JP2007071040A - Cylinder head structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain rotational friction of a timing chain by a large quantity of oil flowing in from above a cylinder head by making fresh air uniformly flow in an engine from an introducing port opening in a space between the cylinder head and a cylinder head cover. <P>SOLUTION: A fresh air introducing port 51 for introducing the fresh air provided for ventilation inside of the engine 1 and exhausted from a lower part of the engine, is opened in the space 10 between the cylinder head 13 and the cylinder head cover 14. A chain case having an upper end part communicating with the space is arranged on one side of the engine. A dam 52 is arranged on the anti-chain case side surface of a cam cap 23 positioned on the most chain case side in the space. An orifice passage 53 is formed in an upper end part of its dam for adjusting a flow rate to the chain case side of the fresh air introduced into the space from the fresh air introducing port. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cylinder head structure in which an introduction port for introducing fresh air that is used for ventilation inside an in-line engine or a V-type engine and exhausted from the engine is provided in the cylinder head. It relates to measures to ensure that fresh air introduced from the inlet can flow uniformly into the engine.

  Conventionally, an inlet for introducing fresh air is provided in the space between the cylinder head and the cylinder head cover of the engine, and the fresh air introduced from the inlet is guided to the lower part of the engine. It is known that the blow-by gas discharged from the inside of the case is discharged from an exhaust opening that opens into the space while reducing the concentration of the blow-by gas (for example, see Patent Document 1).

In this case, a chain case whose upper end communicates with the space between the cylinder head and the cylinder head cover is provided on one side of the engine, and fins are provided on the cam sprockets in the chain case, so that the engine The flow of fresh air in the space introduced from the side introduction port is actively guided to the chain case side without being led to the exhaust port on the other side of the engine.
JP-A-8-326520

  However, in the above conventional one, most of the flow of fresh air introduced from the introduction port is guided to the chain case side (one side of the engine) by the cam sprocket fins in the chain case. The fresh air is not evenly guided in the space between the two and the fresh air is not sufficiently guided to the lower part of the engine, so that the fresh air from the inlet cannot flow uniformly into the engine.

  On the other hand, the cylinder head and the cylinder block are provided with oil return holes for returning the oil to the oil pan through the cylinder head and the cylinder block in the vertical direction, but between the cylinder head and the cylinder head cover. Since the upper end portion of the chain case communicates with the space, most of the oil used for lubrication of the camshaft or the like in the space easily flows into the chain case side with the flow of fresh air. Therefore, a large amount of oil that flows into the chain case from above the cylinder head increases the rotational friction of the chain.

  The present invention has been made in view of such points, and the object of the present invention is to allow fresh air from an inlet opening in a space between the cylinder head and the cylinder head cover to flow uniformly into the engine. Another object of the present invention is to provide a cylinder head structure capable of suppressing the rotational friction of the chain in the chain case due to a large amount of oil flowing from above the cylinder head.

  In order to achieve the above object, according to the present invention, an inlet for introducing fresh air that is used for ventilation inside the engine and exhausted from the lower part of the engine is opened in a space between the cylinder head and the cylinder head cover. On the premise of the cylinder head structure, a chain case having an upper end communicating with the space is provided on one side of the engine. Then, a weir for blocking outflow of oil in the space to the chain case side is provided at the chain case side end on the cylinder head, and the upper end of the weir is introduced into the space from the introduction port. A throttle passage that adjusts the flow rate of fresh air to the chain case is formed.

  Due to this specific matter, fresh air introduced from the introduction port into the space between the cylinder head and the cylinder head cover is brought into the chain case side by the throttle passage at the upper end of the weir at the chain case side end on the cylinder head. The flow rate will be adjusted. As a result, most of the flow of fresh air will not be guided to the chain case side, and it will be tuned smoothly, and fresh air introduced into the space between the cylinder head and the cylinder head cover will be placed in the lower part of the engine. It is sufficiently guided to allow the fresh air from the inlet to flow uniformly into the engine.

  In addition, fresh air from the introduction port flows uniformly in the space between the cylinder head and the cylinder head cover, so that fresh air is evenly introduced into the cylinder head cover, and condensation forms on the inner surface of the cylinder head cover when it is cold. The generation of nitric acid due to the reaction between dew condensation (condensed water) and NOx is suppressed, and mixing of nitric acid into the oil is also suppressed, so that the life of the oil can be extended efficiently.

  Furthermore, most of the oil used for lubrication of the camshaft and the like in the space between the cylinder head and the cylinder head cover is securely blocked without flowing into the chain case side by the weir at the chain case side end on the cylinder head. Thus, the cylinder head and the oil return hole penetrating the cylinder head in the vertical direction are returned to the oil pan, and the rotational friction of the chain due to a large amount of oil in the chain case can be reduced. .

  In order to achieve the above object, the present invention also refers to a configuration unique to the V-type engine.

  In other words, the inlet for introducing fresh air that is used for ventilation inside the V-type engine and exhausted from the cylinder head of one bank of the V-type engine is connected to the cylinder head of the other bank of the V-type engine. Assuming a cylinder head structure that opens into the space between the cylinder head cover, a chain case with an upper end communicating with the space between the cylinder heads of both banks and the cylinder head cover is provided on one side of the V-type engine. Provide. In addition, a weir for blocking outflow of oil in the space of both banks to the chain case side is provided at each end of the chain case on the cylinder head of both banks, and the other bank of the weirs is provided. A throttle passage for adjusting the flow rate of fresh air introduced from the introduction port into the space to the chain case side is formed at the upper end of the side weir.

  Also in this specific matter, the fresh air introduced from the introduction port into the space between the cylinder head and the cylinder head cover of the other bank of the V-type engine is in the upper end of the weir at the side end of the chain case in the space. The flow rate to the chain case side is adjusted by the throttle passage. As a result, most of the fresh air flow is not exhausted from the space between the cylinder head and the cylinder head cover of one bank via the chain case, and the tuning is smoothly performed. The fresh air from the space between the cylinder head and the cylinder head cover of the other bank is sufficiently guided to the lower part of the V-type engine, and the fresh air from the inlet can flow uniformly into the V-type engine. Become.

  Further, most of the oil used for lubrication of the camshaft or the like in the space between the cylinder head and the cylinder head cover of each bank flows into the chain case side by the weir at the chain case side end on the cylinder head of each bank. It can be reliably dammed and returned to the oil pan through the oil return hole on the cylinder head of each bank, reducing the rotational friction of the chain due to a large amount of oil in the chain case. It becomes.

  In particular, the following configurations are listed as specifying the weir.

  That is, the weir is provided in the cam cap located closest to the chain case in the space between the cylinder head and the cylinder head cover.

  Due to this specific matter, the weir is formed using the cam cap, and it is possible to form the weir at a lower cost compared to the case where it is newly formed.

  In short, by providing a weir at the chain case side end on the cylinder head and forming a throttle passage that adjusts the flow rate of fresh air at the upper end of the weir, smooth flow of fresh air to the chain case side is achieved. Tuning allows the fresh air from the inlet to flow uniformly into the engine, and also prevents the formation of dew condensation on the inner surface of the cylinder head cover during cold weather, etc. Can effectively extend the service life. Furthermore, the oil flow into the chain case side can be reliably blocked, and the rotational friction of the chain due to a large amount of oil in the chain case can be reduced.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a DOHC type in-line four-cylinder engine 1 to which a cylinder head structure according to Embodiment 1 of the present invention is applied, partially cut away when viewed from the side perpendicular to the axis of a crankshaft 11. .

  As shown in FIG. 1, an in-line four-cylinder engine 1 (hereinafter simply referred to as an engine) includes a cylinder head 13 disposed on the upper side of a cylinder block 12. A cylinder head cover 14 is disposed above the cylinder head 13. An oil pan 15 is disposed at the lower end of the cylinder block 12, and the crankshaft 11 is rotatably supported. In this case, a space 10 is formed between the cylinder head 13 and the cylinder head cover 14.

  As shown in FIG. 2, on the cylinder head 13, a substantially semi-circular bearing portion that supports the intake camshaft 21 and the exhaust camshaft 22 from the lower side at predetermined intervals in the axial direction of the crankshaft 11. 13a (see FIG. 2) is provided, and each bearing portion 13a has a cam cap 23 having a substantially semicircular arc-shaped bearing portion 23a that individually supports the intake camshaft 21 and the exhaust camshaft 22 from above. Are fastened by a pair of bolts 24, 24. The intake camshaft 21 and the exhaust camshaft 22 are rotatably supported by bearings 13a of the cylinder head 13 and bearings 23a of the cam caps 23 via bearings. In FIG. 2, 21a is an intake cam, and 22a is an exhaust cam.

  Further, as shown in FIG. 1, a chain case 3 is attached to one side of the engine 1 (left side in FIG. 1). The chain case 3 has an upper end communicating with one side of a space 10 (hereinafter simply referred to as a space) between the cylinder head 13 and the cylinder head cover 14, and a lower end being a lower portion of the cylinder block 12. Communicating with In the chain case 3, a crank sprocket 31 rotatably connected to the tip of the crankshaft 11 protruding from one side of the cylinder block 12, an intake camshaft 21 protruding from one side of the cylinder head 13, and A cam sprocket 32 (only an intake cam sprocket is shown in FIG. 1) that is connected to the tip of the exhaust camshaft 22 in a rotationally integrated manner, and a timing chain 33 wound around the crank sprocket 31 and each cam sprocket 32. And is housed.

  The engine 1 includes a blow-by gas reduction device 4 (hereinafter referred to as a PCV (Positive Crankcase Ventilation) device) that guides the blow-by gas blown into the crank chamber from the gap between the inner surface of the cylinder and the outer surface of the piston to the intake system. . The PCV device 4 includes an oil separator 41 disposed on the side surface of the cylinder block 12. The oil separator 41 includes a separator case 42, a blow-by gas introduction hose 43, an oil discharge hose, and a blow-by gas discharge hose 45 connected to the separator case 42. Each will be described below.

  The separator case 42 is for separating the oil mist from the blow-by gas extracted from the crank chamber at the lower part of the cylinder block 12 by the blow-by gas introduction hose 43, and is attached to the side surface of the cylinder block 12 by means such as bolting. It is attached. The separator case 42 is connected to the downstream end of the blow-by gas introduction hose 43. The upstream end of the blow-by gas introduction hose 43 is opened in the crank chamber below the cylinder block 12 so that the blow-by gas blown into the crank chamber is extracted and introduced into the separator case 42. In addition, an oil discharge hose is connected to the separator case 42, and the oil separated in the separator case 42 is returned to the oil pan 15 through the oil discharge hose.

  The blow-by gas discharge hose 45 is a pipe for guiding the blow-by gas after the oil is separated and removed in the separator case 42 to the intake system, the downstream end is connected to the surge tank, the blow-by gas is removed from the surge tank Through the intake system of the engine 1. A PCV valve 46 is provided at the upstream end of the blow-by gas discharge hose 45. When the PCV valve 46 is opened due to intake negative pressure or the like, the blow-by gas in the separator case 42 flows out into the blow-by gas discharge hose 45 and is introduced into the surge tank.

  The cylinder head cover 14 is provided with a fresh air inlet 51 as an inlet for introducing fresh air to be ventilated in the engine 1. The fresh air introduced into the space 10 from the fresh air inlet 51 is discharged together with the blow-by gas from the upstream end of the blow-by gas introduction hose 43, and the fresh air discharged together with the blow-by gas is separated from the separator case 42 and the blow-by gas. It is introduced into the surge tank via the discharge hose 45.

  Further, the cylinder head 13 and the cylinder block 12 are provided with a plurality of oil return holes 16, 16,... Penetrating through the cylinder head 13 and the cylinder block 12 in the vertical direction. The oil return holes 16 are for returning oil used for lubrication of the camshafts 21 and 22 to the oil pan 15. The fresh air introduced from the fresh air introduction port 51 is supplied to the cylinder block 12. It is also used as a passage for guiding into the lower crankcase.

  As a characteristic part of the present invention, as shown in FIG. 2, the anti-chain case of the cam cap 23 located closest to the chain case 3 (left side in FIG. 1) in the space 10 among the cam caps 23. On the three side surfaces, there is provided a weir 52 that protrudes upward from the upper end surface of the cylinder head 13 so as to block outflow of oil used for lubricating the camshafts 21 and 22 to the chain case 3 side in the space 10. It has been. A throttle passage 53 for adjusting the flow rate of fresh air introduced from the fresh air inlet 51 into the space 10 toward the chain case 3 is formed at the upper end of the weir 52. The throttle passage 53 is formed between the inner surface of the cylinder head cover 14 and the upper end surface of the weir 52.

  Therefore, in the first embodiment, the fresh air introduced into the space 10 from the fresh air inlet 51 of the cylinder head cover 14 is the side of the chain cap 3 opposite to the chain cap 3 located in the space 10 on the most side of the chain case 3. The flow rate to the chain case 3 side is adjusted by the throttle passage 53 at the upper end of the weir 52 protruding upward from the upper end surface of the cylinder head 13. As a result, most of the flow of fresh air in the space 10 is not led to the chain case 3 side and is tuned smoothly, so that fresh air introduced from the fresh air inlet 51 of the cylinder head 13 is The fresh air from the fresh air inlet 51 can be made to flow uniformly into the engine 1 by being sufficiently guided into the crankcase below the cylinder block 12 via the oil return holes 16 and the chain case 3.

  In addition, since fresh air from the fresh air inlet 51 flows uniformly in the space 10, fresh air is evenly introduced into the cylinder head cover 14, and condensation does not easily occur on the inner surface of the cylinder head cover 14 when it is cold. Thus, the production of nitric acid due to the reaction between condensation (condensed water) and NOx is also suppressed, and the mixing of nitric acid into the oil is also suppressed, so that the life of the oil can be effectively extended.

  Most of the oil used for lubrication of the cam shafts 21, 22, etc. in the cylinder head 13 is above the upper end surface of the cylinder head 13 on the side opposite to the chain case 3 of the cam cap 23 located closest to the chain case 3. The weir 52 protruding to the side of the chain case 3 is surely dammed and returned to the oil pan 15 through each oil return hole 16, and timing due to a large amount of oil in the chain case 3 The rotational friction of the chain 33 can be reduced.

  Furthermore, by providing the weir 52 on the side opposite to the chain case 3 of the cam cap 23 located closest to the chain case 3 in the space 10, the weir 52 is formed using the cam cap 23. The weir 52 can be formed at a lower cost as compared with the case of forming it.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the second embodiment, the cylinder head structure according to the present invention is applied to a DOHC type V-type engine.

  That is, in the present embodiment, the V-type engine 6 (hereinafter simply referred to as the engine) has a pair of banks 62L and 62R protruding in a V-shape at the top of the cylinder block 61. Each bank 62L, 62R includes a cylinder head 63L, 63R installed at the upper end of the cylinder block 61, and a cylinder head cover 64L, 64R attached to the upper end thereof. A crankcase 65 is attached to the lower side of the cylinder block 61, and a space extending from a lower portion in the cylinder block 61 to the inside of the crankcase 65 is a crank chamber 66. An oil pan 67 is disposed at the lower end of the crankcase 65, and the crankshaft 11 is rotatably supported. In this case, spaces 60L and 60R are formed between the cylinder heads 63L and 63R and the cylinder head covers 64L and 64R, respectively.

  On the cylinder heads 63L, 63R, substantially semicircular arc bearings 63a, 63a,... That support the intake camshaft 21 and the exhaust camshaft 22 from the lower side at predetermined intervals in the axial direction of the crankshaft 11, respectively. Each of the bearing portions 63a includes a cam cap 23 having a substantially semicircular arc-shaped bearing portion 23a for individually supporting the intake camshaft 21 and the exhaust camshaft 22 from above, and a pair of bolts 24, 24 is fastened. The intake camshaft 21 and the exhaust camshaft 22 are rotatably supported by bearings 63a and 63R of the cylinder heads 63L and 63R and bearing portions 23a of the cam caps 23 via bearings. In this case, the chain case 3 is also attached to one side of the engine 6 (the front side in FIG. 3), and the chain case 3 has upper ends of the cylinder heads 63L and 63R and the cylinder head covers 64L and 64R. Are communicated with one side of the spaces 60L and 60R (hereinafter simply referred to as spaces), and the lower end portion communicates with the lower portion of the crankcase 65.

  The engine 1 is also provided with a PCV device 4. The separator case 42 of the oil separator 41 of the PCV device 4 is attached to the upper surface of the horizontal portion formed between the banks 62L and 62R on the cylinder block 61 by means such as bolting. In this case, the upstream end of the blow-by gas introduction hose 43 is open to the cylinder head cover 64L of one bank 62L (the left bank in FIG. 3), and blow-by gas blown into the crank chamber 66 is transferred to the cylinder heads 63L, 63R and the cylinder block 61 are extracted through a plurality of oil return holes penetrating in the vertical direction and introduced into the separator case 42.

  Further, the cylinder head cover 64R of the other bank 62R is provided with a fresh air inlet 71 as an inlet for introducing fresh air for ventilation in the engine 6. The fresh air introduced into the space 60R from the fresh air introduction port 71 circulates in the crank chamber 66 through the oil return holes and the chain case 3, and together with the blow-by gas from the upstream end of the blow-by gas introduction hose 43. The fresh air discharged and the blow-by gas is introduced into the surge tank through the separator case 42 and the blow-by gas discharge hose 45.

  Of the cam caps 23, the side of the cam case 23 on the side opposite to the chain case 3 (on the front side in FIG. 3) on the cylinder heads 63L and 63R is located in the spaces 60L and 60R. Are provided with weirs 72L and 72R protruding upward from the upper end surfaces of the cylinder heads 63L and 63R so as to block outflow of oil used for lubrication of the camshafts 21 and 22 to the chain case 3 side. Of these weirs 72L and 72R, the fresh air inlet 71 is introduced into the space 60R from the fresh air inlet 71 at the upper end of the weir 72R on the other bank 62R side provided in the cylinder head cover 64R. A throttle passage 73 for adjusting the flow rate of fresh air toward the chain case 3 is formed. The throttle passage 73 is formed between the inner surface of the cylinder head cover 64R and the upper end surface of the weir 72R.

  Accordingly, in the second embodiment, the fresh air introduced into the space 60R from the fresh air introduction port 71 of the cylinder head cover 64R of the other bank 62R is the cam cap 23 positioned closest to the chain case 3 in the space 60R. The flow rate to the chain case 3 side is adjusted by the throttle passage 73 at the upper end of the weir 72R that protrudes upward from the upper end surface of the cylinder head 63R on the side surface of the chain case 3. As a result, most of the flow of fresh air is not guided to the chain case 3 side and is tuned smoothly, and fresh air introduced into the space 60R from the fresh air inlet 71 of the cylinder head cover 64R It is sufficiently guided to the crank chamber 66 in the crankcase 65 through each oil return hole and the chain case 3, and fresh air from the fresh air introduction port 71 can flow uniformly into the engine 6.

  In the spaces 60L and 60R, most of the oil used for lubrication of the camshafts 21 and 22 is placed on the cylinder heads 63L and 63R on the side opposite to the chain case 3 of the cam cap 23 located closest to the chain case 3 side. The weirs 72L and 72R projecting upward from the end surface are reliably dammed without flowing into the chain case 3 side, and returned to the oil pan 67 through the oil return holes. The rotational friction of the timing chain 33 due to the oil can be reduced.

  Further, by providing the weirs 72L and 72R on the side opposite to the chain case 3 of the cam cap 23 located closest to the chain case 3 in the cylinder heads 63L and 63R, the weirs 72L and 72R are formed using the cam cap 23. As a result, the weirs 72L and 72R can be formed at a lower cost than in the case of newly forming.

  In addition, this invention is not limited to said each Example, The other various modifications are included. For example, in the second embodiment, the upstream end of the blow-by gas introduction hose 43 is opened to the cylinder head cover 64L of one bank 62L, and the fresh air inlet 71 is provided in the cylinder head cover 64R of the other bank 62R. The fresh air introduced from the introduction port 71 circulates in the crank chamber 66 through each oil return hole and the chain case 3 and is discharged together with the blowby gas from the upstream end of the blowby gas introduction hose 43. A fresh air inlet is opened to each cylinder head cover of the bank, and the upstream end of the blow-by gas inlet hose is opened to the crank chamber in the crankcase. The fresh air introduced from the fresh air inlet of each bank is blow-by gas It may be discharged together with the blow-by gas from the upstream end of the introduction hose. In this case, a throttle passage is formed at the upper end of the weirs of both banks.

  Further, in each of the above embodiments, the weirs 52, 72L, 72R are provided on the side opposite to the chain case 3 of the cam cap 23 located closest to the chain case 3, but are integrated with the cam cap located closest to the chain case. A weir may be provided. In this case, the weir can be installed simply by attaching the cam cap positioned closest to the chain case to the upper end surface of the cylinder head, and the number of assembling work steps can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal side view of a state in which a cylinder head cover and a chain case of an inline engine according to Embodiment 1 of the present invention are cut away. Similarly, it is a longitudinal front view of a state in which the engine is cut closer to the chain case than the cam cap located closest to the chain case. It is a vertical front view of the state which cut | disconnected the V-type engine which concerns on Example 2 of this invention near the chain case rather than the cam cap located in the most chain case side.

Explanation of symbols

1 Inline engine (engine)
10 Space 13 Cylinder head 14 Cylinder head cover 23 Cam cap 3 Chain case 51 Fresh air inlet (inlet)
52 Weir 53 Restricted passage 6 V-type engine (engine)
60 space 63L, 63R
Cylinder head 64L, 64R
Cylinder head cover 71 Fresh air inlet (inlet)
72L, 72R
Weir 73 Restricted passage

Claims (3)

In the cylinder head structure in which an inlet for introducing fresh air exhausted from the lower part of the engine that is provided for ventilation inside the engine opens into a space between the cylinder head and the cylinder head cover.
A chain case with an upper end communicating with the space is provided on one side of the engine.
At the chain case side end on the cylinder head is provided with a weir for blocking outflow of oil in the space to the chain case side,
A cylinder head structure, characterized in that a throttle passage for adjusting a flow rate of fresh air introduced into the space from the introduction port into the space is formed at an upper end portion of the weir. An inlet for introducing fresh air that is provided for ventilation inside the V-type engine and exhausted from the cylinder head of one bank of the V-type engine is provided with the cylinder head and the cylinder head cover of the other bank of the V-type engine. In the cylinder head structure that opens into the space between
One side of the V-type engine is provided with a chain case whose upper end communicates with the space between the cylinder head and the cylinder head cover of both banks.
At the chain case side ends on the cylinder heads of both banks, there are provided weirs for blocking outflow of oil in the space of both banks to the chain case side,
Among the weirs, the upper end of the other bank side weir is formed with a throttle passage for adjusting the flow rate of fresh air introduced from the introduction port into the space to the chain case side. A characteristic cylinder head structure. In the cylinder head structure according to claim 1 or 2,
A cylinder head structure characterized in that the weir is provided on a cam cap located closest to the chain case in the space between the cylinder head and the cylinder head cover.

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