JPH03189481A - Bellows shaft seal mechanism for wax type thermostat and manufacture of bellows - Google Patents

Abstract

PURPOSE:To prevent cooling liquid and foreign material from entering inside by connecting a push rod and a guide member expandably and airtightly by a bellows. CONSTITUTION:The tip of a push rod 8 is airtightly engaged with the inside of the apex 13 of a bellows 12 as well as a guide member 6 is airtightly engaged with the inside of a skirt part 14. A main valve 4 is inserted together with the bellows 12 though the bellows 12 and fixed at the guide member 6 by a snap ring 15. Accordingly, the invasion of foreign material and liquid can be completely impeded being protected by the bellows 12, so that the overcooling and overheating of an engine can be dissolved and thereby the life of a thermostat is prolonged. The bellows 12 is manufactured by separately fixing numerous single cavity unit molds, for manufacturing a bellows provided at its body part with plural ring ribs 18 corresponding to the number of steps of the bellows, to the upper and lower templates of a molding machine and injecting raw material between the molds under high temperature and high pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is to determine the temperature of a coolant in an automobile engine.

Examples of the present invention will be described below.

1 and 2 are cross-sectional views of the wax type thermostat of the present invention, the former showing the main valve when it is fully open and the latter showing the main valve when it is closed. Generally, a wax type thermostat has a frame 3 fixed to a housing 2 that forms a valve seat 1, a main valve 4 that engages with the valve seat 1, and a guide member of a thermo-actuator 5 that press-fits and fixes the main valve, as shown in Fig. 1. 6 and a return spring 7 that engages between the main valve 4 and the frame 3.

The thermo-actuator 5 is constructed by integrating a bushing rod 8, a guide member 6 that engages with the bushing rod 8, and an elastic seal spool 9, and inserting and pressing the bushing rod into a heat-sensitive tube 11 filled with wax 10.

Numeral 12 is a bellows which airtightly engages the tip of the push rod 8 of the thermo-actuator 5 inside the apex 13 of the bellows 12 and the kite member 6 inside the skirt portion 14 of the bellows 12. are inserted into the guide member 6 together through the bellows 12 and fixed to the guide member 6 with a retaining ring 15.

When the temperature of the engine coolant rises, the thermosensitive cylinder 1! The elastic seal spool 9 is deformed by the melting and expansion of the wax 10 inside, and the push rod 8 is squeezed upward. However, since the push rod 8 is engaged with and supported by the apex 16 of the housing 2 via the bellows 12, the main valve 4 is relatively opened downward (FIG. 1).

Also, when the water temperature drops, the molten wax inside the thermosensitive cylinder
Since O solidifies and contracts, the main valve 4 is closed by the return spring 7 (FIG. 2). In this way, the guide member 6 of the thermo-actuator 5 slides up and down with respect to the push rod 8 which is engaged and supported by the apex 16 of the housing 2. The main valve 4 fixed thereto opens and closes accordingly.

Figures 3 and 4 are cross-sectional views of a conventional wax-type thermostat. From the closed state (Figure 3) where moisture has already entered the elastic seal spool 9, the lateral pressure exerted by the molten wax IO causes the elastic seal to open. Spool 9 is push rod 8
The liquid reaches the fully open lift confined at the tip of the push rod 8 (Fig. 4). A diagram of the temperature of the coolant versus valve lift in this case is shown in curve B (dotted line) in FIG. Curve A (solid line) is the measured value in the case of the present invention (FIGS. 1 and 2) in which there is no liquid in the elastic seal spool 9.

In the case of curve B, the valve opening temperature is low, and when the valve is closed, the valve does not seal and opens slightly due to the presence of liquid. This will cause overcooling, which will reduce the thermal efficiency of the engine and increase the generation of harmful waste gases. Furthermore, the presence of this liquid causes the lift to rise excessively, causing the thermo-actuator to go flat, causing wax to leak and the valve to close, causing overheating and causing serious engine trouble.

In the present invention, since the bellows protects the thermostat and completely prevents liquid and foreign matter from entering, overcooling and overheating of the engine are eliminated, and the life of the wax type thermostat is greatly extended.

FIG. 6 shows a single-cavity unit mold for manufacturing bellows, FIG. 7 shows its female mold, and FIG. 8 shows its male mold.

These single molds for forming bellows are separated into male and female parts and fixed in large numbers to the upper and lower mold plates of a molding machine, and raw materials are injected between the molds under high temperature and pressure to mass-produce products at once. be.

FIG. 9 shows a cross-sectional view of the product.

Its apex 13 engages with the tip of the push rod 8, its skirt part 14 engages with the guide member 6, and its body part 17 is slidable on the push rod 8 and corresponds to the full opening lift of the main valve 4. The body portion 17 is provided with a plurality of ring-shaped ribs 18 corresponding to the number of stages of the bellows.

When this is attached to the thermostat, it is pressurized by the return spring 7, and while the inner diameter of the thick ring-shaped rib remains the same, the thin middle part with relatively weak resistance swells, forming a bellows very easily and automatically. Yes (Figure 2).

Moreover, since each valley of the bellows is protected and reinforced by ribs, its expansion and contraction life is outstanding.

As described above, the bellows manufacturing method of the present invention is made up of a body part including the apex part and a skirt part, and the length of the body part is sufficient to provide the required number of ring-shaped ribs, making it extremely easy to manufacture the mold. A large number of bellows can be molded and a low cost bellows can be obtained.

This bellows manufacturing method can be utilized not only for the wax-type thermostat of the present invention but also for the low-cost manufacturing of various seal bellows for air cylinders, hydraulic cylinders, and others.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the wax type thermostat of the present invention when the valve is fully open, Fig. 2 is a sectional view of the wax type thermostat of the present invention when the valve is closed, and Figs. The latter shows the state when fully opened, Fig. 5 is a diagram of the valve opening temperature versus valve lift, Fig. 6 shows a single unit mold for producing bellows, Fig. 7 shows its female mold, and Fig. 8 shows its It is a male type, and FIG. 9 shows a cross-sectional view of the product. 4...Main valve 5...Thermo actuator 6...Guide member 7...Return spring 8...Push rod 9...Elastic seal spool 0...Wax l...・Thermal cylinder 2 ... Bellows 3 ... Vertex 4 of bellows ... Skirt part 5 of bellows ... Retaining ring 8 ... Rib of bellows

Claims (1)

[Claims] 1. A guide member that is slidably engaged with a push rod and an elastic seal spool that is engaged with the guide member and also slidable on the push rod are integrated, In a wax-type thermostat equipped with a thermo-actuator that is inserted and crimped into a heat-sensitive tube filled with wax, the top of the bellows is fixed to the tip of the push rod, and the skirt of the bellows is fixed to the guide member. ,
A bellows of a wax type thermostat, characterized in that the sliding parts of the push rod and guide member are held airtight by a telescopic bellows, completely preventing coolant and foreign matter from entering the thermoactuator. Shaft seal mechanism. 2. Airtightly engage the tip of the push rod of the thermo-actuator with the inner apex of the elastic seal bellows, and the guide member with the inner side of the skirt of the bellows, and guide the main valve together through the bellows. A method for attaching a bellows shaft seal to a wax type thermostat as claimed in claim 1, characterized in that the bellows shaft seal is inserted into the member and fixed to the guide member with a retaining ring. 3. Its apex is engaged with the tip of the push rod, its skirt part is engaged with the guide member, and its body part is slidable on the push rod and has a length corresponding to the full opening lift of the main valve. A large number of single-cavity unit molds for manufacturing bellows, each having a plurality of ring-shaped ribs on the body corresponding to the number of stages of the bellows, are separately fixed on the upper and lower mold plates of a molding machine, and the raw materials are heated under high temperature and high pressure. A manufacturing method for shaft-sealing bellows that is injected between molds and mass-produced at once.