Water-washable toilet

Abstract

For example, the present invention provides a flush toilet that can stably flush the bowl even if the amount of flushing water stored in the flushing water tank is changed. [Solution] The present invention relates to a flush toilet 1, comprising a bowl portion 6 having a waste receiving surface 10 and a rim portion 12, a drain trap pipe 8, a first rim outlet 18, a second rim outlet 20, a common water channel 22 connected to a flush water supply source, a first rim water channel 24 branching from the downstream end of the common water channel 22 and connecting to the first rim outlet 18, and a second rim water channel 26 branching from the downstream end of the common water channel 22 and connecting to the second rim outlet 20, wherein the common water channel 22 is provided with a constricted portion 32 having the smallest flow path cross-sectional area of ​​the common water channel 22, and the constricted portion 32 is set so that both the width W3 and height H3 of the flow path cross-section are the smallest of the common water channel 22.

Description

Technical Field

[0001] The present invention relates to a flushing toilet, and particularly to a flushing toilet that discharges dirt by washing with washing water.

Background Art

[0002] Conventionally, as described in, for example, Patent Document 1, there is known a flushing toilet provided with a washing water tank for storing washing water, and the washing water in the washing water tank is discharged from a rim spout of a bowl portion. In such a flushing toilet, the washing water discharged from the rim spout is washed by swirling in the bowl portion.

[0003] Further, in the flushing toilet described in Patent Document 1, when the amount of washing water stored in the washing water tank is changed, a throttle portion is provided in a water conduit connecting the washing water tank and the rim spout so that the flow rate of the washing water discharged from the rim spout does not change. The cross-sectional area of the flow path of the throttle portion is set to be smaller than the opening area of the rim spout, and when the amount of washing water supplied from the washing water tank is large, the flow rate of the washing water discharged from the rim spout is reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the flush toilet described in Patent Document 1 mentioned above, the width of the constricted section is kept the same as the width of the water conduit, and the vertical width of the constricted section is reduced, thereby reducing the cross-sectional area of ​​the flow path in the constricted section. As a result, when the amount of flushing water stored in the flushing water tank increases, the flow rate of the flushing water discharged from the rim outlet changes, which causes a problem in which an unwashed area occurs in the bowl.

[0006] Therefore, the present invention has been made to solve the above-mentioned problems, and aims to provide a flush toilet that can stably clean the bowl even if, for example, the amount of flushing water stored in the flushing water tank is changed. [Means for solving the problem]

[0007] To solve the above-mentioned problems, the present invention provides a flush toilet that washes and discharges waste with flushing water, comprising: a bowl portion having a waste receiving surface for receiving waste and a rim portion formed above the waste receiving surface; a drain trap pipe connected below the bowl portion for discharging waste; a first rim outlet provided in the rim portion for discharging flushing water and forming a swirling flow; and a swirling flow provided in the rim portion for discharging flushing water and swirling in the same direction as the flushing water discharged from the first rim outlet. The system comprises a second rim discharge port, a common water channel connected to a washing water supply source, a first rim water channel branching off from the downstream end of the common water channel and connecting to the first rim discharge port, and a second rim water channel branching off from the downstream end of the common water channel and connecting to the second rim discharge port. The common water channel is provided with a constricted section that has the smallest flow channel cross-sectional area, and the constricted section is characterized in that both the width and height of the flow channel cross-section are set to be the smallest among the common water channels.

[0008] According to the present invention configured in this way, the common water conduit is provided with a constricted section having the smallest cross-sectional area of ​​the common water conduit, and the constricted section is set so that both the width and height of the cross-sectional area of ​​the flow path are the smallest in the common water conduit. Therefore, even if the amount of cleaning water stored in the cleaning water tank is changed, for example, the flow rate of cleaning water discharged from the first rim outlet and the second rim outlet remains unchanged, and the bowl can be cleaned stably.

[0009] In the present invention, preferably, the throttling portion is formed to be inclined downward toward the downstream side. In the present invention configured in this way, the throttling portion is formed to be inclined downward toward the downstream side, so that the flow rate of the cleaning water discharged from the first rim outlet and the second rim outlet can be kept constant by the throttling portion without reducing the force of the cleaning water.

[0010] Furthermore, in the present invention, preferably, a narrowing section is provided upstream of the throttling section, where the cross-sectional area of ​​the flow path gradually decreases toward the downstream side. In the present invention configured in this way, a narrowing section is provided upstream of the narrowing section, in which the cross-sectional area of ​​the flow path gradually decreases toward the downstream side. This allows the cleaning water to flow toward the narrowing section while suppressing pressure loss.

[0011] In the present invention, preferably, an expanding section is provided downstream of the constricted section, where the cross-sectional area of ​​the flow path gradually increases toward the downstream side. In the present invention configured in this way, an expanding section is provided downstream of the constricted section, where the flow path cross-sectional area gradually expands toward the downstream side. As a result, the cleaning water flows along the inner circumferential surface of the expanding section and can be divided into the first rim water channel and the second rim water channel.

[0012] Furthermore, in the present invention, preferably, in a plan view, the radius of curvature of the inner surface at the portion where the common water channel bends to the first rim water channel is set to be larger than the radius of curvature of the inner surface at the portion where the common water channel bends to the second rim water channel. In the present invention configured as described above, in a plan view, the radius of curvature of the inner surface at the point where the common water channel bends into the first rim water channel is set to be larger than the radius of curvature of the inner surface at the point where the common water channel bends into the second rim water channel. Therefore, more cleaning water can flow through the first rim water channel than through the second rim water channel.

[0013] In the present invention, preferably, in a plan view, the lengths of the reduction portion, the aperture portion, and the expansion portion in the front-to-back direction are set to be substantially the same. In the present invention configured in this way, in a plan view, the lengths of the reduction section, the narrowing section, and the expansion section in the front-to-back direction are set to be approximately the same, so that the common water channel can be filled with water quickly, and cleaning water can be discharged quickly from the first rim outlet and the second rim outlet.

[0014] Furthermore, in the present invention, preferably, the constricted portion is formed by a curved surface at each of the four corners of the cross-section of the flow path. In the present invention configured in this way, since the constricted portion is formed by curved surfaces at each of the four corners of the flow path cross-section, the flow rate of the cleaning water discharged from the first rim outlet and the second rim outlet can be kept constant by the constricted portion while suppressing pressure loss.

[0015] Furthermore, in the present invention, preferably, a stepped portion is formed in the first rim water channel to reduce the cross-sectional area of ​​the flow path. In the present invention configured in this way, a stepped portion is formed in the first rim water conduit to reduce the cross-sectional area of ​​the flow path, so that the amount of cleaning water discharged from the first rim outlet can be adjusted. [Effects of the Invention]

[0016] According to the flush toilet of the present invention, the bowl can be stably flushed even if, for example, the amount of flushing water stored in the flushing water tank is changed. [Brief explanation of the drawing]

[0017] [Figure 1] It is a side sectional view of a water-washing toilet according to an embodiment of the present invention. [Figure 2] It is a sectional view taken along line II-II of FIG. 1. [Figure 3] It is a perspective view of a common water passage of a water-washing toilet according to an embodiment of the present invention. [Figure 4] It is an enlarged view of the common water passage portion of FIG. 2. [Figure 5] It is a sectional view taken along line V-V of FIG. 4. [Figure 6A] It is a sectional view taken along line A-A of FIG. 5. [Figure 6B] It is a sectional view taken along line B-B of FIG. 5. [Figure 6C] It is a sectional view taken along line C-C of FIG. 5. [Figure 6D] It is a sectional view taken along line D-D of FIG. 5.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, a water-washing toilet according to an embodiment of the present invention will be described with reference to the drawings. First, referring to FIGS. 1 and 2, the overall structure of the water-washing toilet according to the present embodiment will be described. FIG. 1 is a side sectional view of the water-washing toilet according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. 1. In this specification, in the state where the user views the water-washing toilet from the front, the front side of the water-washing toilet will be described as "front", the back side as "rear", the right side as "right", and the left side as "left".

[0019] As shown in FIGS. 1 and 2, the water-washing toilet 1 includes a toilet body 2 made of pottery and a washing water tank 4 (washing water supply source) for storing washing water to be supplied to the toilet body 2. The water-washing toilet 1 of the present embodiment is configured such that by operating a button 4a provided on the upper surface of the washing water tank 4, the washing water stored in the washing water tank 4 is supplied to the toilet body 2. Further, the water-washing toilet 1 of the present embodiment is a flushing type toilet that flushes away dirt by the flowing water action due to the drop of the washing water.

[0020] The toilet body 2 comprises a bowl-shaped bowl section 6, a drain trap pipe 8 connected below the bowl section 6 for discharging waste, and a skirt section 9 that covers the bowl section 6 and the drain trap pipe 8 from the outside. The drain trap pipe 8 comprises an inlet 8a, an introduction pipe 8b descending from the inlet 8a, an ascending pipe 8c rising from the downstream end of the introduction pipe 8b, a horizontal pipe 8d extending rearward from the downstream end of the ascending pipe 8c, and a top section 8e located between the ascending pipe 8c and the horizontal pipe 8d. A drain socket (not shown) is attached to the downstream end of the horizontal pipe 8d of the drain trap pipe 8 and is connected to a drain pipe (not shown) provided on the floor.

[0021] The bowl section 6 comprises a waste receiving surface 10 for receiving waste, a rim section 12 formed above the waste receiving surface 10, a shelf surface 14 formed between the waste receiving surface 10 and the rim section 12, and a pot section 16 formed below the waste receiving surface 10, in which water is collected. The rim section 12 is provided with a first rim outlet 18 for discharging cleaning water toward the front of the bowl section 6 and a second rim outlet 20 for discharging cleaning water toward the rear of the bowl section 6. The first rim outlet 18 is located on the left rear side of the bowl section 6, and the second rim outlet 20 is located on the right rear side of the bowl section 6. The cleaning water discharged from the first rim outlet 18 and the second rim outlet 20 flows down the shelf surface 14, forming a swirling flow that swirls in the same direction, and cleans the waste receiving surface 10.

[0022] The rear interior of the toilet bowl body 2 is provided with a common water channel 22 that connects to the drain port 4b of the flushing water tank 4, a first rim water channel 24 that branches off from the downstream end of the common water channel 22 and connects to the first rim outlet 18, and a second rim water channel 26 that branches off from the downstream end of the common water channel 22 and connects to the second rim outlet 20. The ratio of the amount of flushing water supplied from the flushing water tank 4 to the amount of flushing water discharged from the first rim outlet 18 to the amount of flushing water discharged from the second rim outlet 20 is set to approximately 7:3.

[0023] The common water channel 22 is a flow path for guiding the flushing water discharged from the flushing water tank 4 towards the bowl section 6. The common water channel 22 extends from the drain outlet 4b of the flushing water tank 4 to the vicinity of the rear of the bowl section 6. Furthermore, the common water channel 22 extends in a straight line along the left-right center line of the toilet body 2. In addition, the common water channel 22 is located directly above the drain trap pipe 8.

[0024] The first rim water channel 24 is a channel for guiding the cleaning water flowing in from the common water channel 22 to the first rim outlet 18. The first rim water channel 24 extends from the downstream end of the common water channel 22 to the first rim outlet 18. The first rim water channel 24 also extends to the left front while curving along the bowl section 6.

[0025] The second rim water channel 26 is a channel for guiding the cleaning water flowing in from the common water channel 22 to the second rim outlet 20. The second rim water channel 26 extends from the downstream end of the common water channel 22 to the second rim outlet 20. Furthermore, the second rim water channel 26 curves along the bowl section 6 and extends forward to the right, then makes a U-turn and extends backward to the left.

[0026] The flushing water tank 4 is mounted on the rear upper surface of the toilet bowl body 2. Inside the flushing water tank 4, there is a drain valve device 4c that opens and closes the drain port 4b in response to the operation of a button 4a. The flushing water tank 4 is configured so that the supply of flushing water from the flushing water tank 4 to the toilet bowl body 2 can be switched on or off by the opening and closing of the drain port 4b by the drain valve device 4c. In addition, the flushing water tank 4 is configured so that the amount of flushing water stored inside the flushing water tank 4 can be changed.

[0027] Next, with reference to Figures 3 to 5 and 6A to 6D, the common water supply channel of the flush toilet according to this embodiment will be described in detail. Figure 3 is a perspective view of the common water conduit of a flush toilet according to an embodiment of the present invention, Figure 4 is an enlarged view of the common water conduit portion of Figure 2, Figure 5 is a cross-sectional view along line VV in Figure 4, and Figures 6A to 6D are cross-sectional views along lines AA to DD in Figure 5. Figures 6A to 6D are cross-sectional views of the flow path perpendicular to the direction in which the flushing water flows.

[0028] As shown in Figures 3 and 4, the common water conduit 22 is provided with, from the upstream side, a connection port 22a for connecting to the wash water tank 4, a narrowing section 30 where the flow path cross-sectional area is reduced, a constricting section 32 where the flow path cross-sectional area is minimized, and an expanding section 34 where the flow path cross-sectional area is increased. Thus, the flow path cross-sectional area of ​​the common water conduit 22 is set to be smallest at the constricting section 32. In addition, in a plan view, the lengths (L1, L2, and L3) in the front-to-back direction of the narrowing section 30, the constricting section 32, and the expanding section 34 are set to be approximately the same (see Figure 4).

[0029] The connection port 22a is an opening for allowing the cleaning water discharged from the cleaning water tank 4 to flow into the common water conduit 22. The connection port 22a is formed on the upper surface 22b of the common water conduit 22 and is formed in a circular shape that is substantially the same as the drain port 4b of the cleaning water tank 4.

[0030] As shown in Figures 5 and 6A, the common water channel 22 directly below the connection port 22a is configured to have the largest flow channel cross-sectional area among the common water channels 22. This allows the washing water flowing in from the connection port 22a to flow smoothly downstream. Furthermore, the flow channel cross-section of the common water channel 22 directly below the connection port 22a is formed in a rectangular shape, and the vertical width H1 is set to be smaller than the horizontal width W1 (see Figure 6A).

[0031] As shown in Figures 4 and 5, the reducing section 30 is a flow path for guiding the cleaning water to the squeezing section 32. The reducing section 30 is formed near the connection port 22a and extends forward. The flow path cross-sectional area of ​​the reducing section 30 gradually decreases toward the downstream side. The widths W2a and W2b of the reducing section 30 gradually decrease toward the downstream side (see Figure 4). Also, the vertical width H2 of the reducing section 30 gradually decreases toward the downstream side (see Figure 5). The reducing section 30 is formed to slope downward toward the downstream side. In addition, the upper surface 30a of the reducing section 30 slopes downward toward the downstream side at a larger angle than the bottom surface 30b of the reducing section 30 (see Figure 5).

[0032] As shown in Figures 5 and 6B, the flow channel cross-section of the reduced section 30 is formed in a trapezoidal shape, and the width W2a of the upper surface 30a is set to be smaller than the width W2b of the lower surface 30b. Also, the vertical width H2 of the reduced section 30 is set to be larger than the width W2a of the upper surface 30a and smaller than the width W2b of the lower surface 30b. In the flow channel cross-section of the reduced section 30, the region below the vertical center line CL is set to be larger than the region above it.

[0033] As shown in Figures 4 and 5, the throttling section 32 is a flow path for adjusting and keeping the flow rate of the cleaning water supplied from the cleaning water tank 4 approximately constant. The throttling section 32 is located between the narrowing section 30 and the expanding section 34 and extends forward. The flow path cross-sectional area of ​​the throttling section 32 is set to be the smallest among the common water conduits 22. Furthermore, the flow path cross-sectional area of ​​the throttling section 32 is set to be smaller than the sum of the opening areas of the first rim outlet 18 and the second rim outlet 20. In addition, the flow path cross-sectional area of ​​the throttling section 32 is set to be smaller than the opening area of ​​the drain port 4b of the cleaning water tank 4 (or the opening area of ​​the connection port 22a). Moreover, the flow path cross-sectional area of ​​the throttling section 32 is set to be constant over the length L2 of the throttling section 32.

[0034] As shown in Figures 5 and 6C, the flow path cross-section of the throttling section 32 is formed in a flattened rectangular shape. The shape of the flow path cross-section of the throttling section 32 is formed to be constant over the length L2 of the throttling section 32. The width W3 of the throttling section 32 is set to be larger than the height H3 of the throttling section 32. In this embodiment, the width W3 of the throttling section 32 is set to be approximately 40 mm, and the height H3 of the throttling section 32 is set to be approximately 22 mm. Furthermore, the width W3 of the throttling section 32 is set to be the smallest among the common water conduits 22. In addition, the width W3 of the throttling section 32 is set to be smaller than the inner diameter of the drain port 4b of the washing water tank 4 (or the inner diameter of the connection port 22a). Furthermore, the height H3 of the throttling section 32 is set to be the smallest among the common water conduits 22. Thus, both the width W3 and height H3 of the throttling section 32 are set to be the smallest among the common water conduits 22. Furthermore, the constricted portion 32 is formed by curved surfaces with approximately the same radius of curvature at each of the four corners 34c of the flow channel cross-section.

[0035] As shown in Figure 5, the aperture portion 32 is formed to incline downward toward the downstream side. Furthermore, the upper surface 32a of the aperture portion 32 is inclined downward at the same angle as the bottom surface 32b of the aperture portion 32 (see Figure 5). In other words, the upper surface 32a of the aperture portion 32 is parallel to the bottom surface 32b of the aperture portion 32.

[0036] As shown in Figures 4 and 5, the enlarged section 34 is a flow path for guiding cleaning water from the constricted section 32 to the first rim water channel 24 and the second rim water channel 26. The enlarged section 34 is provided between the constricted section 32 and the first rim water channel 24 and the second rim water channel 26, and extends forward. The flow path cross-sectional area of ​​the enlarged section 34 gradually increases toward the downstream side. The width W4 of the enlarged section 34 gradually increases toward the downstream side (see Figure 4). Also, the vertical width H4 of the enlarged section 34 gradually increases toward the downstream side (see Figure 5). Furthermore, the upper surface 34a of the enlarged section 34 inclins upward toward the forward side and then extends horizontally, and the bottom surface 34b of the enlarged section 34 inclins downward toward the forward side and then extends horizontally (see Figure 5).

[0037] As shown in Figures 5 and 6D, the cross-sectional shape of the flow channel of the enlarged section 34 is formed as a flattened rectangular shape. The width W4 of the enlarged section 34 is set to be greater than the height H4 of the enlarged section 34.

[0038] As shown in Figure 4, in a plan view, the radius of curvature R1 of the inner surface at the point where the common water channel 22 bends into the first rim water channel 24 is set to be larger than the radius of curvature R2 of the inner surface at the point where the common water channel 22 bends into the second rim water channel 26. As a result, more cleaning water flows into the first rim water channel 24 than into the second rim water channel 26.

[0039] As shown in Figures 3 and 4, a stepped portion 24a projecting upward is formed on the bottom surface of the first rim water channel 24. This reduces the cross-sectional area of ​​the flow path of the first rim water channel 24, thereby adjusting the amount of cleaning water discharged from the first rim outlet 18.

[0040] Next, the effects and advantages of the flush toilet 1 according to this embodiment described above will be explained. First, in the flush toilet 1 according to this embodiment, the common water channel 22 is provided with a constricted section 32 which has the smallest flow path cross-sectional area within the common water channel 22. The constricted section 32 is set so that both the width W3 and height H3 of the flow path cross-section are the smallest within the common water channel 22. Therefore, even if the amount of flushing water stored in the flushing water tank 4 is changed, for example, the flow rate of flushing water discharged from the first rim outlet 18 and the second rim outlet 20 remains unchanged, and the bowl 6 can be stably flushed. In addition, since the width W3 of the constricted section 32 is small without the height H3 becoming too small, the manufacturability of the ceramic toilet bowl body 2 can be improved.

[0041] In the flush toilet 1 according to this embodiment, the restrictor portion 32 is formed to be inclined downward toward the downstream side, so that the flow rate of flushing water discharged from the first rim outlet 18 and the second rim outlet 20 can be kept constant by the restrictor portion 32 without reducing the force of the flushing water.

[0042] Furthermore, in the flush toilet 1 according to this embodiment, a narrowing section 30 is provided upstream of the narrowing section 32, in which the cross-sectional area of ​​the flow path gradually decreases toward the downstream side. This allows flushing water to flow toward the narrowing section 32 while suppressing pressure loss.

[0043] In the flush toilet 1 according to this embodiment, an expanding section 34 is provided downstream of the constricting section 32, in which the cross-sectional area of ​​the flow path gradually expands toward the downstream side. As a result, the flushing water flows along the inner circumferential surface of the expanding section 34 and can be divided into the first rim water channel 24 and the second rim water channel 26.

[0044] Furthermore, in the flush toilet 1 according to this embodiment, in a plan view, the radius of curvature R1 of the inner surface at the point where the common water channel 22 bends into the first rim water channel 24 is set to be larger than the radius of curvature R2 of the inner surface at the point where the common water channel 22 bends into the second rim water channel 26. Therefore, more flushing water can be flowed into the first rim water channel 24 than into the second rim water channel 26.

[0045] In the flush toilet 1 according to this embodiment, in a plan view, the lengths (L1, L2, and L3) of the retraction section 30, the constriction section 32, and the expansion section 34 in the front-rear direction are set to be approximately the same. Therefore, compared to conventional flush toilets, the common water channel 22 directly below the connection port 22a can be filled with water more quickly, and flushing water can be discharged from the first rim outlet 18 and the second rim outlet 20 more quickly.

[0046] Furthermore, in the flush toilet 1 according to this embodiment, the constricted portion 32 is formed by curved surfaces at each of the four corners of the flow path cross-section, so that the flow rate of flushing water discharged from the first rim outlet 18 and the second rim outlet 20 can be kept constant by the constricted portion 32 while suppressing pressure loss.

[0047] In the flush toilet 1 according to this embodiment, a stepped portion 24a that reduces the cross-sectional area of ​​the flow path is formed in the first rim water channel 24, so that the amount of flushing water discharged from the first rim water outlet 18 can be adjusted.

[0048] The present invention is not limited to the embodiments described above, and various modifications and variations are possible within the scope of the technical idea described in the claims. [Explanation of Symbols]

[0049] 1: Flush toilet 2: Toilet bowl 4: Washing water tank 4b: Drain outlet of the cleaning water tank 6: Bowl section 8: Drain trap pipe 10: Waste receiving surface 12: Rim section 18: First rim outlet 20: Second rim outlet 22: Common water conduit 22a: Connection point for the common water conduit 22b: Upper surface of the common water conduit 24: First Rim Waterway 24a: Stepped section 26: Second Rim Waterway 30:Reduction part 30a: Top surface of the reduced section 30b: Bottom surface of the reduced section 32: Aperture section 32a: Top surface of the aperture 32b: Bottom surface of the aperture 32c: Corner of the aperture 34: Enlarged section 34a: Upper surface of the enlarged section 34b: Bottom surface of the enlarged section H1~H4: Vertical width W1~W4: Width R1,R2: radius of curvature

Claims

1. A flush toilet that uses flushing water to wash away waste, A bowl portion comprising a waste receiving surface for receiving waste, and a rim portion formed above the waste receiving surface, A drain trap pipe is connected below this bowl section for discharging waste, A first rim outlet is provided on the rim portion and discharges cleaning water to form a swirling flow, A second rim outlet is provided on the rim portion and discharges cleaning water to form a swirling flow that swirls in the same direction as the cleaning water discharged from the first rim outlet, A common water conduit connected to the washing water supply source, A first rim water channel branches off from the downstream end of this common water channel and connects to the first rim discharge port mentioned above, A second rim water channel branches off from the downstream end of the above common water channel and connects to the above second rim discharge port, It has, A flush toilet, characterized in that the common water channel is provided with a constricted section having the smallest cross-sectional area of ​​the common water channel, and the constricted section is set so that both the width and height of the cross-sectional area of ​​the channel are the smallest among the common water channels.

2. The above-mentioned constricted portion is formed to be inclined downward toward the downstream side, as described in claim 1.

3. A flush toilet according to claim 1 or 2, wherein a narrowing section is provided upstream of the constricted section, the cross-sectional area of ​​the flow path gradually decreases toward the downstream side.

4. A flush toilet according to claim 3, wherein an expanding section is provided downstream of the constricted section, the cross-sectional area of ​​the flow path gradually increases toward the downstream side.

5. The flush toilet according to claim 1, wherein, in a plan view, the radius of curvature of the inner surface at the portion where the common water channel bends into the first rim water channel is set to be greater than the radius of curvature of the inner surface at the portion where the common water channel bends into the second rim water channel.

6. The flush toilet according to claim 4, wherein, in a plan view, the lengths of the retracted portion, the constricted portion, and the enlarged portion in the front-to-back direction are set to be substantially the same.

7. The toilet flushing device according to claim 1, wherein the constricted portion is formed by a curved surface at each of the four corners of the cross-section of the flow path.

8. The flush toilet according to claim 1, wherein a stepped portion is formed in the first rim water channel to reduce the cross-sectional area of ​​the flow path.

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