JP2535317Y2 - DOHC engine - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention provides two cylinder heads for an intake valve and an exhaust valve.
The present invention relates to a DOHC engine having three camshafts.

(Prior Art) Conventionally, as shown in FIG. 12 of Japanese Patent Application Laid-Open No. Sho 62-131956, a plurality of support portions for bearing a journal portion of a cam shaft for an intake valve from above on a cylinder head. and a plurality of support portions c for bearing the journal portion of the cam shaft for the exhaust valve from above.
A cam holder e for air intake and exhaust, which is integrally connected to an exhaust side cam holder part d having a cam holder e, is known. In this case, a vertical beam is provided at the center of a rectangular frame f surrounding both the cam holder parts b and d. g are integrally formed, and each of the cam holder portions b and d
Are connected to the vertical beam g via connecting pieces h.

(Problem to be Solved by the Invention) In the above-described conventional device, since the distance between the vertical beam g and each of the support portions a and c is long, the support rigidity of the cam shaft is insufficient at high rotation, and the cam is likely to be formed. The durability of the timing belt that drives the shaft is adversely affected.

In particular, in an engine in which the valve timing can be freely switched between a low speed valve timing and a high speed valve timing,
Since the load fluctuation on the camshaft due to the switching of the valve timing is large, flexural vibration is likely to occur, which adversely affects the durability of the timing belt.

In addition, at the time of high rotation, there is a concern that the lubricating oil of the camshaft and the valve mechanism is insufficient.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an engine that increases the rigidity of a cam holder and improves the lubricity of a cam shaft and a valve operating mechanism to enable high rotation. Is to do.

(Means for Solving the Problems) In order to achieve the above object, according to the invention of claim 1, an intake-side cam holder having a plurality of support portions on a cylinder head for bearing a journal portion of a cam shaft for an intake valve from above. And a cam holder for both intake and exhaust, which is integrally connected to an exhaust side cam holder portion having a plurality of support portions for bearing a journal portion of a cam shaft for an exhaust valve from above, comprising: At least one of the two cam shafts provided with a low-speed cam for low-speed valve timing and a high-speed cam for high-speed valve timing on at least one of the camshafts, so that the valve timing can be switched between low-speed valve timing and high-speed valve timing, A rib is formed on each of the cam holder portions of the cam holder so as to straddle between the support portions of each of the cam holder portions and is located on both sides of each of the cam shafts. An inner surface of each of the ribs on the side of the camshaft is formed as a curved surface along the rotation locus of the cam of each of the camshafts, and is located at the center of each of the ribs of each of the cam holder portions on the cylinder side of each of the intake and exhaust sides. A lubricating oil passage extending in the cam axis direction is formed in the inner rib to be connected, and both cam holder portions are connected to an upstream portion of the lubricating oil passage of the intake side cam holder portion and an upstream portion of the lubricating oil passage of the exhaust side cam holder portion. The lubricating oil supply passage in the cylinder head is connected at the center of the connecting portion, and a passage for cam lubrication directed to the outer surface of the cam of each camshaft is provided on each lubricating oil passage with the inner rib of each cam holder portion. Connected within.

By the way, if a low-speed cam oil path for supplying lubricating oil to the outer surface of the low-speed cam of each camshaft and a high-speed cam oil path for supplying lubricating oil to the outer surface of the high-speed cam of each camshaft are provided, Lubricating oil can be effectively supplied to the low-speed cam and the high-speed cam from separate oil passages, which is advantageous in suppressing the consumption of lubricating oil. In this case, as in the invention of claim 2, one of the oil passages for the low-speed cam oil passage and the high-speed cam oil passage is constituted by the lubricating oil passages formed in the inner ribs. It is preferable that an integral or separate beam member is provided on the cam holder that covers the upper surface of the cam holder portion, and the other of the low-speed cam oil passage and the high-speed cam oil passage is formed in the beam member. .

(Operation) The ribs increase the rigidity of the cam holder, that is, the supporting rigidity of each camshaft, suppress the flexural vibration of each camshaft, and enable high rotation.

Also, since ribs are arranged on both sides of each cam shaft,
The lubricating oil scattered outward by the rotation of the camshaft rebounds on the inner surface of the rib and is supplied again to the outer surface of the cam. In particular, since the inner surface of the rib is formed as a curved surface along the cam rotation trajectory, the re-supply of the lubricating oil to the cam is performed efficiently, and the lubrication of the valve mechanism is improved.

Further, since a lubricating oil passage is formed in the inner rib of each cam holder portion and the rib is also used as a lubricating oil supply member, the valve operating mechanism can be made compact. In this case, it is conceivable to form a lubricating oil passage in the outer rib.However, in this case, the lubricating oil supply passage in the cylinder head is directed inside the cylinder head toward the outer ribs of both the intake and exhaust cam holders. The oil passage must be branched, and the oil passage length increases, the oil passage shape becomes complicated, and the pressure loss increases. On the other hand, in the present invention, the lubricating oil passages formed in the inner ribs of the cam holders on the intake side and the exhaust side are connected to the lubricating oil supply passage in the cylinder head at the center of the connection between the cam holders. Therefore, there is no need to branch the lubricating oil supply passage in the cylinder head, and in combination with the connection of the cam lubrication passage to the lubrication oil passage in the inner rib, the passage from the cylinder head to the cam lubrication passage is eliminated. The length of the oil passage can be minimized, and the lubricating oil can be efficiently supplied to the cam.

Further, if the beam member is provided on the cam holder, the rigidity of the cam holder can be further increased, and the lubricating oil scattered upward by the rotation of the cam shaft hits the lower surface of the beam member and rebounds, or the lubricating oil attached thereto drops. The lubrication of the camshaft and the valve operating mechanism is further improved by being supplied to the outer surface of the cam again.

Providing a cam holder with ribs, ribs, and beam members in an engine that allows the valve timing to be switched between low-speed valve timing and high-speed valve timing can increase camshaft support rigidity and suppress camshaft flex vibration, This is effective in improving the durability of the belt.

When providing a low-speed cam oil passage and a high-speed cam oil passage, it is conceivable to form both oil passages on the inner ribs.
In this case, the strength of the inner rib is greatly reduced, and the rigidity of the cam holder is insufficient. On the other hand, according to the invention of claim 2, the oil passage for the low speed cam and the oil passage for the high speed cam are divided into the inner rib and the beam member, and the strength of the inner rib and the beam member is reduced. It is minimized, and there is no problem such as insufficient rigidity of the cam holder.

(Example) In the drawing, (1) indicates an intake valve (2) for each cylinder of each bank.
6 shows a V-type six-cylinder engine in which a pair of a cylinder and an exhaust valve (3) are provided. A camshaft (5) (6) for an intake valve and an exhaust valve are provided on a cylinder head (4) of each bank. A valve operating mechanism (7) on the valve side and a valve operating mechanism (8) on the exhaust side were provided to constitute a DOHC type engine.

The double-valve mechanisms (7) and (8) have basically the same configuration. Hereinafter, the intake valve-side valve mechanism (7) will be described, and the exhaust-valve-side valve mechanism (8) will be the same. And the description is omitted.

The intake valve side valve mechanism (7) is, as clearly shown in FIG.
A pair of drive rocker arms (10) and (11) for driving a pair of intake valves of each cylinder and a free rocker arm (12) between them are pivotally supported on a rocker shaft (9) for the intake valve. The drive rocker arms (10) and (11) are linked to a low speed cam (5a) formed on a cam shaft for an intake valve, and the free rocker arm (12) is linked to a high speed cam (5b) formed on the cam shaft. The rocker arms (10) and (11) are connected to the free rocker arm (12) via a switching mechanism (13) so as to be freely connected and disconnected. The drive rocker arms (10) and (11) and the free rocker arm (12) In the non-connected state, the intake valve is opened and closed by the low-speed cam (5a) at a low valve timing with the valve opening period and the lift amount relatively small. In the connected state, the valve opening period and the lift amount are controlled by the high-speed cam (5b). With high-speed valve timing with relatively large The intake valve is opened and closed.

The switching mechanism (13) includes a first connecting pin (13a) which is detachably engageable with a free rocker arm (12) inserted into one first drive rocker arm (10), and a second connecting pin (13) inserted into the free rocker arm (12). A second connecting pin (13b) detachable from the second drive rocker arm (11) of the second drive rocker arm (11);
A regulating pin (13d) which is urged toward the free rocker arm (12) by a spring (13c) inserted in 1).
A hydraulic chamber (13e) for pressing the first connecting pin (13a) toward the free rocker arm (12) is formed in the drive rocker arm (10), and the hydraulic chamber (13e) is formed on a rocker shaft (9). (14) and the oil supply passage (1) to the hydraulic chamber (13e).
When pressurized oil is supplied via 4), the first connecting pin (13
a) engages with the free rocker arm (12), and is pushed by the first connecting pin (13a) so that the second connecting pin (13b) engages with the second drive rocker arm (11). 10) (11) and the free rocker arm (12) are connected to switch the valve timing to the high-speed valve timing, and when the hydraulic pressure in the hydraulic chamber (13e) decreases, the spring (13)
The second connecting pin (13b) and the first connecting pin (13a) are pushed back into the free rocker arm (12) and the first drive rocker arm (10) via the regulating pin (13d) by the biasing force of c). Then, the connection between the drive rocker arms (10) and (11) and the free rocker arm (12) is released, and the valve timing is switched to the low-speed valve timing.

Then, the oil supply passage (14) is connected to an oil passage (15) for supplying oil from an oil pump (not shown) via respective switching valves (16) attached to the ends of the cylinder heads of the respective banks. When the spool valve body (16a) of the switching valve (16) is in the upper closed position, the inflow port (16b) connected to the oil path (16) via the oil filter (17) and the oil supply path (14) are connected. The outflow port (16c) communicates only through the orifice hole (16d), and the outflow port (16c) communicates with the drain port (16e) that opens into the upper space of the cylinder head. Although the hydraulic pressure decreases, when the spool valve element (16a) is switched to the lower open position, the inflow port (16b) and the outflow port (16c) are connected to the spool valve element (16a).
a) and the outflow port (16
The communication between c) and the drain port (16e) was cut off, and the oil pressure in the oil supply passage (14) was increased.

The spool valve element (16a) is switched to an open position against a spring (16f) by a pilot pressure input through a pilot oil passage (18) branched from an inflow port (16b). When a normally closed solenoid valve (19) is interposed in the oil passage (18) and the solenoid valve (19) is opened by energizing the solenoid of the solenoid valve (19), the spool valve body (16a ) Is switched to the open position, the valve timing is switched to the high-speed valve timing as described above, and when energization of the solenoid is stopped to close the solenoid valve (19), the spool valve body (16a) closes. The valve timing is switched to the low-speed valve timing by switching to the position.

Also, to confirm the switching operation of the spool valve element (16a),
Outflow port (16c) in housing (16g) of switching valve (16)
A hydraulic switch (20) is provided to detect the hydraulic pressure and turn on when the pressure is low and turn off when the pressure is high.

In the figure, (6a) is a low-speed cam formed on a cam shaft (6) for an exhaust valve, and (6b) is a high-speed cam.

The camshafts (5) and (6) are driven by one timing belt (21), and the cylinder head (4) of each bank is provided with a journal portion of a camshaft (5) for an intake valve (2). Cam holder (23) having a plurality of support portions (22) for bearing the bearing from above, and a plurality of support portions (24) for bearing the journal portion of the cam shaft (6) for the exhaust valve (3) from above. A plurality of cam holders (27) for air intake and exhaust, which are integrally connected to an exhaust side cam holder part (25) having a plurality of connecting parts (26), are attached.
In 5), ribs (28) located on both sides of the camshafts (5) and (6) are straddled between the support portions (22) and (24) of the cam holder portions (23) and (25). And the inner surfaces of the ribs (28) are connected to the cams (5a) (5b) (6a) of the camshafts (5) and (6).
It was formed on a curved surface along the rotation locus of (6b).

Then, a beam member (29) separate from the cam holder (27) that covers the cam holder portions (23) (25) from above.
The beam members (29) were placed on the cam holder (27) and fixed together to the cylinder head (4) with a plurality of bolts (30).

Each rib (2) on the inner side of each cam holder (23) (25)
In 8), dual-purpose oil passages (31) and (31) extending in the longitudinal direction are respectively formed, and the respective cam holder portions (23) and (25) are formed.
Each support part (22) of each cam holder part (23) (25)
The passage (32) opening on the bearing surface of (24) and each of the cams (5)
a) A passage (33) directed to the outer surface of (5b), (6a), and (6b) is bored in communication with each of the oil passages (31), and the cam holder (2
As shown in FIG. 8, a passage (34) communicating with the oil passages (31) and (31) is provided at the right end connecting portion (26) in FIG. An opening is provided on the lower surface of the holder (27), and thus lubricating oil from the cylinder head (4) side is journaled to the intake valve cam shaft (5) and each of the cams (5a) (5
These passages (32) are formed between the outer peripheral surface of b) and the outer peripheral surfaces of the journal portion of the exhaust valve cam shaft (6) and the cams (6a) (6b).
(33) It is made possible to supply the oil through (34) and the respective oil passages (31).

As shown in FIGS. 5 and 10, a plurality of oil passages (35) extending in the longitudinal direction are formed in each of the beam members (29), and a plurality of openings are formed on the lower surface of each of the beam members (29). A passage (36) is drilled so as to communicate with the oil passage (35) so that lubricating oil can be supplied to the outer peripheral surfaces of the high-speed cams (5b) and (6b) of the respective camshafts (5) and (6). did.

In this case, the oil passages (31) and (6) supply lubricating oil to the journals of the camshafts (5) and (6) and the cams (5a) (5b) (6a) (6b) through the oil passage (35). 31) may be connected through a passage so that a relatively high-pressure lubricating oil is always supplied to the oil passage (35) during operation of the engine. 9), a first passage (36a) opening on the lower surface of the left end portion, and the first passage (36a) at the left end portion of each cam holder portion (23) (25) of the cam holder (27) as clearly shown in FIG. And a second passage (36b) connected to
The downstream end of the oil supply passage (14) for supplying oil to the hydraulic chamber (13a) of the switching mechanism (13) is communicated with the second passage (36b). The relatively low-pressure lubricating oil is used during operation at high speed and the relatively high-pressure lubricating oil is used during high-speed valve timing.
5) through the first and second passages (36a) and (36b), so that the consumption of lubricating oil is suppressed and the power loss by the oil pump can be suppressed as much as possible.

In the drawing, (37) shows an adjustment window of the valve clearance adjustment screw (38) formed on the rib (28) outside the cam holder.

In the embodiment, each beam member (29) is connected to the cam holder (2
Although it is formed separately from 7), it can be formed integrally with the cam holder (27). The low-speed cams (5a) (6a) of the respective cam shafts (5) and (6) can be formed on the beam member (29). A low-speed cam oil passage for supplying lubricating oil may be provided.

In the above embodiment, the ribs (2
8) Use the cam shafts (5) and (6) for the journal section and each cam (5).
a) One common passageway (31) for (5b), (6a), and (6b) was drilled, but the invention is not limited to this. The oil passage for the journal and the cam oil are provided in the rib (28). The passages (32) formed in the support portions (22) and (24) can be formed separately in the rotation direction of the camshafts (5) and (6). The lubricating oil to be supplied is formed so as to be opened at the position where the lubricating oil is discharged in the clockwise direction in FIG. 8, that is, in the embodiment, at the right end of the bearing surface of each support portion (22) (24). Advantageously, the rotation of (5) and (6) facilitates retraction and the lubrication of the journal portions of the camshafts (5) and (6) is improved.

(Effects of the Invention) According to the invention of the first aspect, since the support rigidity of the camshaft is increased by the rib, the durability of the timing belt in the engine in which the valve timing can be switched can be improved, and the rib can be used. Since it can also be used as a lubricating oil supply member, it is possible to reduce the size of the entire valve mechanism, increase the efficiency of lubricating oil resupply by rebounding on the inner surface of the rib, and provide a passage for cam lubrication from the cylinder head. Has the effect of minimizing the length of the oil passage leading to the lubrication and improving the lubricity as much as possible.

Further, according to the invention of claim 2, it is possible to effectively supply the lubricating oil to the low-speed cam and the high-speed cam, and to minimize the strength decrease due to the oil passage, and to increase the support rigidity of the cam shaft as much as possible. It has an effect that can be improved.

[Brief description of the drawings]

1 to 11 show the engine of the present invention.
FIG. 2 is a front view of a V-type engine, FIG. 2 is a plan view of a cylinder head of a left bank thereof, and FIGS. 3 to 5 are III-III, IV-IV, and V-V lines of FIG. Sectional view, line 6
7 is a plan view of the cam holder, FIG. 7 is a bottom view thereof, FIGS. 8 and 9 are sectional views taken along lines VII-VII and IX-IX of FIG. 6, respectively, and FIG. 10 is a bottom view of the beam member. FIG. 11 is a view showing a valve switching mechanism, and FIG. 12 is a plan view of a conventional cam holder. (2) ... intake valve, (3) ... exhaust valve (4) ... cylinder head, (5) (6) ... cam shaft (5a) (6a) ... low-speed cam, (5b (6b) ... ... High-speed cam (22) (24) ... Support (23) ... Intake side cam holder (25) ... Exhaust side cam holder (27) ... Cam holder, (28) ... Rib (29) ... Beam Members, (31) (35) ... oil passage

Claims (2)

(57) [Scope of request for utility model registration] An intake side cam holder portion having a plurality of support portions for bearing a journal portion of a camshaft for an intake valve from above on a cylinder head, and a plurality of bearing portions for bearing a journal portion of a camshaft for an exhaust valve from above. A DOHC engine equipped with an intake / exhaust cam holder integrally connected to an exhaust-side cam holder portion having a support portion, wherein the low-speed cam for low-speed valve timing is provided on at least one of the two cam shafts. And a high-speed cam for high-speed valve timing,
In a valve in which the valve timing can be switched between a low-speed valve timing and a high-speed valve timing, each of the cam holders of the cam holder is straddled between each of the support portions of each of the cam holders. Forming ribs, and forming the inner surfaces of the respective ribs on the respective camshaft sides into curved surfaces along the rotation trajectory of the cams of the respective camshafts; A lubricating oil passage extending in the cam axis direction is formed in an inner rib positioned on the center side of the cylinder, and an upstream portion of the lubricating oil passage of the intake cam holder portion and an upstream portion of the lubricating oil passage of the exhaust cam holder portion. Is connected to the lubricating oil supply passage in the cylinder head at the center of the connecting portion connecting the two cam holder portions, and a cam lubrication passage directed to the outer surface of the cam of each camshaft is provided to each lubricating oil passage in each cam holder. In front of the department DOHC type engine, characterized in that connected in the inside of the rib. 2. A high-speed cam oil passage for supplying lubricating oil to an outer surface of a low-speed cam of each camshaft, and a high-speed cam oil passage for supplying lubricating oil to an outer surface of a high-speed cam of each camshaft. One of the low-speed cam oil passage and the high-speed cam oil passage is constituted by the lubricating oil passage formed in the inner rib,
An integral or separate beam member is provided on the cam holder that covers the upper surface of each of the cam holder portions, and the other of the low-speed cam oil passage and the high-speed cam oil passage is formed in the beam member. The DOHC engine according to claim 1, wherein: