Valve inserting apparatus for an internal combustion engine

A valve inserting apparatus for an internal combustion engine has a cylinder head of the engine supported by a jig such that its surface on a combustion chamber side is positioned facing upward and the longitudinal axis of a valve guide assembled to the cylinder head is kept vertical while a valve is inserted into the valve guide from above. The valve inserting apparatus includes a valve inserting unit for moving upwards and downwards. A valve holding device detachably, swingably, holds the valve with its head portion facing upward. A valve push-in device is provided and a suction device moves into contact with a lower end of the valve guide. The push-in device comprises an upwardly and downwardly movable push rod having a weight attached to the upper end portion. The push rod abuts the head portion of the valve from above. The valve inserting unit includes a first detector for detecting whether or not the push rod is at a position higher than a first predetermined reference position, such that the position of the push rod when the push rod in abutment with the valve and the valve inserting unit has been lowered to a predetermined position where the lower end of the valve has been inserted into an upper end of the valve guide to a predetermined depth. The valve inserting device further includes a second detector for detecting whether or not the push rod is at a position lower than a second predetermined reference position, that is, the position of the push rod when the lower end of the valve reaches the stem seal.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a valve inserting apparatus for inserting a valve 
into a valve guide assembled into a cylinder head of an internal 
combustion engine. 
2. Description of the Prior Art 
In a prior art apparatus disclosed in Japanese Patent Application 
Publication No. Sho 52-27866 a jig means supports a cylinder head in such 
a manner that its surface on a combustion chamber side is positioned 
facing up and a longitudinal axis of a valve guide is in a vertical 
position. A valve inserting unit, which can be driven to move up and down, 
is provided. The valve inserting unit includes a valve holding member 
which holds a valve with its head portion facing up and which allows the 
valve to be detachable and slightly swingable, and a push rod for abutting 
a head portion of the valve. A suction means moves in and out of contact 
with a lower end of the valve guide, such that when the suction means is 
brought into contact with the lower end of the valve guide, the inserting 
unit is lowered to a predetermined position and the lower end of the valve 
held by the holding member is drawn into and inserted into the upper end 
of the valve guide by a suction force of the suction means. The suction 
means is then separated from the valve guide and the holding means 
releases the valve so the valve can be pushed into the valve guide by the 
push rod. The push rod is arranged to be movable upwards and downwards by 
a pushing cylinder connected thereto. 
With this conventional type apparatus, when the lower end of the valve is 
interfered with by the upper end surface of the valve guide and is not 
drawn into the valve guide, the valve is pushed against the valve guide by 
the pushing of the valve by the pushing cylinder. Thus, there can often be 
damage to the upper end opening thereof. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to provide a valve inserting 
apparatus for inserting a valve into a valve guide assembled into a 
cylinder head of an internal combustion engine. 
It is another object of the present invention to provide a valve inserting 
apparatus which includes a first detecting device for detecting if the 
valve stem, because of misalignment, contacts the top of the valve guide 
such that the insertion of the valve is inhibited. 
It is still another object of the present invention to provide a valve 
inserting apparatus which includes a second detecting device for detecting 
if the valve stem passes through the bottom of the valve guide as a result 
of the lack of a stem seal thereon. 
The present invention is directed to a valve inserting apparatus for an 
internal combustion engine wherein a cylinder head of the engine is 
supported by a jig such that its surface on a combustion chamber side is 
positioned facing upward and the longitudinal axis of a valve guide 
assembled to the cylinder head is kept vertical while a valve is inserted 
into the valve guide from thereabove. The valve inserting apparatus 
comprising a valve inserting device for moving upwards and downwards; a 
valve holding device for detachably, swingably, holding the valve with its 
head portion facing upward; a valve push-in device; and a suction device 
for moving into contact with a lower end of the valve guide. The push-in 
device comprises an upwardly and downwardly movable push rod having a 
weight attached to the upper end portion thereof, the push rod abutting 
the head portion of the valve from above. The valve inserting device 
includes a first detecting device for detecting whether or not the push 
rod is at a position higher than a first predetermined reference position, 
such that the position of the push rod when the push rod in abutment with 
the valve and the valve inserting device has been lowered to a 
predetermined position where the lower end of the valve has been inserted 
into an upper end of the valve guide to a predetermined depth. The valve 
inserting device further includes a second detecting device for detecting 
whether or not the push rod is at a position lower than a second 
predetermined reference position that is the position of the push rod when 
the lower end of the valve reaches the stem seal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, a supporting column 2 is vertically provided on 
a machine base 1 so as to be movable forward and rearward by a driving 
source (not illustrated). A swingable frame 3 is supported on an outer 
circumference of an upper portion of the supporting column 2 so as to be 
swingable by a driving source (not illustrated), and a supporting arm 6 
which is movable upwards and downwards along a guide bar 5 by a cylinder 4 
is attached to the swingable frame 3. The supporting arm 6 is provided 
with a valve inserting unit 7 extending downward therefrom. 
The valve inserting unit 7 has a pair of upper and lower parallel 
supporting plates 9 and 10 arranged to be horizontally movable along the 
supporting arm 6 by a cylinder 8. The valve inserting unit 7 includes a 
valve holding means 7a and a valve push-in means 7b. 
As shown clearly in FIG. 3, the valve push-in means 7b comprises a push rod 
12 which is inserted through the lower supporting plate 10 and is movable 
upwards and downwards. A weight 11 is provided at the upper end of push 
rod 12. A push rod supporting member 14, which is movable upwards and 
downwards by a cylinder 13, is fixed to the upper supporting plate 9 and 
serves to support, at a horizontally extending portion 14a, a lower 
portion of the weight 11 of the push rod 12. A push rod pushing member 16, 
which is movable upwards and downwards by a cylinder 15, is fixed to the 
upper supporting plate 9 and uses its horizontally extending portion 16a 
to push the upper end portion of the push rod 12. 
The push down force of the push rod 12 caused by its own weight including 
the weight 11, is set to be less than the force needed for causing the 
lower end of a valve V to thrust through a stem seal S attached to a lower 
end of a valve guide G. Thus, the lower end of the valve V passes through 
the stem seal S as a result of the pushing force of the push rod 12 and 
the weight 11 plus the pushing force of the pushing member 16. 
The holding means 7a comprises a guide member 18 which is moved by a 
cylinder 17 in the horizontal direction in relation to the supporting 
plate 10. The guide member 18 is provided at its end surface with a guide 
groove 18a which is slightly larger than the diameter of the shaft portion 
of the valve V, as shown in FIGS. 11 and 12. A closure member 22 is fixed 
to an end portion of a lever 21 and is rotatable about a supporting shaft 
19 by the operation of a cylinder 20. The closure member 22 opens and 
closes the guide groove 18a of the guide member 18. Valve head supporting 
members 18b for supporting the head portion of the valve V at two points 
on the circumference of a tapered surface thereof, project from an upper 
surface of the guide member 18, so that the valve V can be swung with 
respect to the supporting members 18b to the extent of the free space 
within the guide groove 18a. 
The above described embodiment is a valve inserting apparatus for a 
multi-cylinder engine, in which there are plural pairs of guide members 18 
and closure members 22 forming the valve holding means 7a, and a plurality 
of the push rods 12 forming the valve push-in means 7b. 
A jig means 23 is located in front of the machine base 1. The jig means 23, 
as shown clearly in FIGS. 2 and 5, comprises a jig plate 26 for supporting 
a cylinder head W, with its surface on a combustion chamber side facing 
upward. The jig plate 26 is pivotally supported on a jig base 25 mounted 
on a supporting base 24 such that the jig plate 26 is swingable about 
horizontal shaft 27. 
A lever 28 and a nearly V-shaped stopper member 29 are fixed to an end 
portion of the horizontal shaft 27, and a cylinder 30 on the supporting 
base 24, is connected to one end of the lever 28 such that the jig plate 
26 may be swung by the cylinder 30. A stopper pin 31, which is arranged to 
abut the other end of the lever 28 for positioning the jig plate 26 in its 
horizontal position, is provided on the jig base 25 and is retractable by 
a cylinder 31a to a withdrawn position for allowing a swing movement of 
the jig plate 26. Additionally, a pair of stopper pins 32 and 32' are 
mounted on jig base 25 to abut the corresponding ends of the stopper 
member 29 for regulating the swinging movement of the jig plate 26. Thus, 
at the position where the swing movement in one direction thereof is 
regulated by the stopper pin 32 on one side, the longitudinal axis of the 
valve guide G on the intake side of the cylinder head W is vertical, and 
at the position where the swing movement in the other direction thereof is 
regulated by the stopper 32' on the other side, the longitudinal axis of 
the valve guide G' on the exhaust side is vertical. A positioning pin 26a 
for the cylinder head W is provided on the jig plate 26. 
A pair of tubular suction means 33 and 33' connected to a negative pressure 
source (not illustrated), are positioned on the supporting base 24 coaxial 
with the longitudinal axes of the respective valve guides G and G, when 
the jig plate 26 is in its respective swung position in one direction or 
the other, so that, by moving the respective suction means 33 and 33' 
upwards and downwards by the respective cylinders 34 and 34' , the suction 
means are brought into contact with and separated from the lower ends of 
the respective valve guides G and G'. 
Valve supply means 35 and 35' for intake valves and exhaust valves are 
disposed on both sides of the machine base 1, and each of the supply means 
35 and 35' comprises, as shown in FIGS. 6 and 7, plural holding tubes 36 
mounted on supporting base 37 for detachably holding the valve V with its 
head portion facing up. Oil containing tanks 38 on the supporting base 37 
surround the respective holding tubes 36, whereby oil is applied to the 
shaft or stem of each valve V. 
Besides the valve holding means 7a and the valve pushin means 7b, the valve 
inserting unit 7 is provided with a first detecting means 39 and a second 
detecting means 40. The first detecting means 39 detects whether or not 
the push rod 12 is at a position above a first reference position, that 
is, a lowered position of the push rod 12 (the position of the push rod on 
the left side in FIG. 16) when the push rod 12 is brought into contact 
with the valve V and the unit 7 has been lowered to a predetermined 
position where the lower end of the valve V is inserted into the upper end 
of the valve guides G or G, to a predetermined depth. The second detecting 
means 40 detects whether or not the push rod 12 is at a position lower 
than a second reference position, that is, a lowered position of the push 
rod 12 (the position of the push rod on the right side in FIG. 17) when 
the lower end of the valve V reaches the stem S on the lower end of the 
valve guide G or G'. 
The respective detecting means 39 and 40 comprise light projecting means 
39a and 40a and light receiving means 39b and 40b which are positioned on 
opposite sides of the push rods 12 facing each other. The light projecting 
and receiving means 39a and 39b of the first detecting means 39 are 
positioned at a height such that when the push rod 12 is at a position 
higher than the first reference position, the light from the light 
projecting means 39a is obstructed by an upper end of the push rod 12. The 
light projecting and receiving means 40a and 40b of the second detecting 
means 40 are positioned at a height such that when the push rod 12 is at a 
position lower than the second reference position, the light from the 
light projecting means 40a is obstructed by the weight 11 of the push rod 
12. 
The operation of the foregoing embodiment will be explained as follows: 
First, the swing movement of the swingable frame 2 moves the valve 
inserting unit 7 from the condition shown in FIG. 1, to a position above 
the intake valve supply means 35, where it is lowered by the cylinder 4. 
Then, by operation of the cylinder 17 and the cylinder 20 of the valve 
holding means 7a, the guide member 18 and the closure member 22 which were 
previously opened, are closed, whereby the intake valve V held by each of 
the holding tubes 36 of the supply means 35 is held by unit 7. The unit 7 
is then raised and is moved to a position above the jig means 23 by the 
swing movement of the swingable frame 3 and the movement of the supporting 
column 2. When this occurs, the jig plate 26 has already been swung from 
its horizontal position to its swung position on one side where one end of 
the stopper member 29 comes in contact with the stopper pin 32. The 
suction means 33 is elevated so that, as shown in FIG. 8, the suction 
means 33 is in contact with the stem seal S at the lower end of the valve 
guide G on the intake side, thus enabling a suction operation of the 
suction means 33 by the negative pressure source which is started at the 
same time as the downward movement of the unit 7 by the cylinder 4. 
Thus, the intake valve V which is swingably held by the valve holding means 
7a is compensated for misalignment in its centering displacement by the 
suction operation of the suction means 33, and, as shown in FIG. 9, the 
lower end thereof is drawn into an upper end opening of the valve guide G 
and the valve inserting unit 7 is stopped after being lowered to a 
predetermined position. Thereafter, the push rod supporting member 14 is 
lowered by the cylinder 13 to a position where the push rod 12 abuts the 
head portion of the intake valve V, as shown in FIG. 13. In this 
condition, the detecting operation of the first detecting means 39 is 
carried out. 
If at this stage, there is a misoperation in suction into the guide G 
because the lower end of the valve V contacts the upper end of the valve 
guide G as in the case of the intake valve V shown on the right side in 
FIG. 16, the push rod 12 abutting thereon is stopped from moving further 
downwards at a position higher than the first reference position. The 
light from the light projecting means 39a of the first detecting means 39 
is thus, obstructed by the upper end of the push rod 12 and is not 
received by the light receiving means 39b. In such a case, the valve 
inserting unit 7 is raised and then lowered again for reinsertion of the 
valve V. 
When all the intake valves V are drawn into the valve guide G, all the push 
rods 12 are lowered to the first reference positions thereof, and a light 
receiving signal is thus generated from the light receiving means 39b, the 
holding of the valve by the valve holding means 7a is released, the 
suction means 33 is lowered, and the push rod supporting member 14 is 
lowered to a predetermined lower end position. 
With the operation described above, the push rod 12 is caused to move 
downward by its own weight, pushing the intake valve V into the valve 
guide G, and when the lower end of the intake valve V reaches the stem 
seal S, the resilient force of the stem seal acts to stop the intake valve 
V from moving down any further. In this condition, the detecting operation 
by the second detecting means 40 is carried out. 
If, the stem seal S does not exist at the lower end as in the case of the 
guide valve G shown on the left side in FIG. 17, the lower end of the 
intake valve V moves downwards and projects through the guide G. The push 
rod 12 which is in abutment thereon is lowered to a position lower than 
the second reference position, and the light from the light projecting 
means 40a of the second detecting means 40 is obstructed by the weight 11 
of the push rod 12 so as not to be received by the light receiving means 
40b. In this case, the valve inserting unit 7 is elevated, and the fact 
that the stem seal S does not exist is indicated to an operator by a 
warning means (not illustrated) such as a buzzer or the like. 
When all of the valve guides G are provided with the stem seals S attached 
thereto, all the push rods 12 are stopped at the second reference 
position, and a light receiving signal is generated from the light 
receiving means 40b. The push rod pushing member 16 is then lowered by the 
cylinder 15 to forcibly push down the push rod 12. With the operations 
above, the lower end of the intake valve V is lowered to project through 
the stem seal S while spreading it out, and the intake valve V is thus, 
inserted completely into the valve guide G. 
Next, the push rod 12 is returned to the original position by raising the 
pushing member 16 and the supporting member 14. The unit 7 is then 
elevated. By a retracting movement of the supporting column 2 and a swing 
movement of the swingable frame 3, the unit 7 is moved to a position above 
the valve supply means 35' for the exhaust valves, and at this position, 
the unit 7 is lowered and the exhaust valve is held by the holding means 
7a. Thereafter, the unit 7 is returned to the position above the jig means 
23, and during this time, the jig plate 26 is swung to a swung position 
thereof on the side in abutment on the stopper pin 32' . Thus, the 
longitudinal axis of the valve guide G' on the exhaust side is made 
vertical, and the insertion of the exhaust valve G' is carried out in 
almost the same manner as described above. 
Thus, according to the present invention, when there is a suction error in 
drawing the valve into the valve guide, it is possible to repeat the valve 
inserting operation through detection of the suction error without pushing 
the valve into the valve guide. Thus, the valve can be inserted properly 
without applying an unreasonable force. 
The present invention may be embodied in other specific forms without 
departing from the spirit or essential characteristics thereof. The 
presently disclosed embodiments are therefore to be considered in all 
respects as illustrative and not restrictive, the scope of the invention 
being indicated by the appended claims, rather than the foregoing 
description, and all changes which come within the meaning and range of 
equivalency of the claims are, therefore, to be embraced therein.