, it is possible to improve the supercharging effect in the medium to high speed range of the separately supercharged engine, thereby improving the output performance, and also to improve the durability of the engine.

In addition, in the above embodiment, when driving the third valve,
Although a valve lift control device was installed in the OHV model, it would be possible to use the OHV model by installing a variable lid device or a swinging cam approximately horizontally.
It is also possible to configure it in a C type.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing an embodiment of the present invention, and FIG. 2 is a sectional view of the valve lift control device viewed from the front of the engine. 1... Compressor (pump cylinder), 2... Intake passage, 3... Supercharging passage, 4... Third valve, 5... Intake valve, 6... Exhaust valve, 10...・Valve lift control device, 11... cam, 12... variable lifter device, 13.
... Butsch rod, 14... Rocking cam, 15...
Rocker arm, 22... Hydraulic passage, 34... Hydraulic pressure relief valve (three-way solenoid valve), 35... Supercharging pressure relief valve (three-way solenoid valve, 36... Control circuit, #L #2. #3 ．＃
4...Power cylinder.

Claims (1)

[Claims for Utility Model Registration] 1. A supercharging passage that is independent of the engine intake passage and connected to the supercharger, and a third passage that additionally introduces supercharging air from the supercharging passage into the cylinder.
In a separately supercharged engine equipped with a valve, a valve lift control device is provided that changes the lift of the third valve in response to engine oil pressure, and as the engine rotational speed increases, the lift of the third valve increases.
A separately supercharged engine characterized by expanding the valve lift. 2. A hydraulic pressure relief valve is provided to release the hydraulic pressure of the third valve when the valve lift control device is in a high-speed, high-load operating state exceeding a predetermined value, and supercharging is suspended in the high-speed, high-load operating region. A separately supercharged engine according to claim 1 of the utility model registration claim.