METHOD FOR PRODUCING WATER JACKET SPACER
A spacer (1) is injection molded by using an injection molding die having resin flow channels that are designed such that a plurality of gates (6) are arranged along the longitudinal direction at a position corresponding to the outer peripheral surface of a side wall part (4) in which a plurality of arc-like peripheral surface parts (2) are connected through a waist part (3). After opening the mold and ejecting the spacer, the spacer is cooled with a runner (7) being connected to the gate (6), and thereafter, the runner (7) is cut off. As a result, when producing a water jacket spacer that is assembled to the inside of the water jacket and controls the flow of cooling water by injection molding, while producing with a high productivity without being affected by design constraints caused by draft angle, deformation in the post-molding cooling step is prevented.
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The present invention relates to a method for producing a water jacket spacer that is assembled into the inside of a water jacket provided in a water-cooled internal combustion engine.
BACKGROUND ARTIn a water-cooled internal combustion engine such as a water-cooled engine for automobiles, a water jacket serving as a cooling water-circulating channel is formed around a bore wall of a cylinder bore. Normally, by inserting and assembling a spacer (water jacket spacer) into the inside of such a water jacket, flow of cooling water is controlled.
Such a water jacket spacer is generally produced by injection molding by using a prescribed resin material. Patent Document 1 proposes a method in which, in order to prevent deformation of a water jacket spacer in a post-molding cooling step without using a jig for correcting the shape, the opposing parts of the cylindrical main body of the spacer to be inserted into a water jacket are connected by a connecting bride, the shape of the spacer is retained after molding, and then the connecting bridge is cut off.
RELATED ART DOCUMENT Patent Document
- Patent Document 1: JP-A-2005-105878
However, in the method of Patent Document 1, a runner for introducing a molten resin into a gate is used as the connecting bridge. As for the mold structure in this case, as shown in
By doing so, on the inner peripheral surface of the spacer 100, taking mold opening into consideration, it is required to provide draft angle in which inclination direction is different in the opposite sides of the parting line PL along a mold opening direction shown by an arrow in the figure. Therefore, as shown in
Further, generally, in order to keep the bore wall warm, as for the gap between the wall surface of the water jacket and the spacer, in many cases, a gap formed on the inner peripheral side of the spacer when assembled into the water jacket is designed to be narrower than a gap formed on the outer peripheral side of the spacer. Therefore, in the method of Patent Document 1, a problem arises that severe management is required to be conducted for burrs that remain on the inner surface of the spacer main body after gate cutting or for burrs that are formed along the parting line.
Further, when the connecting bridge that connects the opposing parts of the spacer main body is cut, tools for this cutting have to be inserted into the inside of the spacer main body, and as a result, handling of the tools has to be contrived in order that the tools do not interfere with the spacer main body.
The present invention has been made taking the above circumferences into consideration, and is aimed at providing a method for producing a water jacket spacer in which, when producing by injection molding a water jacket spacer that is assembled into the inside of a water jacket and controls the flow of cooling water while producing with a high productivity without being affected by design constraints caused by draft angle, deformation in the post-molding cooling step can be prevented.
Means for Solving the ProblemsThe method for producing a water jacket spacer according to the present invention is a method for producing a water jacket spacer that is assembled into the inside of a water jacket provided in a water-cooled internal combustion engine in order to control the flow of cooling water, wherein the water jacket spacer has a side wall part in which a plurality of arc-like peripheral surface parts are connected through a waist part;
a prescribed resin material is injection molded by using a molding die for injection molding in which resin flow channels are designed so that a plurality of gates are arranged along the longitudinal direction at a position corresponding to the outer peripheral surface of the side wall part; and after mold opening and ejecting, cooling is done while leaving a runner being connected to the gates, and thereafter, the runner is cut off.
Advantageous Effects of the InventionAccording to the present invention, when producing a water jacket spacer by injection molding, while producing the water jacket spacer with a high productivity without being affected by design constraints caused by draft angle, deformation of the water jacket spacer in the post-molding cooling step can be prevented.
Hereinbelow, an explanation will be made on the embodiment of the method for producing a water jacket spacer according to the present invention with reference to the drawings.
As shown in
In the cylinder block CBL, the bore walls BW of a plurality (four in the shown example) of cylinder bores CB are formed such that they are connected to each other in a constricted manner between the adjacent cylinder bores CB to form an integral body, and, in the periphery of such bore wall BW, a water jacket WJ as the circulating channel for cooling water is formed.
The spacer 1 has a shape that can be inserted into the inside of the water jacket WJ, and is formed such that it can extend along the bore wall BW having a constricted shape between the adjacent cylinder bores CB. Although, normally, the spacer 1 has a shape in which a plurality (four in the shown example) of cylindrical parts are integrally connected through waists part having the similar constricted shape in a hollow shape, the specific shape thereof is not particularly restricted. The spacer 1 can be appropriately designed such that, by assembling by insertion into the inside of the water jacket WJ, the spacer 1 controls the flow of cooling water that flows inside the water jacket WJ, whereby the temperature distribution of the bore wall BW can be optimized. For example, in addition to the shape insertable along the entire circumference of the water jacket WJ, it can have a shape that it is partially insertable into the inside of the water jacket WJ.
The schematic shape of the spacer 1 produced in the present embodiment is shown in
Then, after opening the injection molding die and ejecting the molded spacer 1, the spacer is cooled while leaving the runners 7 that are continued to the gate 6 in the shape of the teeth of a comb. Thereafter, the runner 7 is cut off.
By doing so, the runner 7 connected to the outer peripheral surface of the side wall 4 of the spacer 1 in the shape of the teeth of a comb suppresses deformation of the spacer 1 in a softened state immediately after the ejection, whereby the shape of the spacer 1 during a period for which the spacer 1 is cooled and solidified can be retained. The runner 7 that is connected to the side wall part 4 of the spacer 1 in the shape of the teeth of a comb is cut off after the spacer 1 is fully solidified and there is no fear of deformation.
As mentioned above, in the present embodiment, by using the runner 7 that is formed in the resin flow channel at the time of injection molding, the shape of the spacer 1 after the molding is retained. Since the gate 6 is arranged at a position corresponding to the outer peripheral surface of the side wall part, as shown in
Therefore, when the spacer 1 is assembled into the water jacket WJ, as shown in
Further, since burrs remaining in the spacer 1 after cutting the gate and burrs that are formed along the parting line PL are not formed on the inner peripheral surface side of the spacer 1, control thereof becomes facilitated.
Further, since gate cutting is conducted on the outer peripheral surface side of the spacer 1, handling of tools used therefor is facilitated.
As mentioned above, according to the present embodiment, when producing the spacer 1 by injection molding, while producing the spacer 1 with a high productivity without being affected by design constraints caused by draft angle, deformation of the spacer 1 in the post-molding cooling step can be prevented.
Another example of the spacer 1 produced in the present embodiment is shown in
Further, in the examples shown in
In the examples shown in
In the present embodiment, no restrictions are imposed on a resin material. Polypropylene, polyamide, polyphenylsulfone or the like can be given, for example. A resin material that is excellent in heat resistance, moisture resistance, anti-freezer resistance, wear resistance or the like can be appropriately selected.
As mentioned above, the spacer 1 can have a shape that is partially insertable into the inside of the water jacket WJ. For example, when the spacer 1 is assembled to a part of the side from which cooling water is flown to the water jacket WJ and the spacer 1 is not assembled to the side from which the cooling water is discharged from the water jacket WJ, if the spacer 1 has a shape having the side wall part 4 in which a plurality of the arc-like peripheral surface parts 2 are connected through the waist part 3 (see
Hereinabove, the present invention has been explained with reference to the preferable embodiment. However, the present invention is not restricted to the above-mentioned preferable embodiment, and it is needless to say that various modifications are possible within the scope of the present invention.
For example, in the above-mentioned embodiment, an explanation was made taking as an example a water jacket spacer used in a water-cooled inline-four engine for an automobile. The present invention can be applied to an inline multi-cylinder engine such as an inline-three engine. In addition, not only the inline engine, the present invention can be applied to a V-shaped engine and a horizontally-opposed engine. That is, the present invention can be widely applied to a water-cooled internal combustion engine provided with a water jacket.
Modification ExampleThe modification example of the present invention will be explained with reference to
When arranging a gate at a position corresponding to the waist part 3, as shown in
Further,
In the examples shown in
Further, when the spacer 1 is allowed to have a shape that is partially insertable into the inside of the water jacket WJ, by applying the present invention as in the case of the examples shown in
As in the case of the divided molded products 1a shown in
Accordingly, also by this embodiment, constraints caused by draft angle when designing the spacer 1 such that the temperature distribution of the bore wall BW can be optimized can be relaxed, and since burrs remaining in the spacer 1 after gate cutting and burrs that are formed along the parting line are also not formed on the inner peripheral surface side of the spacer 1, control thereof becomes facilitated. Further, when a gate cutting treatment is conducted, handling of tools used therefor is facilitated.
The documents described in the specification and Japanese application specification claiming priority under the Paris Convention are incorporated herein by reference in its entirety.
EXPLANATION OF REFERENTIAL NUMERALS
- 1. Spacer
- 1a. Divided molded products
- 2. Arc-like peripheral surface part
- 3. Waist part
- 4. Side wall part
- 5. Arc-like end surface part
- 6. Gate
- 7. Runner
- 7a. Reinforcing part
- WJ. Water jacket
Claims
1. A method for producing a water jacket spacer that is assembled into the inside of a water jacket provided in a water-cooled internal combustion engine in order to control the flow of cooling water, wherein
- the water jacket spacer has a shape having a side wall part in which a plurality of arc-like peripheral surface parts are connected through a waist part;
- a prescribed resin material is injection molded by using a molding die for injection molding in which resin flow channels are designed so that a plurality of gates are arranged along the longitudinal direction at a position corresponding to both ends in the direction orthogonal to the longitudinal direction of the water jacket spacer, but any gates are not arranged at a position corresponding to an inner peripheral surface of the side wall part being a surface facing a bore wall of the water-cooled internal combustion engine when the water jacket spacer is assembled into the inside of a water jacket,
- whereby there is no need to provide draft angle on the inner peripheral surface of the side wall part and it is possible to be opposed to the bore wall along an inclination thereof when the water jacket spacer is assembled into the inside of the water jacket,
- after mold opening and ejecting, cooling is done while leaving a runner being connected to the gates in a shape of a teeth of a comb, and thereafter, the runner is cut off.
Type: Application
Filed: Nov 15, 2019
Publication Date: Mar 12, 2020
Applicant: NICHIAS CORPORATION (Tokyo)
Inventors: Yoshifumi FUJITA (Tokyo), Shota UCHIDA (Tokyo), Kenichi NAKAMURA (Tokyo)
Application Number: 16/684,657