EP3717759A2

EP3717759A2 - A thermostat housing with improved flow geometry reducing pressure drop

Info

Publication number: EP3717759A2
Application number: EP18913273.1A
Authority: EP
Inventors: Hikmet KANBUR
Original assignee: Kirpart Otomotiv Parcalari Sanayi ve Ticaret AS
Current assignee: Kirpart Otomotiv Parcalari Sanayi ve Ticaret AS
Priority date: 2017-11-30
Filing date: 2018-11-15
Publication date: 2020-10-07
Also published as: EP3717759A4; WO2019194765A3; WO2019194765A2; TR201719196A2

Abstract

This invention relates to a thermostat housing (10) which prevents the vortex (23) formation at the dead points (22) due to pressure difference between coolant portions within the conventional housing and thus provides improvement in the pressure drop occurred during the coolant streaming through the housing. The improvement is obtained by changing both the entrance (20) geometry and elbow (30) geometry of the thermostat housing (10).

Description

DETAILED DESCRIPTION OF THE INVENTION

A THERMOSTAT HOUSING WITH IMPROVED FLOW GEOMETRY REDUCING PRESSURE

DROP

Technical Field

The invention relates to a thermostat housing structure with improved flow geometry reducing pressure drop.

More specifically, the invention relates to an improved thermostat housing which prevents the vortex formation at the dead points of sharp corners during coolant streaming through the housing, thus provides improvement in coolant pressure drop occurred through the thermostat assembly thereof.

Prior Art

In the all closed circulation systems, preserving pressure is a crucial issue for continuing of the fluid within the closed system to flow. Especially, where the fluid has to change direction to flow, big pressure lost is occurred during the direction change of fluid.

The coolant flowing through the engine cooling system has to change direction up to 90 degrees when the coolant passes through thermostat housing of thermostat assembly. The direction change of the coolant causes the formation of vortex at both the sharp corners and the dead points of thermostat housing. Consequently, the situation results in the significant pressure drop in the pressure of the coolant flowing through the thermostat housing. These pressure drops in the engine coolant pressure cause inefficiency in the engine cooling system.

The document W02016100670 mentions a thermostat housing for engine cooling system and more particularly a thermostat valve configuration used within the thermostat housing. The valve configuration provides turbulence and pressure drop occurred across the thermostat housing to decrease. However, here, there is not any improvement about the thermostat housing geometry which is the biggest reason of the fluctuation formation and the pressure drop occurred across the thermostat housing in art.

The document 8967091 mentions a thermostat housing including least two thermal elements within its housing member. Since these thermo-actuators have staggered opening temperature values, they provide optimized coolant flow through the engine cooling system. Although the thermostat assembly reduces abrupt transitions in radiator coolant flow, consequently the fluctuations, the innovation does not relate to the improvement in sharp thermostat housing geometry which is the biggest reason of the fluctuations and the pressure drop occurred within conventional thermostat housing.

The document EP2954179 also focused to solve the turbulence problem and the pressure drop problem occurred across the thermostat housing. Here, the turbulence problem and the pressure drop problem are solved by a thermostat assembly with rotary valve system. Instead of the conventional thermostat assembly, in the invention, a circular thermo-actuator is used to provide the rotary valve system. Although the document also provides a solution for the turbulence problem and the pressure drop problem occurred across thermostat housing, the solution does not relate to the improvement in sharp thermostat housing geometry which is the biggest reason of the fluctuations and the pressure drop occurred within conventional thermostat housing.

As a result, there is any document focused on reducing the pressure drop occurred due to both the sharp corners and the dead points within the thermostat housing. So, the solution of the present invention is required.

Objectives and Short Description of the Invention

The aim of the present invention is to present a thermostat housing providing improvement in the pressure drop of the coolant passing through thereof by changing geometry of both the entrance and the corner within the thermostat housing, thus to reduce the pressure drop raised from sharp thermostat housing geometry in art.

Another aim of the present invention is to prevent the vortexes formed due to pressure different between the coolant portion at dead points formed in housing corners and the coolant potion which continues to flow with high rate through the housing, thus to reduce the pressure drop raised from the vortexes.

Description of the Figures

Figure 1 a shows a cross-sectional view of the present thermostat housing having soft geometrical transition at the corners.

In figure 1 b, the representative top sectional view of the present thermostat housing entrance which is ever-expanding towards the inner space of the housing is given.

In figure 1c, a representative cross-sectional view of the present elbow structure of the thermostat housing is given. The entrance and the elbow structure of the present thermostat housing have softer geometrical transition than the sharp transitions of the conventional thermostat housing. Figure 1d shows the top sectional view of the entrance and the elbow structures of the present thermostat housing together.

In figure 2a, a cross-sectional view of the conventional thermostat housing having sharper geometrical transition at corners is given.

Figure 2b shows a top sectional view of the entrance and the elbow structures of the conventional thermostat housing together.

In figure 2c, the representative top sectional view of the conventional thermostat entrance having sharp transitions at its entrance corners is given. The sharp geometrical transition results in the dead point formation at these entrance corners. Since the coolant pressure in these dead points is nearly zero, the pressure difference between the coolant portion at these dead points and the coolant portion in the coolant flow stream causes vortex formation thereof, consequently the efficiency of the engine cooling system to decrease.

Figure 3 and figure 4 show the coolant pressure distribution across the present thermostat housing.

Figure 5 and figure 6 show the coolant pressure distribution across the conventional thermostat housing.

Reference Numerals

10. Thermostat housing

11. Housing inner space

20. Entrance

21. Entrance corner

22. Dead point

23. Vortex

30. Elbow

V1. Pre-expansion average speed, m/sn

V2. Post-expansion average speed, m/sn

D1. Hose pre-expansion inner-diameter

D2. Hose post-expansion inner-diameter

r: Curve diameter

d: Inner tube diameter

Q: Curve angle Detailed Description of the Invention

This invention relates to a thermostat housing (10) which, having soft transition geometry at both its entrance (20) and elbow (30) portions, prevents the dead points (22) formation and the huge pressure difference between the coolant portions within the housing and thus provides the engine coolant to flow through thereof with improved pressure drop, consequently the efficiency of the engine cooling systems to increase.

For a better understanding of the present invention, it is better to explain it with using the figures 1 , figure 2 and related equations. In the figure 2a, a cross-sectional view of the conventional thermostat housing is given. A top sectional view of the conventional thermostat housing taken from the section B shown in figure 2a is given in figure 2b. This figure shows the entrance (20) and the elbow (30) structure’s sectional geometries of the conventional thermostat housing. The both the entrance (20) and the elbow (30) portion of the conventional thermostat assembly have sharp transition geometries which cause the pressure drop within the coolant. Also, the dead points (22) are formed in the entrance corners (21) of the conventional thermostat assemblies. Due to the inertia of the coolant at these entrance corners (21), the pressure of this region is nearly zero. However, the pressure of the coolant which continues to flow through the thermostat housing is very high. The pressure difference between the coolant portions within the housing causes the formation of vortex (23) between thereof. The vortexes (23) within the housing also causes pressure drop of the engine coolant passing through the thermostat housing. In figure 2c, the vortexes (23) which are formed in the entrance corner (21) of the conventional thermostat housing are shown.

As seen in figure 1a, a cross-sectional view of the present thermostat housing (10) having softer geometric transition at both its entrance (20) and its elbow (30) is shown. Also, a top sectional view of the present thermostat housing (10) taken from the section A shown in figure 1 a is given in figure 1d. The present invention provides pressure drop improvement in two different forms of the thermostat housing (10) respect to the conventional thermostat housing. One of these improvements is about the entrance (20) form and a representative top sectional view of the present entrance (20) form is shown in figure 1 b. As shown in figure 1 b, the vortexes (23) and the pressure drops occurred due to the sharp geometrical transition from the entrance (20) outlet to the housing inner space (11) at conventional thermostat housing are prevented by the ever-expanding form of the present entrance (20). There are equations for the present entrance (20) form geometry:

Ah ~k

Here,

Ah: Height difference

k: Pressure loss coefficient

V1 : Pre-expansion average speed, m/sn

g: Gravity

D1. Hose pre-expansion inner-diameter, m

D2. Hose post-expansion inner-diameter, m

General fluid pressure equation: P=p.g.h

For calculation of the pressure loss (DR), the height difference (Ah) is used in the pressure loss equation DR= p.g.Ah derived from the general fluid pressure equation P=p.g.h. So, it is necessary to calculate firstly the height difference value.

The equation (1) and (2) are the equations used to calculate the height difference value through the entrance (20) of the thermostat housing (10). As seen from the equation (1), the height difference value is directly proportional with the pressure loss coefficient (k) value and pre-expansion average speed (V1) value, not related to the post-expansion average speed (V2) value. It is possible to decrease the pressure drop (loss) occurred at the entrance (20) of the thermostat housing (10) by decreasing the pressure loss coefficient value or the pre-expansion average speed (V1) value. Since the pre-expansion average speed (V1) value is the average speed of the coolant before that the coolant enters the entrance (20) portion of the thermostat housing (10), the value depends on the circulation pump power used in the cooling system. So, the decrease in the pre-expansion average speed (V1) value could just be provided by using a less powerful circulation pump. However, the decrease in the coolant average speed value is not something that is desired for the efficiency of the engine cooling system. As seen from the equation (2), the pressure loss coefficient value depends on the hose diameter ratio between the coolant entering part and coolant outing part of the entrance (20). The hose pre-expansion inner-diameter (D1) refers the hose diameter at coolant entering portion of the entrance (20) while the hose post-expansion inner-diameter (D2) refers the hose diameter at coolant outing portion of the entrance (20). By increasing the hose pre-expansion inner- diameter (D1) value or decreasing the hose post-expansion inner diameter (D2) of the entrance (20), it is possible to decrease the pressure loss coefficient value, consequently the pressure loss value according to the equation (2) and (1), respectively.

As shown in figure 1c, the vortex (23) formation and the pressure drops occurred due to the sharp transition up to 90 degrees at the elbow (30) portion of the conventional thermostat housing (10) are prevented by the present elbow (30) structure in the curved form. There are also height difference equation and the pressure loss coefficient equation for the curved form geometry of the present elbow (30) structure:

(4)

Here, r: Curve radius, m

d: Inner tube diameter,

Q: Curve angle, degree

As seen from the equation (3), the pressure loss value at the elbow (30) depends on the pressure loss coefficient value of the present curved elbow (30) structure. It means that the improvement (decrease) in the pressure drop could be provided by decreasing the value of this pressure loss coefficient. The pressure loss coefficient value of the present curved elbow (30) structure depends on some major parameters which form the equation (4). The major parameters are the curve radius (r), the inner tube diameter (d) and the curve angle (Q). The curve radius (r) refers the radius formed by the coolant flow trajectory within the elbow (30) structure. The curve angle (Q) refers the angle formed between the x axis and the coolant flow orbit. Since the pressure drop coefficient value is directly proportional to these parameters, it is possible to decrease the pressure loss coefficient value, consequently the pressure loss value at the elbow (30) portion within the thermostat housing (10) by decreasing the values of these parameters. Briefly, the present thermostat housing (10) with the softer transition in the both its entrance (20) portion and its elbow (30) portion provides an improvement in the pressure drop and prevents the fluctuations and vortexes (23) caused from the abrupt geometrical transition of the conventional thermostat housing. As seen from the pressure loss coefficient equations obtained for both the entrance (20) and the elbow (30) geometry, the softer geometrical transitions formed within the present thermostat housing (10) prevent the huge pressure drops and the dead point (22) formations at corners within the housing. Besides, since there is not a huge pressure differences between the coolant portions within the present thermostat housing (10), the fluctuations and the vortex (23) formations are also prevented.

The coolant pressure distribution across the present thermostat housing (10) is shown in figure 3 and figure 4 while the coolant pressure distribution across the conventional thermostat housing is shown is figure 5 and figure 6. The housing sections where the coolant has high pressure are darkly colored in these figures. The pressure distributions are obtained as results of simulations made in Ansys simulation program. The interruption of coolant flow due to vortexes (23) occurred and sharp housing geometries within the conventional housing results in coolant accumulation consequently high pressure in particular portion of the housing. The softer geometrical transitions within the present thermostat housing prevents coolant accumulation and allows an improved coolant flow without fluctuations and vortexes (23) consequently improved pressure drop across the housing. As seen the differences in the coolant pressure distribution between conventional and present thermostat housing (10), the present housing geometry provides improved coolant flow by reducing pressure drop across housing.

Claims

1. The present invention is a thermostat housing (10) which prevents dead point (22) formation consequently the vortex (23) formation occurred due to pressure difference between coolant portions within the housing and provides improvement in the pressure drop occurred during the coolant streaming through the housing, and characterized by; to prevents formation of the dead points (22) at entrance corners (21), consequently formation of the vortex (23);

comprising an entrance (20) form which, having ever-expanding structure at near sides and top side towards the inner space of the mentioned thermostat housing (10), to prevent huge pressure drop occurred in the elbow (30) portions of the conventional thermostat housings (10);

comprising an elbow (30) form which, having softer transition geometry at corner, allows the coolant to flow softer with improved pressure drop.

2. A thermostat housing (10) according to claim 1 , wherein the pressure loss coefficient value of the entrance (20) form geometry within the thermostat housing (10) is decreased by increasing the hose pre-expansion inner-diameter (D1) value and by decreasing the hose post-expansion inner diameter (D2) of the entrance (20), according to the pressure loss coefficient equation of the entrance (20) geometry of the present invention:

3. A thermostat housing (10) according to claim 1 , wherein the pressure loss coefficient value of the elbow (30) form geometry within the thermostat housing (10) is decreased by decreasing the values of the inner tube diameter (d) and the curve angle (Q) and by increasing the values of the curve radius (r), according to the pressure loss coefficient equation of the elbow (30) geometry of the present invention: