JP7598542B2 - Flush toilet - Google Patents

Description

The present invention relates to a flush toilet, and in particular to a wash-down type flush toilet having a trap pipe including a downflow pipe and an upflow pipe.

In a flush toilet, a drain trap pipe including a descending pipe and an ascending pipe is connected to the bowl portion, and waste excreted in the bowl portion is discharged using flush water.
A variety of shapes are used for the cross section of the drain trap pipe, which is a cross section perpendicular to the central axis of the drain trap pipe. For example, in the flush toilet of Patent Document 1, the cross section of the drain trap pipe at the inlet is approximately triangular, the cross section at the lowest point is approximately rectangular, and the cross section of the riser pipe at the inlet is a combination of a circular arc and a straight line. These shapes ensure that suspended waste is discharged.

Furthermore, in the flush toilet of Patent Document 2, the cross section of the flow path of the drain trap pipe is formed into a shape that combines arcs and straight lines, or into a roughly rectangular shape, which makes it less likely for waste or paper to become clogged.

Also, in the flush toilet of Patent Document 3, the cross section of the flow path of the drain trap pipe is formed into a shape that combines a circular arc and a straight line, or into a roughly rectangular shape, and this shape improves the discharge performance of waste and flush water.

JP 2014-51883 A JP 2016-98491 A JP 2017-145631 A

On the other hand, there is a demand for the drain trap pipe of a flush toilet to have a faster start of waste discharge (initial movement), promote flow straightening in the drain trap pipe, and also increase the waste discharge speed, and there is a demand for a flush toilet that can achieve both of these.

In particular, in wash-down toilets, there is essentially no force acting to suck up flush water from within the bowl due to siphon action, so flush water and waste must be forced to overcome the drain trap pipe and be discharged only by the pushing force of flush water flowing into the bowl.

In addition, in flush toilets that clean the bowl with a swirling flow of flush water discharged from the spout, the instantaneous flow rate of the flush water discharged from the spout cannot be set high, and must be kept relatively low. This weakens the pushing force of the flush water flowing into the bowl, making it more difficult for the flush water and waste to overcome the drain trap pipe.

The present invention therefore aims to provide a flush toilet that can effectively discharge flush water and waste, even in a wash-down toilet that uses a swirling flow to clean the bowl.

To achieve the above object, the present invention is a wash-down type flush toilet, comprising a bowl section for receiving waste, a water discharge section for discharging flush water into the bowl section to form a swirling flow, a downflow conduit connected to the bowl section and extending downward from the bowl section, and a drain trap pipe including an upflow conduit connected to the downflow conduit and extending upward from the downflow conduit, the upflow conduit extending from the lowest point of the drain trap pipe to a highest point that determines the level of accumulated water in the bowl section, the upflow conduit having a flow path cross section at the lowest point formed in a substantially inverted triangle shape and a flow path cross section formed in a substantially rectangular shape over a predetermined length, and the base of the flow path cross section at the highest point being substantially horizontal and substantially linear.

According to the present invention configured in this way, the flow path cross section at the lowest point of the ascending pipe is formed in a substantially inverted triangle shape, so that the flow vector from the descending pipe to the ascending pipe can be smoothly converted, and the cleaning water can be made to flow into the ascending pipe without losing much of the energy of the flow pushed into the descending pipe from the bowl section. In addition, since the flow path cross section is formed in a substantially square shape over a predetermined length of the ascending pipe, the cleaning water flowing upward in the ascending pipe can be rectified, reducing energy loss and increasing the discharge speed of the waste. Furthermore, since the base of the flow path cross section at the highest point is formed in a substantially horizontal, substantially straight line, a wide flow path can be secured at the highest point, and a large amount of cleaning water and waste can overcome the highest point with little energy. These actions allow the cleaning water and waste to be effectively discharged.

In the present invention, the ascending pipe is preferably formed such that, in a predetermined section where the flow passage cross section is substantially rectangular, the central axis thereof is substantially linear.
According to the present invention thus configured, the central axis of a predetermined section of the flow passage having a substantially rectangular cross section is formed substantially linearly, so that clogging of the upflow pipe with sewage can be suppressed.

In the present invention, preferably, at least a portion of the riser pipe has a flow path cross-sectional area that increases from the lowest point to the highest point.
According to the present invention configured in this manner, the flow path cross-sectional area of the ascending pipe increases from the lowest point to the highest point, so that the flow velocity of the cleaning water flowing through the ascending pipe can be reduced and energy loss in the flow of the cleaning water can be suppressed.

In the present invention, the uprising pipe preferably has a flow passage cross section with a substantially constant maximum height and a substantially constant maximum width.
According to the present invention configured in this manner, the maximum height and maximum width of the flow path cross section of the uprising pipe are formed to be approximately constant, so that energy loss in the flow of cleaning water flowing through the uprising pipe can be suppressed.

In the present invention, the uprising pipe is preferably formed so that a flow passage cross section including the highest point is substantially rectangular.
According to the present invention configured in this manner, the flow path cross section including the highest point is made approximately rectangular, so that the flow path cross section over a specified length can be smoothly connected to the approximately rectangular portion of the flow path cross section at the highest point, where the base is approximately horizontal and linear, thereby suppressing disturbance in the flow of cleaning water.

In the present invention, preferably, the ascending pipe has a curved portion over a predetermined section from the lowest point, and in this curved portion, the flow path cross-sectional shape of the ascending pipe gradually changes from a substantially inverted triangular shape at the lowest point to a substantially rectangular shape.
According to the present invention configured in this manner, at the curved section, the flow path cross-sectional shape of the ascending pipe gradually changes from an approximately inverted triangular shape at the lowest point to an approximately rectangular shape, so that the flow resistance when transitioning from the approximately inverted triangular flow path cross-section to the approximately rectangular flow path cross-section can be suppressed, and cleaning water and waste can be effectively discharged.

The flush toilet of the present invention can effectively drain flush water and waste even in a wash-down toilet that uses a swirling flow to clean the bowl.

FIG. 1 is a plan view showing a flush toilet according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 2 is an enlarged cross-sectional view showing a drain trap pipe of a flush toilet according to an embodiment of the present invention. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 4 is a cross-sectional view taken along line VV in FIG. 3. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 3. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 3. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 3. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. FIG. 4 is a cross-sectional view taken along line XX in FIG. 3 . FIG. 2 is a diagram showing a schematic cross-sectional shape of an inlet portion of an ascending pipe of a drain trap pipe of a flush toilet according to an embodiment of the present invention. 1 is a cross-sectional view showing overlapping cross sections of an inlet portion and an outlet portion of a downcomer pipe. FIG. 1 is a cross-sectional view showing cross sections from an inlet of an ascending pipe to an upper cross section, the cross sections being overlapped with each other. FIG. 2 is a comparative diagram showing a trap pipe of a flush toilet according to an embodiment of the present invention and the trap pipes of Comparative Examples 1 and 2. FIG. 13 is a graph showing the relationship between the percentage of residual waste and time in the drain trap pipe of a flush toilet according to an embodiment of the present invention and the drain trap pipes of Comparative Examples 1 and 2. FIG. 16 is a partially enlarged diagram of part A in FIG. 15 .

Next, a flush toilet according to an embodiment of the present invention will be described with reference to Figs. 1 to 7. First, the basic structure of a flush toilet according to an embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig. 1 is a plan view showing a flush toilet according to an embodiment of the present invention, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1.

As shown in Figures 1 and 2, reference numeral 1 denotes a flush toilet according to an embodiment of the present invention. This flush toilet 1 is a wash-down toilet in which waste is flushed away by the flow of water caused by the difference in height between the water levels in the bowl section, and is equipped with a toilet body 2 and a water storage tank 4 that stores flushing water for cleaning the toilet body 2. The toilet body 2 is made of ceramic with a glaze layer formed on the surface, with a skirt section 6 formed on the lower part and a bowl section 8 formed in the front part of the upper half. A common water passage 10 is formed in the upper rear part of the bowl section 8, the upstream end of which is connected to the water storage tank 4, and a drain trap pipe 12 for discharging waste is formed in the lower rear part of the bowl section 8.

The above-mentioned water storage tank 4 is a flush water source, and a drain valve 14 is provided within this water storage tank 4, and the drain valve 14 is opened and closed by an operating lever (not shown). Note that this embodiment can also be applied to direct pressure flush toilets that do not have a water storage tank 4 and are supplied with flush water directly from the water supply, and flush toilets that are supplied with flush water by a flush valve, etc.

The bowl portion 8 has a bowl-shaped waste receiving surface 16, a rim portion 18 located at the upper edge, and a recess 20 formed below the waste receiving surface 16. Here, the inner peripheral surface 18a of the rim portion 18 has an inward overhanging shape, so that the swirling cleaning water does not splash out to the outside, as described below.

A first water outlet 22, which is a water outlet that discharges cleaning water, is formed on the inner peripheral surface of the rim portion 18 of the bowl portion 8, slightly rearward of the center on the left side as viewed from the front, and a second water outlet 24, which is also a water outlet, is formed on the rear right side (downstream side) as viewed from the front. These first water outlet 22 and second water outlet 24 are designed to form a swirling flow that swirls in the same direction (counterclockwise in Figure 1).

Furthermore, the common water passage 10 formed at the upper rear part of the flush toilet 1 described above branches toward the front of the toilet into a first water passage 26 and a second water passage 28. The first water passage 26 is for supplying flush water to the first water outlet 22, and the second water passage 28 is for supplying flush water to the second water outlet 24.
In this embodiment, the first water passage including the first water outlet and the second water passage including the second water outlet may be formed by a distributor or the like that is separate from the toilet body.

Here, the first water outlet 22 and the second water outlet 24 discharge wash water along the inner peripheral surface 18a of the overhanging rim portion 18, and the wash water swirling along the inner peripheral surface 18a flows down little by little to clean the inner wall surface of the bowl portion 8. At this time, the instantaneous flow rate of wash water discharged from each water outlet is controlled so that the wash water discharged from the first water outlet 22 and the second water outlet 24 does not exceed the rim portion 18 and splash out of the bowl portion 8.

Next, as shown in FIG. 2, the drain trap pipe 12 is provided with a descending pipe 32 that is connected to the lower portion 20a of the recess 20, which is a part of the recess 20 of the bowl portion 8, and extends rearward and downward, and an ascending pipe 34 that is connected to the descending pipe 32 and extends upward. Furthermore, the ascending pipe 34 is connected to a downstream drain pipe 36, and the drain pipe 36 is connected to a drain socket (not shown) or the like, so that waste is drained into a drain provided in the floor or wall.

The descending pipe 32 has an inlet 38 where the lower part 20a of the recess 20 and the descending pipe 32 are connected and switch from the lower part 20a of the recess 20 to the descending pipe 32. In this embodiment, the inlet 38 of the descending pipe 32 is the point where the rate of change in the cross-sectional area of the connection part between the lower part 20a of the recess 20 and the descending pipe 32 becomes small or zero, but the position of the inlet 38 varies slightly depending on the shape of the connection part between the lower part 20a of the recess 20 and the descending pipe 32. Furthermore, the descending pipe 32 is connected to the inlet 40 of the ascending pipe 34 at the lowest point B of the drain trap pipe 12.

The descending pipe 32 descends from the inlet 38 of the descending pipe 32 to the inlet 40 of the ascending pipe 34. The inlet 38 of the descending pipe 32 and the inlet 40 of the ascending pipe 34 are each provided as a flow path cross section perpendicular to the central axis X of the drain trap pipe. The inlet 40 is located at the lowest point B of the drain trap pipe 12. Before cleaning, at least a part of the recess 20 and the drain trap pipe 12 are filled with accumulated water to form a water seal. In this embodiment, in order to form a certain amount of water seal, the highest point T of the drain trap pipe 12 is located higher than the inlet 38 of the descending pipe 32, so that the descending pipe 32 and a part of the recess 20 connected to the descending pipe 32 can be filled with water to form a water seal. In other words, the level of the accumulated water in the bowl section 8 is determined by the height of the highest point T.

Next, the ascending pipe 34 is a pipe connected to the downstream side of the descending pipe 32 at the lowest point B, and extends from the lowest point B to the highest point T. As described later, the ascending pipe 34 has a flow path cross section formed in an approximately inverted triangle shape at the lowest point B, and a flow path cross section formed in an approximately rectangular shape in a predetermined section. Furthermore, the ascending pipe 34 has a curved section from the lowest point B to a predetermined section, and in this curved section, the shape of the flow path cross section gradually changes from an inverted triangle shape to an approximately rectangular shape. In addition, the base of the flow path cross section at the highest point T is formed in an approximately horizontal, approximately linear shape. In this embodiment, the ascending pipe 34 is formed so that the predetermined section in which the flow path cross section is formed in an approximately rectangular shape includes the highest point T.

Furthermore, a relatively wide space 35 is provided downstream of the rising pipe 34 above the highest point T, and flushing water and waste flowing out of the rising pipe 34 flow into the drain pipe 36 through this space 35. That is, during toilet flushing, the accumulated water and waste in the bowl section 8 are swept away by the flushing water flowing into the bowl section 8, and pass over the highest point T of the rising pipe 34, enter the space 35, and fall into the drain pipe 36. Here, since the cross-sectional area of the flow path formed by the space 35 is sufficiently wider than the cross-sectional area of the flow path of the rising pipe 34, even when the flushing water and waste pass over the highest point T, the space 35 is not substantially filled with water. In addition, since the cross-sectional area of the flow path of the drain pipe 36 provided downstream of the space 35 is also sufficiently wider than the cross-sectional area of the flow path of the rising pipe 34, the drain pipe 36 is not substantially filled with water. Therefore, the flush toilet 1 of this embodiment does not substantially have a siphon effect.

Next, the cross-sectional shapes of the descending pipe 32 and the ascending pipe 34 will be described with reference to Figures 3 to 9. Figure 3 is an enlarged cross-sectional view of the drain trap pipe of the toilet body. Figure 4 is a cross-sectional view taken along line IV-IV in Figure 3 (cross-sectional view of the inlet of the descending pipe), and Figure 5 is a cross-sectional view taken along line V-V in Figure 3 (cross-sectional view of the inlet of the ascending pipe). Figure 6 is a cross-sectional view taken along line VI-VI in Figure 3 (first cross-sectional view of the ascending pipe), Figure 7 is a cross-sectional view taken along line VII-VII in Figure 3 (second cross-sectional view of the ascending pipe), Figure 8 is a cross-sectional view taken along line VIII-VIII in Figure 3 (third cross-sectional view of the ascending pipe), Figure 9 is a cross-sectional view taken along line IX-IX in Figure 3 (cross-sectional view of the upper part of the ascending pipe), and Figure 10 is a cross-sectional view taken along line X-X in Figure 3 (cross-sectional view of the outlet of the ascending pipe). The cross sections of the descending pipe 32 and the ascending pipe 34 shown in Figures 4 to 10 each correspond to a "flow path cross section" cut in a direction perpendicular to the central axis of the drain trap pipe 12.

First, as shown in FIG. 4, the cross-sectional shape of the inlet 38 of the descending pipe 32 is approximately rectangular. The cross-section of the inlet 38 has an upper side 38a, a right side 38b, a lower side 38c, and a left side 38d. Here, the lower side 38c is arc-shaped, and the upper side 38a is longer in the horizontal direction than the lower side 38c. In addition, the right side 38b and the left side 38d are gently inclined inward, and are arranged so as to be symmetrical with respect to the line connecting the apex of the upper side 38a and the lowest point of the lower side 38c.

Next, as shown in FIG. 5, the cross-sectional shape of the inlet portion 40 of the ascending pipe 34 (corresponding to the outlet of the descending pipe 32) is approximately an inverted triangle. The cross-section of the inlet portion 40 has an upper side 40a, a right side 40b, and a left side 40c. Strictly speaking, the right side 40b and the left side 40c are formed in an arc shape with a relatively large radius of curvature, but the cross-section of the inlet portion 40 as a whole can be said to be approximately an inverted triangle. In addition, the point where the right side 40b and the left side 40c intersect in the cross-section of the inlet portion 40 corresponds to the lowest point B of the drain trap pipe 12. The cross-section of the inlet portion 40 is provided so as to be symmetrical with respect to the vertical axis passing through the lowest point B. Thus, in this embodiment, the flow path cross-section at the lowest point B of the ascending pipe 34 is formed in an approximately inverted triangle shape, so that the vector of the flow from the descending pipe 32 to the ascending pipe 34 can be smoothly converted. This allows the wash water to flow into the ascending pipe 34 without significantly losing the energy of the flow forced from the bowl section 8 into the descending pipe 32.

Although not shown, the cross-sectional shape of the descending pipe 32 gradually changes from an approximately square to an approximately inverted triangle from its inlet 38 toward the inlet 40 of the ascending pipe 34 (corresponding to the outlet of the descending pipe 32). In particular, the outlet side 32a (FIG. 2) of the descending pipe 32 has a cross-sectional shape of approximately an inverted triangle as shown in FIG. 5 in the range of 50 to 100 (or a shorter range including 100) of the descending pipe 32, when the inlet 38 is 0 and the inlet 40 of the ascending pipe 34 is 100. By making the rate of change of the cross-sectional shape of the descending pipe 32 constant, energy loss caused by the change in the cross-sectional shape can be further suppressed. The rate of change can also be made non-uniform as long as it is within a range in which energy loss can be suppressed to a certain extent.

Next, as shown in FIG. 6, the cross-sectional shape of the first cross section 60 of the ascending pipe 34, which is located slightly above the inlet 40 of the ascending pipe 34, is approximately pentagonal. The first cross section 60 has an upper side 60a, a right side 60b, a lower right side 60c, a left side 60d, and a lower left side 60e. Here, the right side 60b and the left side 60d are oriented in a substantially vertical direction, while the lower right side 60c and the lower left side 60e are oriented obliquely and intersect at the center. Strictly speaking, the connection of each side is rounded, but the first cross section 60 of the ascending pipe 34 as a whole can be said to be approximately pentagonal. The first cross section 60 is provided so as to be symmetrical with respect to the vertical axis passing through the intersection of the lower right side 60c and the lower left side 60e.

Next, as shown in FIG. 7, the cross-sectional shape of the second cross section 70 of the ascending pipe 34, which is located slightly above the first cross section 60, is approximately pentagonal. The second cross section 70 has an upper side 70a, a right side 70b, a lower right side 70c, a left side 70d, and a lower left side 70e. Here, the right side 70b and the left side 70d are oriented in a substantially vertical direction, while the lower right side 70c and the lower left side 70e are oriented obliquely and intersect at the center. Strictly speaking, R is attached to the connection of each side, but the second cross section 70 of the ascending pipe 34 can be said to be approximately pentagonal as a whole. In addition, the radius of curvature of R attached to the connection of each side of the second cross section 70 is larger than that of the first cross section 60. The second cross section 70 is provided so as to be symmetrical with respect to the vertical axis passing through the intersection of the lower right side 70c and the lower left side 70e.

Furthermore, as shown in FIG. 8, the third cross section 80 of the ascending pipe 34, which is located slightly above the second cross section 70, has a shape that combines a rectangle and an arc. The third cross section 80 has an upper side 80a, a right side 80b, a left side 80c, and a lower side 80d. Here, the right side 80b and the left side 80c are oriented in a generally vertical direction, and the lower side 80d is shaped like a generally arc that is convex downward. That is, the radius of curvature of the R portion that connected the lower right side 70c and the lower left side 70e in the second cross section 70 becomes even larger in the third cross section 80, and a single arc-shaped lower side 80d is formed.

Next, as shown in FIG. 9, the cross section 90 of the upper part of the rising pipe 34 is substantially rectangular. The cross section 90 of the upper part of the rising pipe 34 has an upper side 90a, a right side 90b, a left side 90c, and a bottom side 90d, and the upper side 90a is slightly longer in the horizontal direction than the bottom side 90d. The right side 90b and the left side 90c are gently inclined inward. Furthermore, the bottom side 90d can be seen as a downwardly convex arc shape with a very large radius of curvature, but can be considered to be substantially linear. The cross section of the rising pipe 34 is formed in a substantially rectangular shape that is substantially the same as the cross section shown in FIG. 9 over a predetermined section 92 (FIG. 3) that extends from slightly above the third cross section 80 toward the downstream side. In this embodiment, the central axis X of the drain trap pipe 12 in the predetermined section 92 is made straight, and this predetermined section 92 extends to the vicinity of the outlet of the rising pipe 34. In this manner, in this embodiment, the central axis X in the predetermined section 92, in which the flow passage cross section is substantially rectangular, is formed substantially linearly, so clogging of the rising pipe 34 with sewage can be suppressed. On the other hand, in the section from the cross section 40 of the inlet of the rising pipe 34 to the predetermined section 92, the pipe is curved upward so that the rising pipe 34 faces upward. By changing the cross section of this curved section, the effect of the upward curvature is mitigated, and energy loss can be suppressed.

Furthermore, in this embodiment, the cross-sectional shape is also approximately rectangular on the downstream side (upper side) of the specified section 92, and the cross-section 37 of the outlet of the rising pipe 34 shown in FIG. 10 is also formed in approximately the same rectangular shape as the cross-section 90 of the upper part of the rising pipe 34. That is, the cross-section 37 of the outlet of the rising pipe 34 has an upper side 37a, a right side 37b, a left side 37c, and a bottom side 37d. Here, as shown in FIG. 3, the cross-section 37 of the outlet of the rising pipe 34 includes the highest point T of the drain trap pipe 12. Therefore, the bottom side 37d of the outlet cross-section 37 is located at the height of the highest point T and is formed in an approximately horizontal and approximately linear shape. Thus, in this embodiment, the bottom side 37d of the flow path cross-section 37 at the highest point T is formed in an approximately horizontal and approximately linear shape, so that a wide flow path can be secured at the highest point T, and a large amount of cleaning water and dirt can overcome the highest point T with less energy.

As shown in Figures 5 to 10, the cross-sectional shape of the ascending pipe 34 is an approximately inverted triangle (Figure 5) at the inlet 40 at the upstream end, which maintains continuity with the approximately inverted triangle at the outlet side 32a of the descending pipe 32, and the cross section on the downstream side gradually approaches an approximately rectangular shape, as shown in Figures 6, 7, and 8. That is, the flow path cross-sectional shape of the ascending pipe 34 gradually changes from an approximately inverted triangle at the lowest point B to an approximately rectangular shape toward the downstream side. In this way, in this embodiment, the flow path cross-sectional shape of the ascending pipe 34 gradually changes from an approximately inverted triangle at the lowest point B to an approximately rectangular shape, so that the flow resistance when transitioning from the approximately inverted triangular flow path cross-section to the approximately rectangular flow path cross-section can be suppressed, and cleaning water and waste can be effectively discharged. In addition, in this embodiment, the cross-sectional shape of the ascending pipe 34 is approximately rectangular in the predetermined section 92 (Figure 3) of the ascending pipe 34 and its entire downstream side. In this manner, in this embodiment, the cross section of the flow path is formed in a substantially rectangular shape over a predetermined length of the rising pipe 34, so that the flush water flowing upward in the rising pipe 34 can be rectified, reducing energy loss and increasing the waste discharge speed. Preferably, the cross section of the flow path is substantially rectangular over a length of 40% to 60% of the entire length of the rising pipe 34. In addition, it is preferable that the section in which the cross section of the flow path is substantially rectangular is set in a range from the downstream end (highest point T) of the rising pipe 34 to 40% to 60% of the entire length of the rising pipe 34.

Furthermore, as shown in Figures 4 to 10, in this embodiment, the maximum height H1 of the cross section perpendicular to the central axis X of the inlet 38 of the descending pipe 32, the maximum height H2 of the cross section perpendicular to the central axis X of the inlet 40 of the ascending pipe 34, the maximum height H3 of the first cross section perpendicular to the central axis X of the ascending pipe 34, the maximum height H4 of the second cross section perpendicular to the central axis X of the ascending pipe 34, the maximum height H5 of the third cross section perpendicular to the central axis X of the ascending pipe 34, the maximum height H6 of the upper cross section perpendicular to the central axis X of the ascending pipe 34, and the maximum height H7 of the outlet cross section perpendicular to the central axis X of the ascending pipe 34 are approximately constant. Therefore, the maximum height of the cross section perpendicular to the central axis X of the drain trap pipe 12 is approximately constant.

Also, as shown in Figures 4 to 10, in this embodiment, the maximum width W2 of the cross section perpendicular to the central axis X of the inlet portion 40 of the rising pipe 34, the maximum width W3 of the first cross section perpendicular to the central axis X of the rising pipe 34, the maximum width W4 of the second cross section perpendicular to the central axis X of the rising pipe 34, the maximum width W5 of the third cross section perpendicular to the central axis X of the rising pipe 34, the maximum width W of the upper cross section perpendicular to the central axis X of the rising pipe 34, and the maximum width W7 of the outlet cross section perpendicular to the central axis X of the rising pipe 34 are approximately constant. Therefore, the maximum width W of the cross section perpendicular to the central axis X of the rising pipe 34 is approximately constant. Thus, in this embodiment, the maximum height and maximum width of the flow passage cross section of the rising pipe 34 are formed to be approximately constant, so that the energy loss of the flow of the cleaning water flowing in the rising pipe 34 can be suppressed. On the other hand, the maximum width W1 of the cross section perpendicular to the central axis X of the inlet 38 of the descending pipe 32 is narrower than the maximum width W2 of the cross section perpendicular to the central axis X of the inlet 40 of the ascending pipe 34.

Next, the cross-sectional shape of the inlet portion 40 of the rising pipe 34 will be described in detail with reference to Figure 11. Figure 11 is a schematic diagram showing the cross-sectional shape of the inlet portion of the rising pipe of the drain trap pipe of a flush toilet according to an embodiment of the present invention.
As shown in Fig. 11, the cross-sectional shape of the inlet portion 40 of the rising pipe 34 is an approximately inverted triangle as described above. The approximately inverted triangle shape will be specifically described. Fig. 11 shows the shape of the inner wall of the inlet portion 40 of the rising pipe 34. The inlet portion 40 has an approximately triangular cross-sectional shape due to an upper side 42, a first right side edge 44, a second right side edge 46 connected to the first right side edge 44 by a connecting portion 45, a first left side edge 48, and a second left side edge 50 connected to the first left side edge 48 by a connecting portion 49. The upper side 42, the first right side edge 44, the second right side edge 46, the first left side edge 48, and the second left side edge 50 are all approximately arc-shaped.

The center of the upper side 42 of the inlet portion 40 of the ascending pipe 34 is the upper end 51 of the cross section, and the intersection of the second right side 46 and the second left side 50 is the lower end 52 of the cross section.
Here, in the cross section of the inlet 40 of the rising pipe 34, the height (distance) b from the connecting parts 45, 49 to the lower end 52 is greater than the height (distance) a from the upper end 51 to the connecting parts 45, 49 (i.e., there is a relationship of b>a). The cross-sectional shape of the inlet 40 is provided so as to be symmetrical with respect to the line connecting the upper end 51 and the lower end 52.

As shown in FIG. 11 , the cross section of the inlet portion 40 of the ascending pipe 34 is shaped so that the inward inclination angle β of the second right side edge 46 with respect to the vertical direction (specifically, the inclination angle of a tangent drawn at the midpoint of the second right side edge 46 with respect to the vertical direction) is greater than the inward inclination angle α of the first right side edge 44 with respect to the vertical direction (specifically, the inclination angle of a tangent drawn at the midpoint of the first right side edge 44 with respect to the vertical direction) (i.e., there is a relationship of β > α).
Similarly, the cross section of the inlet portion 40 of the ascending pipe 34 is shaped so that the inward inclination angle β of the left second side edge 50 with respect to the vertical direction (specifically, the inclination angle of the tangent line drawn at the midpoint of the left second side edge 50 with respect to the vertical direction) is greater than the inward inclination angle α of the left first side edge 48 with respect to the vertical direction (specifically, the inclination angle of the tangent line drawn at the midpoint of the left first side edge 48 with respect to the vertical direction) (i.e., there is a relationship of β > α).

Furthermore, as shown in FIG. 11, in the cross section of the inlet 40 of the ascending pipe 34, the angle γ formed by the tangent drawn at the center point of the second right side edge 46 and the tangent drawn at the center point of the second left side edge 50 is 105 degrees. Here, the angle γ is preferably between 85 degrees and 125 degrees. The angle γ is larger than the angles formed by the top edge 42 and the first left side edge 48 and the first right side edge 44.

Next, the cross-sectional areas of the inlet 38 and outlet (corresponding to the inlet 40 of the uprising pipe 34) of the downcomer pipe 32 will be described with reference to Fig. 12. Fig. 12 is a cross-sectional view showing the cross sections of the inlet and outlet of the downcomer pipe overlapping each other.
As shown in Fig. 12, the cross-sectional shape of the inlet 38 of the descending pipe 32 is shown by an imaginary line, and the cross-sectional shape of the outlet is shown by a solid line. Here, the cross-sectional area S1 of the inlet 38 and the cross-sectional area S2 of the outlet are substantially the same. Therefore, the cross-sectional height H1 of the inlet 38 and the cross-sectional height H2 of the outlet are substantially constant, so that the cross-sectional area is substantially constant by making the cross-sectional width W1 of the inlet 38 larger than the cross-sectional width W2 of the outlet (inlet 40 of the ascending pipe 34). In addition, compared to the substantially rectangular inlet 38, the outlet (inlet 40 of the ascending pipe 34) is substantially inverted triangular, so that the bottom of the cross section is narrower.

Next, the cross-sectional area of each part of the ascending pipe 34 will be described with reference to Figure 13. Figure 13 is a cross-sectional view showing the cross sections of the ascending pipe 34 from the inlet 40 to the upper cross section 90, which are overlapped. In Figure 13, the inlet 40 (Figure 5) is shown by a thick solid line, the first cross section 60 (Figure 6) is shown by a dashed line, the second cross section 70 (Figure 7) is shown by a dashed line, the third cross section 80 (Figure 8) is shown by a two-dot chain line, and the upper cross section 90 (Figure 9) is shown by a thin solid line.

As described above, the maximum heights H2 to H6 of each cross section from the inlet 40 of the rising pipe 34 to the upper cross section 90 are approximately constant, and the maximum widths W2 to W6 of each cross section are also approximately constant. Thus, the maximum height and maximum width of each cross section of the rising pipe 34 are approximately constant, while the cross-sectional shape gradually changes from the approximately inverted triangular shape of the inlet 40 to the approximately rectangular shape of the upper cross section 90. Therefore, the cross section of the rising pipe 34 gradually expands from the approximately inverted triangular shape of the inlet 40 to the approximately rectangular shape of the upper cross section 90, and the flow path cross-sectional area of the rising pipe 34 increases from the lowest point B to the highest point T. In this way, in this embodiment, since the flow path cross-sectional area of the rising pipe 34 increases from the lowest point B to the highest point T, the flow velocity of the cleaning water flowing through the rising pipe 34 can be reduced, and the energy loss of the flow of the cleaning water can be suppressed.

The cross section of the ascending pipe 34 is configured so that the cross-sectional area of the flow path becomes wider in the lower part from the lowest point B to the highest point T, so that less energy is required to push up the waste with the washing water. In order to discharge the waste from the ascending pipe 34, it is necessary to push the waste up against gravity, but if the cross-sectional area of the flow path is narrow in the lower part of the ascending pipe 34, more washing water and waste must be pushed up to the top in order to drain the same amount of washing water and waste. This may increase the energy loss of the washing water flow. In contrast, in this embodiment, the cross-sectional area of the flow path in the lower part of the ascending pipe 34 is configured to be wide, so less waste needs to be pushed up to the top of the flow path cross-section, and energy loss can be suppressed.

Next, the three characteristics required for a flush toilet, "speed of discharge start," "straightening of flow in the downflow pipe," and "discharge speed," will be explained by comparing flush toilet 1 according to this embodiment with flush toilets according to comparative examples 1 and 2, which are conventional technology. Figure 14 is a comparison diagram showing a comparison of the trap pipe of a flush toilet according to an embodiment of the present invention and the trap pipes of comparative examples 1 and 2, Figure 15 is a diagram showing the relationship between the residual waste rate and time for the drain trap pipe of a flush toilet according to an embodiment of the present invention and the drain trap pipes of comparative examples 1 and 2, and Figure 16 is a partially enlarged diagram of part A in Figure 15.

First, both Comparative Example 1 and Comparative Example 2 are conventional "wash-down toilets." In the flush toilet of Comparative Example 1, the cross-sectional shape perpendicular to the central axis at the inlet of the downflow pipe is approximately rectangular, the cross-sectional shape perpendicular to the central axis at the inlet of the upflow pipe is approximately rectangular, and the cross-sectional shape perpendicular to the central axis at the upper part of the upflow pipe is approximately rectangular.
In the flush toilet of Comparative Example 2, the cross-sectional shape perpendicular to the central axis at the inlet of the downflow pipeline is approximately an inverted triangle, the cross-sectional shape perpendicular to the central axis at the inlet of the upflow pipeline is approximately a rectangle, and the cross-sectional shape perpendicular to the central axis at the upper part of the upflow pipeline is approximately a rectangle.
In the flush toilet 1 of this embodiment, as described above, the cross-sectional shape perpendicular to the central axis at the inlet of the downflow pipeline is approximately rectangular, the cross-sectional shape perpendicular to the central axis at the inlet of the upflow pipeline is approximately inverted triangular, and the cross-sectional shape perpendicular to the central axis at the upper part of the upflow pipeline is approximately rectangular.

In order to confirm the three characteristics described above of the flush toilets according to Comparative Example 1, Comparative Example 2, and the embodiment, experiments were also conducted using artificial filth (using a large amount of fine particles with roughly the same mass as filth), and the results shown in Figures 15 and 16 were obtained.
First, as shown in FIG. 14, in terms of "speed of discharge start (initial movement)," the flush toilets according to Comparative Example 1 and the embodiment were fast (◯), while Comparative Example 2 was a little slower (Δ).
With regard to flow straightening within the downflow pipe, the flush toilets according to Comparative Example 2 and the embodiment were good (◯), while Comparative Example 1 was poor (Δ).
Regarding waste discharge speed, the flush toilets according to Comparative Example 1 and the embodiment were fast (◯), while Comparative Example 2 was slightly slower (Δ).

Next, as shown in Figures 15 and 16, when waste is discharged from the bowl section into the drain trap pipe, there is 100% waste in the bowl section when the discharge begins (0 seconds), and when the discharge ends, there is no waste left in the bowl (almost zero).
Two seconds after flushing begins, the waste in the bowl begins to be discharged into the drain trap pipe due to the flow of water caused by the difference in height between the water levels in the bowl. At this time, as shown in Figure 16, the flush toilet of this embodiment shown by the solid line begins to discharge waste the fastest, followed by the flush toilet of Comparative Example 1 shown by the dashed line, and the flush toilet of Comparative Example 2 shown by the dashed line.

From the above, it has been confirmed that the flush toilet according to this embodiment has three characteristics required for a flush toilet: "speed of discharge start," "straightening of the flow in the downcomer pipe," and "discharge speed."

Next, the effects of the flush toilet according to the embodiment of the present invention described above will be explained.
According to the flush toilet of the embodiment of the present invention, the cross section at the lowest point B of the rising pipe 34 (cross section at the inlet portion 40 of the rising pipe 34) is formed in a substantially inverted triangle shape (FIG. 5), so the vector of the flow from the descending pipe 32 to the rising pipe 34 can be smoothly converted, and flush water can be made to flow into the rising pipe 34 without losing much of the energy of the flow forced into the descending pipe 32 from the bowl portion 8. In addition, since the cross section 90 is formed in a substantially square shape (FIG. 9) over a predetermined length of the rising pipe 34, the flush water flowing upward in the rising pipe 34 can be rectified, reducing energy loss and increasing the discharge speed of waste. Furthermore, since the base 37d of the cross section 37 at the highest point T is formed in a substantially horizontal, substantially straight line (FIG. 10), a wide flow path can be secured at the highest point T, and a large amount of flush water and waste can overcome the highest point T with little energy. These actions allow flush water and waste to be effectively discharged.

In addition, with the flush toilet of this embodiment, the central axis X in the predetermined section 92 of the approximately rectangular cross section (Figure 9) is formed in an approximately straight line (Figure 3), which makes it possible to prevent clogging of the rising pipe 34 with waste.

Furthermore, in the flush toilet of this embodiment, the flow path cross-sectional area of the rising pipe 34 increases from the lowest point B to the highest point T (Figure 13), so the flow velocity of the flush water flowing through the rising pipe 34 can be reduced, and energy loss in the flow of the flush water can be suppressed.

In addition, with the flush toilet of this embodiment, the maximum height (H2 to H7) and maximum width (W2 to W7) of the cross section of the rising pipe 34 are formed to be approximately constant (Figure 13), so energy loss in the flow of flush water flowing through the rising pipe 34 can be suppressed.

Furthermore, according to the flush toilet of this embodiment, the cross section 37 (Figure 10) including the highest point T is made to be approximately rectangular, so that the portion having an approximately rectangular cross section over a certain length can be smoothly connected to the cross section 37 of the outlet at the highest point T, where the base 37d is approximately horizontal and linear, thereby suppressing turbulence in the flow of flush water.

The above describes an embodiment of the present invention, but various modifications can be made to the above-described embodiment.

1 Flush toilet 2 Toilet body 8 Bowl portion 12 Drain trap pipe 22 First water outlet (water outlet portion)
24 Second outlet (water outlet section)
32 Downstream pipe 32a Outlet side 34 Upstream pipe 34a Upper side 34b Right side 34c Lower side 34d Left side 38 Inlet 38a Upper side 38b Right side 38c Lower side 38d Left side 40 Inlet 40a Upper side 40b Right side 40c Left side 42 Upper side 44 First right side 45, 49 Connection point 46 Second right side 48 First left side 50 Second left side 51 Upper end 52 Lower end

Claims (6)

A wash-down type flush toilet,
A bowl portion for receiving waste;
a water discharge section that discharges wash water into the bowl section to form a swirling flow;
a drain trap pipe including a downcomer pipe connected to the bowl portion and extending downward from the bowl portion, and an upcomer pipe connected to the downcomer pipe and extending upward from the downcomer pipe,
the riser conduit extends from a lowest point of the drain trap conduit to a highest point defining a water level within the bowl portion;
a flush toilet wherein the ascending pipe has a flow path cross section formed in a substantially inverted triangular shape at the lowest point and a substantially rectangular shape over a predetermined length, and the base of the flow path cross section at the highest point is substantially horizontal and substantially straight. The flush toilet according to claim 1, wherein the central axis of the rising pipe is formed in a substantially straight line in a predetermined section where the flow passage cross section is substantially rectangular. A flush toilet according to claim 1 or 2, in which the cross-sectional area of the flow path of at least a portion of the rising pipe increases from the lowest point to the highest point. A flush toilet according to any one of claims 1 to 3, wherein the maximum height and maximum width of the cross section of the ascending pipe are substantially constant. A flush toilet according to any one of claims 1 to 4, wherein the cross section of the ascending pipe including the highest point is formed in a substantially rectangular shape. A flush toilet according to any one of claims 1 to 5, wherein the rising pipe has a curved section extending from the lowest point over a predetermined distance, and in this curved section, the cross-sectional shape of the flow path of the rising pipe gradually changes from a substantially inverted triangular shape at the lowest point to a substantially rectangular shape.

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