Water-washable toilet

Abstract

To provide a water closet for avoiding drainage from flowing backwards into a water storage tank when the water level of a bowl part rises even if arranging the water storage tank in a low silhouette fashion.SOLUTION: The syphon jet type water closet according to this invention includes a drain trap pipeline including a riser tube, a down comer, and a crown, a jet water discharge port for discharging washing water to the inlet of the drain trap pipeline, a water storage tank 4 for supplying the washing water to the jet water discharge port with the opening operation of a drain valve 38, a jet water channel 16 connecting the water storage tank to the jet water discharge port so that the washing water in the water storage tank is guided to the jet water discharge port with a head pressure, and a controller for performing water supply operation to the water storage tank and the opening operation of the drain valve. The drain valve includes a valve element, and the valve element is arranged at a position lower than the upper face of the bowl part. The controller executes the water supply operation to the water storage tank and the opening operation of the drain valve so that a tank water level in the water storage tank is located higher than the water level of a reserved water surface W of the bowl part during washing operation.SELECTED DRAWING: Figure 7A

Description

[Technical Field]

[0001] The present invention relates to a flush toilet, and more particularly to a siphon jet type flush toilet. [Background technology]

[0002] Conventionally, siphon jet flush toilets have been known in which water is supplied directly from the water mains to the rim spout, and flush water is directed to the jet spout from a low-height water storage tank using head pressure, as described in Patent Document 1. Also known is a siphon jet flush toilet in which front rim spouting, middle rim spouting, and rear rim spouting are performed consecutively, and jet water spouting is performed during middle rim spouting (sequential control), as described in Patent Document 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5180295 [Patent Document 2] Japanese Patent Application Publication No. 2023-32964 Summary of the Invention [Problem to be solved by the invention]

[0004] In the flush toilet of Patent Document 1 mentioned above, the tank is positioned to have a low silhouette, and furthermore, the jet water is directed into the jet water conduit by the head pressure of the flush water in the tank, so if the water level in the bowl rises due to clogging with waste or the like, wastewater may flow back into the tank. The flush toilet of Patent Document 2 also has the same problem of sewage backflow.

[0005] Therefore, the present invention was made to solve the problems (issues) associated with conventional technology, and aims to provide a flush toilet that will not cause sewage to backflow into the water storage tank when the water level in the bowl rises, even if the water storage tank is positioned with a low silhouette. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a siphon jet flush toilet, comprising: a bowl portion having a waste receiving surface and a rim portion formed along the upper edge of the waste receiving surface; a rim spout that supplies flush water to the bowl portion; a drain trap pipe connected below the bowl portion, the drain trap pipe having an ascending pipe extending upward from below the bowl portion, a descending pipe extending downward from the ascending pipe, a top portion that is located between the ascending pipe and the descending pipe and that defines a water seal position; a jet spout that is located below the bowl portion so as to spout flush water toward the inlet of the drain trap pipe; the drain valve is provided with a valve body that is positioned lower than the top surface of the bowl portion, and the control device supplies water to the water storage tank or opens the drain valve so that the tank water level in the water storage tank is higher than the water level of the water surface in the bowl portion during the flushing operation. According to the present invention configured in this manner, even if waste becomes clogged during the cleaning operation, the control device will supply water to the water storage tank or open the drain valve so that the water level in the water storage tank is always higher than the water level of the water surface in the bowl section, thereby preventing wastewater from flowing back from the bowl section side to the tank side.

[0007] In the present invention, preferably, when the water level in the bowl portion rises, the control device opens the drain valve so that the flow rate of flush water discharged from the water storage tank is reduced. According to the present invention configured in this manner, if the water level in the bowl section rises due to clogging with waste or the like, the drain valve is opened to reduce the flow rate of cleaning water discharged from the water storage tank, making it difficult for the water level in the water storage tank to drop, and the water level in the tank becomes higher than the water level in the bowl section, thereby preventing backflow.

[0008] In the present invention, the instantaneous flow rate of flush water drained from the water storage tank is preferably reduced by setting the time for which the drain valve is pulled up to a predetermined fixed value. According to the present invention configured in this manner, by setting the lifting time of the drain valve to a predetermined fixed value, when the difference in water level between the bowl section and the water storage tank becomes small, the instantaneous flow rate of cleaning water drained from the water storage tank becomes lower, making it less likely for the water level in the water storage tank to drop, and preventing the water level in the water storage tank from becoming higher than the water level in the bowl section and causing sewage to flow back from the bowl section into the water storage tank.

[0009] In the present invention, preferably, when the water level in the bowl portion rises above the normal state, the time for lifting the drain valve is shortened to a time shorter than that in the normal state. According to the present invention configured in this manner, when the water level in the bowl section rises above normal, the time for which the drain valve is raised is shortened to a time shorter than normal, thereby reducing the amount of flushing water discharged from the water storage tank. This makes it difficult for the water level in the water storage tank to drop, and prevents the water level in the water storage tank from rising above the water level in the bowl section and causing sewage to flow back from the bowl section into the water storage tank.

[0010] In the present invention, the specific gravity of the drain valve is preferably in the range of 1.2 to 1.4. According to the present invention configured in this manner, the specific gravity of the drain valve is in the range of 1.2 to 1.4, which is greater than the specific gravity of water, which is 1. Therefore, even if the water level in the bowl section rises and the water level in the tank becomes close to equilibrium with the water level in the bowl section, the drain valve will close under its own weight, preventing sewage from flowing back from the bowl section into the water storage tank.

[0011] In the present invention, the flush water level in the water storage tank during standby is preferably set above the upper surface of the bowl portion. According to the present invention configured in this manner, the level of the flushing water in the water storage tank during standby is set above the top surface of the bowl section, so that the water level in the bowl section during standby will never be higher than the level of the flushing water in the water storage tank, thereby preventing backflow.

[0012] In the present invention, preferably, even when the next cleaning operation is performed when there is a blockage of filth, the control device performs the water supply operation to the water storage tank and / or the opening operation of the drain valve so that the level of cleaning water in the water storage tank is higher than the water level of the water surface in the bowl section. According to the present invention configured in this manner, even when the next flushing operation is performed when there is a blockage of sewage, the control device will supply water to the water storage tank and / or open the drain valve so that the level of the flushing water in the water storage tank is always higher than the water level of the water surface in the bowl section, thereby preventing sewage from flowing back from the bowl section into the water storage tank.

[0013] In the present invention, preferably, even when rim water discharge is performed before tank water supply, the control device performs water supply operations to the water storage tank and / or opens the drain valve so that the flush water level in the water storage tank is higher than the water level of the water surface in the bowl section. According to the present invention configured in this manner, even when rim water discharge is performed before tank water supply, the control device performs water supply operations to the water storage tank and / or opens the drain valve so that the level of flush water in the water storage tank is always higher than the water level of the water surface in the bowl section, thereby preventing sewage from flowing back from the bowl section into the water storage tank.

[0014] In the present invention, preferably, after flushing operation, water is supplied to the water storage tank to bring the flush water level to a predetermined level, and then flush water is supplied to the bowl section by the rim spout to bring the pooled water level to a predetermined level. According to the present invention configured in this manner, after the flushing operation, the control device supplies water to the water storage tank to bring the flushing water level to a predetermined level, and then the rim discharges flushing water to the bowl section to bring the water level to a predetermined level, thereby preventing sewage from flowing back from the bowl side into the water storage tank. [Effects of the Invention]

[0015] With the siphon jet flush toilet of the present invention, even if the storage tank is positioned with a low silhouette, wastewater will not backflow into the storage tank when the water level in the bowl rises. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a plan view showing a flush toilet according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a side cross-sectional view taken along line II-II in FIG. [Figure 3] 10 is a time chart showing "rim spouting," "tank water supply," "jet spouting," and "tank water level" in a flush toilet according to an embodiment of the present invention. [Figure 4A] 10 is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet spouting" during a large flush of a flush toilet according to an embodiment of the present invention. [Figure 4B]10 is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet spouting" in a small-flush mode of a flush toilet according to an embodiment of the present invention. [Figure 5A] A diagram showing the instantaneous flow rate of flush water discharged from the rim spout during a large flush of a flush toilet according to an embodiment of the present invention, the instantaneous flow rate of flush water discharged from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe. [Figure 5B] This is a diagram showing the instantaneous flow rate of flush water discharged from the rim spout during a small flush of a flush toilet according to an embodiment of the present invention, the instantaneous flow rate of flush water discharged from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe. [Figure 6A] FIG. 10 is a side cross-sectional view showing the water level difference ΔH1 between the stop water level WL0 and the dead water level WL0 of flush water in the storage tank when the flush toilet is on standby according to an embodiment of the present invention. [Figure 6B] FIG. 10 is a cross-sectional side view showing the water level difference ΔH2 between the dead water level DWL of flush water in the storage tank and the pooled water surface W when the DWL is reached in a flush toilet according to an embodiment of the present invention. [Figure 6C] FIG. 10 is a cross-sectional side view showing the water level difference ΔH3 between the still water level WL0 and dead water level DWL of flush water in the storage tank during tank water supply in a flush toilet according to an embodiment of the present invention. [Figure 7A] FIG. 10 is a cross-sectional side view showing the water level difference ΔH4 between the stopped water level WL0 of flush water in the storage tank and the pooled water surface W when the flush toilet according to an embodiment of the present invention is on standby in the event of a clogged toilet. [Figure 7B] FIG. 10 is a cross-sectional side view showing the water level difference ΔH5 between the dead water level DWL of flush water in the storage tank and the pooled water surface W when the DWL is reached during a clogged flush toilet according to an embodiment of the present invention. [Figure 7C] FIG. 10 is a cross-sectional side view showing the water level difference ΔH6 between the water stop level WL0 of flush water in the storage tank and the water surface W when water is being supplied from the tank when the flush toilet according to an embodiment of the present invention is clogged. [Figure 8] FIG. 2 is a block diagram showing the control content by a controller of a flush toilet according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] A flush toilet according to an embodiment of the present invention will now be described with reference to the drawings. First, the basic structure of a flush toilet according to this embodiment will be explained using Figures 1 and 2. Figure 1 is a plan view showing a flush toilet according to an embodiment of the present invention, and Figure 2 is a side cross-sectional view taken along line II-II in Figure 1.

[0018] As shown in Figures 1 and 2, the flush toilet 1 according to this embodiment is a siphon jet type flush toilet. This flush toilet 1 comprises a ceramic toilet body 2, a resin toilet seat and toilet lid (not shown) placed on the top surface of the toilet body 2, and a water storage tank 4 placed at the upper rear of the toilet body 2 and covered by a resin cover (not shown).

[0019] The toilet body 2 is formed with a bowl portion 6 for receiving waste, a drain trap pipe 8 provided at the bottom of the bowl portion 6 for discharging waste by siphon action, a rim spout 10 for rim water discharge, a rim water conduit 12 for guiding flushing water to the rim spout 10, a jet spout 14 for jet water discharge, and a jet water conduit 16 for guiding flushing water to the jet spout 14.

[0020] Bowl portion 6 has a bowl-shaped waste receiving surface 18, a rim portion 20 formed along the upper edge of bowl portion 6, and a shelf portion 21 formed between waste receiving surface 18 and rim portion 20. Bowl portion 6 also has a pot portion 22 formed in the area below waste receiving surface 18 and connected to drain trap pipe line 16. A water-retaining surface (sealing surface) W is formed inside pot portion 22.

[0021] The drain trap pipeline 8 has an inlet 8a, an ascending pipeline 8b extending upward from the inlet 8a, a descending pipeline 8c extending downward from the ascending pipeline 8b, and a top 8d located between the descending pipeline 8c and the ascending pipeline 8b and determining the sealing water level of the sealing surface W. Here, the lower end of the descending pipe 8c of the drain trap pipe 8 is connected to a drain pipe (not shown) via a drain socket (not shown).

[0022] When viewing the toilet body 2 from the front, the rim spout 10 is formed on the left rear side of the rim portion 20. The rim spout 10 spouts flush water forward, and this flush water swirls around the inner circumferential surface of the rim portion 20 and the shelf surface of the shelf portion 21 before flowing down to the waste receiving surface 18, cleaning it.

[0023] The rim conduit 12 is formed in a tapered shape, with the flow path cross section gradually becoming smaller towards the rim spout 10. A water supply hose 23 that is directly connected to the water supply is connected to the upstream side of the rim conduit 12. Flush water is supplied to the rim conduit 12 from the water supply, and is discharged from the rim spout 10 by the water supply pressure of the water supply.

[0024] Jet water spout 14 is formed in the bottom of bowl portion 6. Jet water spout 14 is positioned opposite inlet 8a of drain trap pipe 8 and is directed toward inlet 8a of drain trap pipe 8. Jet water spout 14 spouts flush water toward inlet 8a of drain trap pipe 8, and this flush water flows into drain trap pipe 8, activating the siphon action.

[0025] The jet water conduit 16 comprises an upstream flow path 16a extending forward from the water storage tank 4, a curved flow path 16b bending from this upstream flow path, and a downstream flow path 16c extending rearward from this curved flow path and connecting to the jet water spouting port 14. Flush water is supplied to the jet water conduit 16 from the water storage tank 4, and the flush water is spouted from the jet water spouting port 14 due to the head pressure of the flush water.

[0026] The water storage tank 4 is a gravity-fed tank that stores flush water to be used for jet spouting and supplies it to the jet spout 14. Flush water is stored in the water storage tank 4 up to the stop water level (WL0), and flush water from the stop water level to the dead water level (DWL) is used for jet spouting. The water storage tank 4 is a small resin tank. The lower part of the water storage tank 4 (the valve body of the drain valve 38) and the dead water level (DWL) are positioned below the top surface of the rim part 20 of the toilet body 2, and above the top 8d of the drain trap pipe 8. This makes the flush toilet 1 a low-silhouette type toilet.

[0027] Provided within the water storage tank 4 are a water supply device 24 that supplies flush water into the water storage tank 4, a drainage device 26 that supplies or stops the flush water stored in the water storage tank 4 to the jet water conduit 16, and a float switch 28 that detects when the flush water level in the water storage tank 4 has reached the stop water level (WL0). Also provided outside the water storage tank 4 are a controller 52 (see Figure 8) that controls the water supply device 24 and drainage device 26 to operate or stop based on an operation signal from the user, and an operation unit 50 (see Figure 8) that sends out an operation signal in response to operation by the user.

[0028] The water supply device 24 comprises a constant flow valve (not shown) connected to the water supply, a rim-side solenoid valve 30 that supplies or stops the flow of flush water to the rim spout 10, and a tank-side solenoid valve 34 that supplies or stops the flow of flush water to a tank water supply port 32 located inside the water storage tank 4. The rim-side solenoid valve 30 and tank-side solenoid valve 34 are designed to be driven by commands from the controller 52 based on operation signals from the user and water level detection signals from the float switch 28.

[0029] The drainage device 26 comprises an overflow pipe 36 that drains overflowing water from the water storage tank 4 into the toilet body, a drain valve 38 fixed to the lower end of the overflow pipe 36, and a toilet flushing unit 40 that opens and closes the drain valve 38 by moving the overflow pipe 36 up and down using an electric drive force. The overflow pipe 36 has open upper and lower ends so that overflowing water from the water storage tank 4 is discharged into the jet water conduit 16. A guide member 42 that guides the up and down movement of the drain valve 38 is attached to the periphery of the drain outlet 4a of the water storage tank 4. The toilet flushing unit 40 is driven by commands from a controller 52 based on an operation signal from the user.

[0030] The controller 52 is electrically connected to the operation unit 50, float switch 28, rim-side solenoid valve 30, tank-side solenoid valve 34, and toilet flushing unit 40, and is capable of sending and receiving various signals (see Figure 8). The controller 52 receives a flush start signal for a large flush or small flush from the operation unit 50, and drives or stops the rim-side solenoid valve 30, tank-side solenoid valve 34, and toilet flushing unit 40 based on a pre-stored flush sequence.

[0031] Next, we will explain "rim water spouting," "tank water supply," "jet water spouting," and "tank water level" in a flush toilet 1 according to this embodiment with reference to Figure 3. Figure 3 is a time chart showing "rim water spouting," "tank water supply," "jet water spouting," and "tank water level" in a flush toilet according to an embodiment of the present invention.

[0032] Here, "rim water discharge" refers to the discharge of flush water from the rim water discharge port 10, "tank water supply" refers to the supply of water to the water storage tank 4, "jet water discharge" refers to the discharge of flush water from the jet water discharge port 14, and "tank water level" refers to the level of flush water in the water storage tank 4.

[0033] As shown in Figure 3, during a large flush of the flush toilet 1, first, after a standby state at time t0, when the user operates the operating unit 50, the rim-side solenoid valve 38 turns ON at time t1, commencing rim spouting, in which water is supplied to the rim water conduit 12 and flush water is spouted from the rim spout 10. This rim spouting continues until time t5.

[0034] Next, at time t2, the drain valve 38 is opened and turned ON, and jet spouting begins, in which flush water in the water storage tank 4 passes through the jet water conduit 16 and is spouted from the jet spouting port 14. This jet spouting ends at time t4. While jet water spouting is taking place from time t2 to time t4, rim spouting is also taking place at the same time.

[0035] 3, for convenience, the rim spouting from time t1 when rim water spouting begins to time t2 when jet water spouting begins will be referred to as "front rim water spouting," the rim water spouting from time t2 when jet water spouting is performed to time t4 will be referred to as "middle rim water spouting," and the rim water spouting from time t4 when jet water spouting ends to time t5 when rim water spouting ends will be referred to as "rear rim water spouting." Also, as mentioned above, "jet water spouting" is performed from time t2 to time t4.

[0036] Next, as shown in Figure 3, at time t2 when jet water spouting began, the level of flush water in the water storage tank 4 was at the still water level so float switch 28 was ON, but at the subsequent time t3 the level of flush water in the water storage tank 4 drops below the still water level so float switch 28 turns OFF. This OFF state of float switch 28 continues until time t7.

[0037] Also, at time t6, tank-side solenoid valve 34 is opened and turned ON, and tank water supply to the water storage tank 4 begins, finishing at time t8. As this tank water supply begins at time t6, the flush water level in the water storage tank 4 rises, which causes float switch 28 to return to ON at time t7 as the flush water level in the water storage tank 4 rises to the stop water level, entering a full water state.

[0038] The large flush has been explained using Figure 3, but the time chart in Figure 3 also applies to the small flush. Note that, as will be described later, the large flush and small flush have different water discharge times and volumes.

[0039] Next, the water spouting times and water spouting volumes of rim spouting and jet water spouting in the large flush and small flush will be explained using Figures 4A and 4B. Figure 4A is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet water spouting" in the large flush of a flush toilet according to an embodiment of the present invention, and Figure 4B is a table showing the water spouting times and water spouting volumes of "front rim spouting," "middle rim spouting," "rear rim spouting," and "jet water spouting" in the small flush of a flush toilet according to an embodiment of the present invention.

[0040] As shown in Figure 4A, in the case of large flush, the front rim water spouting time is 1.9 seconds (s) and the water spouting volume is 0.41 liters (L), the middle rim water spouting time is 2.4 seconds (s) and the water spouting volume is 0.52 liters (L), and the rear rim water spouting time is 6.1 seconds (s) and the water spouting volume is 1.32 liters (L). In addition, the jet water spouting time is 2.4 seconds (s) and the water spouting volume is 2.31 liters (L).

[0041] As is clear from Figure 4A, in the case of large flush, the water spouting time of the front rim water spout (1.9 seconds) is shorter than the water spouting time of the rear rim water spout (6.1 seconds). Furthermore, the total water spouting time of the front rim water spout and the middle rim water spout (1.9 seconds + 2.4 seconds) is shorter than the water spouting time of the rear rim water spout (6.1 seconds).

[0042] Similarly, as shown in Figure 4B, for a small flush, the front rim water spouting time is 1.4 seconds (s) and the water spouting volume is 0.31 liters (L), the middle rim water spouting time is 1.7 seconds (s) and the water spouting volume is 0.37 liters (L), and the rear rim water spouting time is 7.6 seconds (s) and the water spouting volume is 1.64 liters (L). Also, the jet water spouting time is 1.7 seconds (s) and the water spouting volume is 1.50 liters (L).

[0043] As is clear from Figure 4A, in the case of the small flush, as in the case of the large flush described above, the water spouting time of the front rim water spout (1.4 seconds) is shorter than the water spouting time of the rear rim water spout (7.6 seconds). Furthermore, the total water spouting time of the front rim water spout and the middle rim water spout (1.4 seconds + 1.7 seconds) is shorter than the water spouting time of the rear rim water spout (7.6 seconds).

[0044] Next, the instantaneous flow rate of flush water spouted from the rim spout during the large flush and small flush, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe in a flush toilet according to an embodiment of the present invention will be explained with reference to Figures 5A and 5B. Figure 5A is a diagram showing the instantaneous flow rate of flush water spouted from the rim spout during the large flush of a flush toilet according to an embodiment of the present invention, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe, and Figure 5B is a diagram showing the instantaneous flow rate of flush water spouted from the rim spout, the instantaneous flow rate of flush water spouted from the jet spout, and the instantaneous flow rate of flush water flowing into the inlet of the drain trap pipe in a small flush of a flush toilet according to an embodiment of the present invention.

[0045] In Figures 5A and 5B, the dashed line indicates the instantaneous flow rate of flush water discharged from the jet water outlet 14, the dotted line indicates the instantaneous flow rate of flush water discharged from the rim water outlet 10, and the solid line indicates the instantaneous flow rate of flush water flowing into the inlet 8a of the drain trap pipe 8.

[0046] As shown in Figure 5A, during a large flush, at time t2 the drain valve 38 opens and flush water in the water storage tank 4 passes through the jet water conduit 17 and is discharged from the jet spouting port 14. The instantaneous flow rate of the jet water spouting, shown by the dashed line, increases suddenly immediately after it starts and then remains approximately constant. At time t4 the drain valve 48 closes, causing the instantaneous flow rate of the jet water spouting to decrease as well.

[0047] The rim water spouting indicated by the dashed dotted line has a constant instantaneous flow rate and is also performed between time t2 and time t4 when jet water spouting is being performed. Furthermore, flush water discharged by the rear rim discharge during the previous flush remains in the bowl portion 6 as pooled water. Therefore, between time t2 and time t4, the flush water from the rim spout and the accumulated water remaining in the bowl section 6 due to the post-rim spout from the previous flush combine with the flush water from the jet spout, and a large flow of flush water flows into the inlet 8a of the drain trap pipe 8, as shown by the solid line.

[0048] As a result, in this embodiment, even if flush water is supplied to the jet water conduit 16 by the head pressure of the flush water in the low-profile water storage tank (although siphon action is unlikely to occur with this jet water spout alone), the flush water and accumulated water from the rim spout also flow into the inlet 8a of the drain trap pipe 8, so that a powerful siphon action can be used to reliably discharge waste.

[0049] After the drain valve 38 closes at time t4, the instantaneous flow rate of the jet water spouting decreases, but the rim water spouting continues at the same instantaneous flow rate. As a result, the instantaneous flow rate of flush water from the jet water spouting and rim water spouting decreases, but this allows the siphon action to continue. In this way, a strong siphon action can be generated without increasing the amount of water stored in the water storage tank 4, and furthermore, this siphon action can be continued, so that water conservation can be achieved.

[0050] Next, as shown in Figure 5B, in a small flush, at time t2 the drain valve 38 opens and flush water in the water storage tank 4 passes through the jet water conduit 17 and is spouted from the jet water spouting port 14. The instantaneous flow rate of the jet water spouting, shown by the dashed line, increases suddenly immediately after it starts and then remains approximately constant. At time t4 the drain valve 48 closes, which causes the instantaneous flow rate of the jet water spouting to also decrease.

[0051] The rim water spouting indicated by the dashed dotted line has a constant instantaneous flow rate and is also performed between time t2 and time t4 when jet water spouting is being performed. Furthermore, flush water discharged by the rear rim discharge during the previous flush remains in the bowl portion 6 as pooled water. For this reason, between time t2 and time t4, flush water from the jet spouting and rim spouting flows into the inlet 8a of the drain trap pipe 8. However, after time t4, the flush water from the rim spouting and the pooled water remaining in the bowl section 6 combine with the flush water from the jet spouting, and a large flow rate of flush water flows into the inlet 8a of the drain trap pipe 8, as shown by the solid line.

[0052] As a result, in this embodiment, even in the case of a small flush, even if flush water is supplied to the jet water conduit 16 by the head pressure of the flush water in the low-silhouette water storage tank (although siphon action is unlikely to occur with this jet water spout alone), the flush water and accumulated water from the rim spout also flow into the inlet 8a of the drain trap pipe 8, so that a strong siphon action can be used to reliably discharge waste.

[0053] Furthermore, after a strong siphoning action occurs, the instantaneous flow rate of flush water from the jet spouting and rim spouting decreases, but this allows the siphoning action to continue. In this way, even in the case of a small flush, a strong siphon action can be generated without increasing the amount of water stored in the water storage tank 4, and this siphon action can be continued, thereby achieving water conservation.

[0054] Next, the water level difference between the flush water level in the storage tank and the pooled water surface when a flush toilet 1 according to this embodiment is normal (when not clogged) will be explained using Figures 6A to 6C. Figure 6A is a side cross-sectional view showing the water level difference ΔH1 between the dead water level WL0 and dead water level DWL of the flush water in the storage tank when a flush toilet according to an embodiment of the present invention is on standby, Figure 6B is a side cross-sectional view showing the water level difference ΔH3 between the dead water level DWL of the flush water in the storage tank when DWL is reached and the pooled water surface W, and Figure 6C is a side cross-sectional view showing the water level difference ΔH3 between the dead water level WL0 and dead water level DWL of the flush water in the storage tank when water is being supplied to the tank.

[0055] First, as shown in Figure 6A, during standby, there is a water level difference of ΔH1 between the still water level WL0 and the dead water level DWL in the water storage tank 4, and the dead water level DWL is higher than the water level of the pooled water surface W. Therefore, even if the drain valve 38 is opened after standby, the pooled water at the pooled water surface W will not flow back into the water storage tank 4.

[0056] Next, as shown in Figure 6B, when DWL is reached, the pooled water level W is higher than during standby. However, there is a water level difference of ΔH2 (<ΔH1) between the dead water level DWL in the water storage tank 4 and the pooled water level W. Therefore, even if the drain valve 38 is open and the water storage tank 4 and the pooled water level W are in communication before and after DWL is reached, there is a sufficient water level difference between the dead water level DWL and the pooled water level W as shown in Figure 6B, so the pooled water at the pooled water level W will not flow back into the water storage tank 4.

[0057] 6C, when water is being supplied to the tank, it is the same as during standby as described above, and there is a water level difference of ΔH3 (=ΔH1) between the still water level WL0 and the dead water level DWL of the water storage tank 4, and the dead water level DWL is higher than the water level of the pooled water surface W. Therefore, even if the drain valve 38 is opened in this state and the pooled water surface W and the water storage tank are connected, the pooled water at the pooled water surface W will not flow back into the water storage tank 4.

[0058] Next, the difference in level between the flush water level in the storage tank and the pooled water surface when a flush toilet 1 according to this embodiment is clogged will be explained using Figures 7A to 7C. Figure 7A is a side cross-sectional view showing the water level difference ΔH4 between the stopped water level WL0 of the flush water in the storage tank and the pooled water surface W when a flush toilet according to an embodiment of the present invention is on standby when clogged, Figure 7B is a side cross-sectional view showing the water level difference ΔH5 between the dead water level DWL of the flush water in the storage tank when DWL is reached and the pooled water surface W, and Figure 7C is a side cross-sectional view showing the water level difference ΔH6 between the stopped water level WL0 of the flush water in the storage tank and the pooled water surface W when water is being supplied to the tank.

[0059] First, we will explain how to detect when the pooled water level W has risen above its normal position (sealed water position). When the toilet is clogged and the pooled water level W is higher than its normal position, the head pressure between the flush water level in the storage tank 4 and the pooled water level is reduced, and the amount of flush water discharged from the storage tank 4 during flushing is less than normal, so the water level in the storage tank 4 is higher than the normal dead water level (DWL). When water supply to the storage tank 4 is started from this state, the time it takes to reach the dead water level at this higher position and the stop water level (WL0) detected by the float switch 28 becomes shorter, resulting in a discrepancy with the normal water supply time. This discrepancy in the water supply time (shorter water supply time) makes it possible to detect the rise in the pooled water level W.

[0060] First, as shown in Figure 7A, when the toilet is clogged, the water level W is higher than its normal position during standby. Therefore, the water level difference between the water stop level WL0 in the water tank 4 and the water level W is ΔH4, which is smaller than under normal conditions. However, because the water stop level WL0 is above the top surface of the bowl, the water at the water level W will not flow back into the water tank 4 even if the drain valve 38 is opened in this state.

[0061] Next, as shown in Figure 7B, when the dead water level (DWL) is reached, the pooled water level W has risen further than during standby as described above. At this time, as described above, the dead water level is higher than the normal dead water level. Therefore, the water level difference between the dead water level DWL of the flush water in the storage tank 4 and the pooled water level W is ΔH5, which is a small value, and the two are in equilibrium. However, as will be described later, since the specific gravity of the drain valve 13 is approximately 1.3, even when equilibrium is reached, the drain valve 13 closes under its own weight, so the pooled water at the pooled water level W does not flow back into the storage tank 4.

[0062] 7C, even when water is being supplied to the tank, the water level W rises considerably. However, as a result of the water supply to the tank, the water level in the water storage tank 4 is at the stop water level WL0, which is higher than the top surface of the bowl. Therefore, even if the drain valve 38 is opened in this state, the water at the water level W will not flow back into the water storage tank 4.

[0063] Next, the control details for supplying water to and draining water from the water storage tank in a flush toilet according to this embodiment will be explained using Figure 8. Figure 8 is a block diagram showing the control details by the controller of the flush toilet according to this embodiment.

[0064] As shown in Figure 8, when the operating unit 52 is operated by the user, an operation signal is sent to the controller 52. If the operation signal is related to starting or stopping rim water spouting, the rim-side solenoid valve 30 is operated to open or close, and rim water spouting is started or stopped. If the operation signal is related to tank water supply to the water storage tank, the tank side electromagnetic valve 34 is opened or closed, and water supply to the water storage tank 4 is started or stopped. If the operation signal is related to the opening or closing of the drain valve 38, the toilet flushing unit 40 opens or closes the drain valve 38.

[0065] Next, the effects of the flush toilet according to this embodiment will be described. First, in the flush toilet 1 of this embodiment, during flushing operation, the controller 52 supplies water to the water storage tank 4 using the tank-side solenoid valve 34, or opens the drain valve 38 using the toilet flushing unit 40, so that the tank water level in the water storage tank 4 is higher than the water level of the water surface W in the bowl section 6. As a result, with the flush toilet 1 of this embodiment, even if waste becomes clogged in the drain trap pipe 8 during the flushing operation and the tank water level becomes equilibrium with the water level of the rising water surface W, it is possible to prevent wastewater from flowing back from the bowl portion 6 into the water storage tank 4.

[0066] Secondly, in the flush toilet 1 according to this embodiment, if the water level in the bowl section 6 rises due to clogging with waste or the like, the controller 52 reduces the flow rate of flush water discharged from the water storage tank 4, that is, by shortening the open time of the drain valve 38, making it difficult for the water level in the water storage tank 4 to drop, and making the water level in the water storage tank 4 higher than the water level in the bowl section 6, thereby preventing backflow.

[0067] Thirdly, in the flush toilet 1 according to this embodiment, by setting the time for which the drain valve 38 is raised to a predetermined fixed value, when the difference between the water level in the bowl section 6 and the water level in the water storage tank 4 becomes small, the instantaneous flow rate of flush water drained from the water storage tank 4 decreases, making it difficult for the water level in the water storage tank 4 to drop, and preventing the water level in the water storage tank 4 from rising higher than the water level in the bowl section 6 and causing sewage to flow back from the bowl section 6 into the water storage tank 4.

[0068] Fourth, in the flush toilet 1 according to this embodiment, when the water level in the bowl section 6 rises above normal, the amount of time the drain valve 38 is raised is shortened to a time shorter than normal, reducing the amount of flush water discharged from the storage tank. This makes it difficult for the water level in the storage tank 4 to drop, and prevents the water level in the storage tank 4 from rising above the water level in the bowl section 6 and causing sewage to flow back into the storage tank 4 from the bowl section 6.

[0069] Fifth, in the flush toilet 1 according to this embodiment, the specific gravity of the drain valve 38 is set to approximately 1.3. It is also preferable that the specific gravity of the drain valve 38 be in the range of 1.2 to 1.4. In this way, by setting the specific gravity of the drain valve to the range of 1.2 to 1.4 (including 1.3), even if the water level in the bowl section 6 rises and the water level in the water storage tank 4 becomes close to equilibrium with the water level in the bowl section 6, the drain valve 38 will close under its own weight, preventing sewage from flowing back from the bowl section 6 into the water storage tank 4.

[0070] Sixth, in the flush toilet 1 according to this embodiment, the flush water level in the water storage tank during standby is set above the top surface of the bowl section 6, so the water level in the bowl section during standby will never be higher than the flush water level in the water storage tank, preventing backflow.

[0071] Seventh, with the flush toilet 1 of this embodiment, even when the next flushing operation is performed after a blockage of waste has occurred, the controller 52 performs a water supply operation using the rim-side solenoid valve 30 of the water storage tank 4 and / or an opening operation using the tank-side solenoid valve 34 of the drain valve 38 so that the flush water level in the water storage tank 4 is always higher than the water level of the water surface W in the bowl section 6, thereby preventing wastewater from flowing back from the bowl section 6 into the water storage tank 4.

[0072] Eighth, with the flush toilet 1 of this embodiment, even when rim discharging is performed before tank water supply, the controller 52 performs a water supply operation to the water storage tank 4 using the rim-side solenoid valve 30 and / or an opening operation of the tank-side solenoid valve 34 of the drain valve 38 so that the flush water level in the water storage tank 4 is always higher than the water level of the water surface W in the bowl section 6, thereby preventing sewage from flowing back from the bowl section 6 into the water storage tank 4.

[0073] Ninth, in the flush toilet 1 of this embodiment, after the flushing operation, the controller 52 operates the tank-side solenoid valve 34 to supply water to the storage tank 4 and set the water level to WL0, and then the rim discharge supplies flush water to the bowl section 6 and sets the water level W to a predetermined level, thereby preventing sewage from flowing back from the bowl section 6 into the storage tank 4. [Explanation of symbols]

[0074] 1 flush toilet 2 Toilet body 4. Water tank 6 Bowl section 8 Drain trap pipe 8a entrance 8b Ascending pipe 8c descending pipe 8d top 10 Rim Spout 14 Jet outlet 16 Jet Waterway 18 Waste receiving surface 20 Rim 24 Water supply equipment 26 Drainage system 28 Float switch 30 Rim side solenoid valve 32 Tank water inlet 34 Tank side solenoid valve 36 Overflow pipe 38 Drain valve 40 Toilet flushing unit 50 Control section 52 Controller W Water storage surface (water sealing surface) WL0 Water stop level DWL dead water level

Claims

1. A siphon jet flush toilet, a bowl portion having a waste receiving surface and a rim portion formed along an upper edge of the waste receiving surface; a rim spout that supplies flushing water to the bowl portion; a drain trap pipe connected to the lower part of the bowl portion, the drain trap pipe having an ascending pipe extending upward from the lower part of the bowl portion, a descending pipe extending downward from the ascending pipe, and a top portion positioned between the ascending pipe and the descending pipe and defining a water seal position; a jet spout disposed below the bowl portion so as to spout flush water toward the inlet of the drain trap pipe; a water storage tank for storing flush water, the water storage tank supplying the stored flush water to the jet water outlet by opening a drain valve; a jet water conduit that connects the water storage tank and the jet water outlet, and that guides flush water in the water storage tank to the jet water outlet by head pressure; a control unit that supplies water to the water storage tank and opens a drain valve, The drain valve includes a valve body, and the valve body is positioned lower than the upper surface of the bowl portion. A flush toilet, wherein the drain valve has a specific gravity of 1.2 or more.

2. A siphon jet flush toilet, a bowl portion having a waste receiving surface and a rim portion formed along an upper edge of the waste receiving surface; a rim spout that supplies flushing water to the bowl portion; a drain trap pipe connected to the lower part of the bowl portion, the drain trap pipe having an ascending pipe extending upward from the lower part of the bowl portion, a descending pipe extending downward from the ascending pipe, and a top portion positioned between the ascending pipe and the descending pipe and defining a water seal position; a jet spout disposed below the bowl portion so as to spout flush water toward the inlet of the drain trap pipe; a water storage tank for storing flush water, the water storage tank supplying the stored flush water to the jet water outlet by opening a drain valve; a jet water conduit that connects the water storage tank and the jet water outlet, and that guides flush water in the water storage tank to the jet water outlet by head pressure; a water level detection unit that detects the tank water level in the water storage tank; a control unit that supplies water to the water storage tank and opens a drain valve, The drain valve includes a valve body, and the valve body is positioned lower than the upper surface of the bowl portion. In this flush toilet, the control unit supplies water to the water storage tank based on the tank water level detected by the water level detection unit so that the tank water level is higher than the water level of the water surface in the bowl during the flushing operation.

3. 3. A flush toilet according to claim 2, wherein the instantaneous flow rate of flush water drained from the water storage tank is reduced by setting the time for which the drain valve is raised to a predetermined fixed value.

4. 3. The flush toilet according to claim 1 or 2, wherein the flush water level in the storage tank during standby is set above the upper surface of the bowl portion.

5. A flush toilet as described in claim 1, wherein the control unit supplies water to the water storage tank and / or opens the drain valve so that the flush water level in the water storage tank is higher than the water level in the bowl section when the next flushing operation is performed after a blockage of waste has occurred.

6. A flush toilet as claimed in claim 1 or 2, wherein the control unit performs a water supply operation to the water storage tank and / or an opening operation of the drain valve so that the flush water level in the water storage tank is higher than the water level of the water surface in the bowl section, even when rim water discharge is performed before tank water supply.

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