JPH055258Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vacuum pump that is small and requires a small installation space.

[Prior Art] A vacuum pump used as a negative pressure source for a vehicle equipped with an internal combustion engine has a pump chamber defined by a diaphragm inside a housing, as disclosed in, for example, Japanese Utility Model Application Publication No. 59-172238. The rod connected to the diaphragm is biased into engagement with the cam of the camshaft by the force of a spring. While the diaphragm is reciprocated by the cam, the air in the pump chamber is discharged to the outside through the first check valve, and then, while the diaphragm is reciprocated by the spring, the air in the negative pressure tank is discharged to the second pump chamber. It is sucked through the check valve. thus,
Negative pressure tank becomes negative pressure.

[Problems to be solved by the invention] In such conventional vacuum pumps, a diaphragm or a piston in place of the diaphragm is driven by a cam, so it is necessary to reciprocate the diaphragm or piston between the cam and the diaphragm. Rod is required. This makes the overall shape of the pump very large, and if the rod is driven by the engine's crankshaft, a large amount of space is required for installation.

Therefore, the purpose of this invention is to have a small overall shape.
It is an object of the present invention to provide a vacuum pump which is particularly flat and which saves mounting space so that it can be mounted, for example, on a head cover.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention includes a cup-shaped cylinder attached to an immovable piston equipped with a pair of check valves on the end walls that allow flow in opposite directions. They fit together to form a pump chamber, and the end wall of the cylinder is urged into engagement with the cam of the camshaft by a spring.

[Operation] A movable cup-shaped cylinder 12 is fitted onto the immovable piston 2, and a pump chamber 14 is formed between the two. When the cylinder is reciprocated, the air in the pump chamber is discharged to the outside by the cam of the camshaft that engages with the end wall of the cylinder, and when the cylinder is reciprocated by the force of the spring, a negative pressure tank is discharged into the pump chamber. Air is sucked in. Since the cylinder is reciprocated directly by the cam, the shape of the vacuum pump as a whole becomes flat, and it is mounted so that it can be placed inside the head cover of an internal combustion engine, for example, and driven by the camshaft that drives the intake and exhaust valves. Space is greatly saved.

[Embodiment of the invention] As shown in FIG. 1, a cylinder head 21 connected to the top end of a cylinder body of an internal combustion engine is equipped with an intake port 22 and an exhaust port (not shown), and has a cylinder head inside. Cooling water chamber 2
4 is provided, and a valve operating mechanism for driving intake/exhaust valves (not shown) is also attached. A camshaft 23 is supported at the upper end of the cylinder head 21, and the upper side of the camshaft 23 is covered by a head cover 19.

In the illustrated embodiment, a head cover 19 includes a mounting wall 9, with an inlet 10 formed on one side thereof and an outlet 7 formed on the other side thereof. A cup-shaped piston 2 is fixed inside the mounting wall 9. Inside this piston 2, a chamber connected to an inlet 10 and a chamber connected to an outlet 7 are partitioned by a partition wall 8. Further, a check valve 15 for opening and closing the passage 3 is provided on the end wall of the piston 2;
A check valve 5 that opens and closes the passage 17 is provided. This check valve 5 is mushroom-shaped and made of soft rubber.

A cup-shaped cylinder 12 is fitted onto the piston 2, thereby defining a pump chamber 14. A spring 20 is interposed between the end flange 2a of the piston 2 and the flange 18a of the end wall 18 of the cylinder 12.
8 is forcefully engaged with the cam 16 of the camshaft 23.

A rod is connected to the center of the end wall 18 of the cylinder 12 and guided and supported in the hole 4 of the partition wall 8. This hole 4 communicates with an outlet 7 via an exhalation port 6. However, such a configuration is not necessarily required.

Next, the operation of the vacuum pump according to the present invention will be explained. When the cylinder 12 is pushed up by the cam 16 as the camshaft 23 rotates, the air in the pump chamber 14 pushes open the check valve 5 through the passage 17 and is discharged to the outlet 7. When the cam 16 further rotates, the cylinder 12 is pushed down by the force of the spring 20 and the volume of the pump chamber 14 increases, so that air from a negative pressure tank (not shown) flows from the inlet 10 to the passage 3.
Then, the check valve 15 is pushed open and the liquid is sucked into the pump chamber 14. Due to such reciprocating motion of the cylinder 12, the air in the negative pressure tank is intermittently discharged to the outside.
A negative pressure source is created in the negative pressure tank.

[Effects of the invention] As mentioned above, the present invention constitutes a pump chamber by fitting a cup-shaped cylinder to an immovable piston equipped with a pair of check valves on the end walls that allow flow in opposite directions. , the end wall of the cylinder is biased and engaged with the cam of the camshaft by a spring, and the cup-shaped cylinder is configured to be directly reciprocated by the cam of the camshaft, so it is different from the conventional one. Unlike the previous example, there is no need for a piston rod, and the overall shape of the pump is extremely flat, resulting in a significant reduction in installation space. Furthermore, since the pair of check valves are directly attached to the end wall of the piston, the configuration is simplified and the number of parts is reduced, which is advantageous in reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view showing an embodiment of a vacuum pump according to the present invention installed in a cylinder head. 2... Piston, 5, 15... Check valve, 7...
Outlet, 8... Bulkhead, 9... Mounting wall, 10... Inlet, 12... Cylinder, 14... Pump chamber, 16
...Cam, 20...spring.

Claims (1)

[Scope of utility model registration request] The pump chamber is constructed by fitting a cup-shaped cylinder to an immovable piston whose end walls are equipped with a pair of check valves that allow flow in opposite directions.The end wall of the cylinder is connected to the cam of the camshaft by a spring. A vacuum pump characterized by biased engagement.